tag:theconversation.com,2011:/au/topics/animal-diet-7859/articlesAnimal diet – The Conversation2023-10-15T04:44:57Ztag:theconversation.com,2011:article/2128842023-10-15T04:44:57Z2023-10-15T04:44:57ZElephant teeth: how they evolved to cope with climate change-driven dietary shifts<figure><img src="https://images.theconversation.com/files/553246/original/file-20231011-15-nnhghm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Proboscideans and their tooth structures in various forms across 60 million years of evolution.</span> <span class="attribution"><span class="source">Illustration by Óscar Sanisidro. Author provided (no reuse) </span></span></figcaption></figure><p>Seeing elephants in the wild is a timelessly awe-inspiring experience. There are only three living species today: the African savannah elephant, African forest elephant, and Asian elephant. </p>
<p>They are the remnants of a once prosperous lineage of megaherbivores called proboscideans, whose evolutionary epic <a href="https://www.nature.com/articles/s41559-021-01498-w">spanned 60 million years and some 200 species</a>. The African continent was the centre stage of this story.</p>
<p>But, until now, it hasn’t been clear how natural selection favoured modern elephants as the only tiny surviving branch of proboscideans.</p>
<p>A <a href="https://www.nature.com/articles/s41559-023-02151-4">new study</a> by palaeontologists Juha Saarinen and Adrian Lister provides the answers. Lister supervised my PhD, which focused on evolutionary relationships of fossil elephants. Saarinen hosts my current postdoctoral position at the University of Helsinki, as we’re pursuing research stemming from these findings.</p>
<p>They focused on the emergence of elephants’ highly specialised, multi-plated cheek teeth from the primitive dentition of earlier proboscideans. Their conclusions demonstrate that behavioural adjustments in response to changing environments can produce sustained transformative trends in animals’ adaptive structures over tens of millions of years.</p>
<h2>Teething problems</h2>
<p>Modern elephants’ diets consist of copious amounts of tough, fibrous, often low-quality fodder. They’re able to eat this way because of their teeth: six massive grinding teeth per jaw half that erupt and expend sequentially in a <a href="https://www.tandfonline.com/doi/full/10.1080/08912963.2017.1297436">horizontal “queue”</a> throughout the animal’s life, each successively larger than the previous tooth. The adult molars are as big as bricks.</p>
<p>Enamel ridges that align longitudinally along the tooth shear up the vegetation like a cheese grater as the <a href="https://www.jstor.org/stable/2407059">jaws move</a>. These teeth also have high crowns that continuously erupt into position as the older chewing surface wears away, like lead pushing up in a mechanical pencil. This helps elephants deal with continuous tooth attrition from chewing.</p>
<p>The fossil record shows that, 20 million years ago, proboscidean teeth looked completely different. These teeth had rounded cusps aligned in pairs, versatile for chewing up a wide range of plant food in the primeval forests and thickets they inhabited. But they were ill-suited for tackling large quantities of tough, abrasive vegetation.</p>
<p>Scientists theorised that two major factors drove the evolution of wear-resistant dental features seen in elephants today. One was the spread of grass that could tolerate a cooler, drier and more seasonal climate than the cosy forest homes ancestral proboscideans occupied. The second was that large herbivores ingested more adhesive dust in these new arid environments than they had before. </p>
<p>Both challenges arose within the past 20 million years. But it wasn’t clear exactly how these two factors drove adaptive changes in herbivore teeth. The theory also presented a chicken-and-egg paradox: which took off first, the evolving teeth or the altered habitats?</p>
<h2>The evidence</h2>
<p>Saarinen devised a simple quantitative method to solve this conundrum. It’s founded on a basic mechanical principle. The way grazers eat wears the teeth flat, while browsers’ teeth have a more “edged” chewing surface. That means grazing elephants should develop angles of wear on their teeth that are wider than those of browsing elephants.</p>
<p>To test this idea, Saarinen first measured recent elephant teeth from Kenya’s Tsavo East National Park, which <a href="https://www.tandfonline.com/doi/full/10.1080/02724634.2014.918546?casa_token=GffcFE5RAO4AAAAA">confirmed his initial postulation</a>. He and Lister then turned to Africa’s wealth of geological and fossil records.</p>
<p>Their tooth wear measurements from fossils revealed that, about 21 million years ago, the first increase in dietary uptake of grass was achieved by the primitive “<a href="https://www.britannica.com/animal/gomphothere">gomphothere</a>”-type proboscideans of Africa. Gomphotheres were the generalised ancestral stock from which modern elephants and their other extinct relatives evolved.</p>
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<a href="https://theconversation.com/from-enormous-elephants-to-tiny-shrews-how-mammals-shape-and-are-shaped-by-africas-landscapes-203689">From enormous elephants to tiny shrews: how mammals shape and are shaped by Africa's landscapes</a>
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<p>They also discovered that these gomphotheres grazed more as grass cover expanded across their habitats between 21 million and 6 million years ago, as indicated by plant fossil fragments from the sites where the gomphothere teeth were found. Yet this was achieved with little structural evolution in their teeth. </p>
<p>This was a boom period for African proboscidean diversity. Habitats containing three or four proboscidean species were common. Some species adopted grazing to minimise competition with neighbouring pachyderms that preferred softer fodder.</p>
<h2>Ultimate survivors</h2>
<p>To scrutinise previously theorised links between climate, vegetation change and elephant evolution, Saarinen and Lister examined records from sediment cores drilled off Africa’s west and east coasts over previous decades. Those cores are essentially archives, capturing tens of millions of years of environmental changes on the continent. Arid periods are marked by dustier segments of the core.</p>
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Read more:
<a href="https://theconversation.com/fossil-tracks-and-trunk-marks-reveal-signs-of-ancient-elephants-on-south-africas-coast-164306">Fossil tracks and trunk marks reveal signs of ancient elephants on South Africa's coast</a>
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<p>Statistical testing of the data showed that the African environment began to get drastically more arid between 7 million and 5 million years ago, and this drove a vast increase in the rate of dental evolution in the lineage that gave rise to mammoths and modern elephants, as well as promoting the further spread of grasslands. </p>
<p>Thus came proof that the high-crowned, multi-plated molars of elephants evolved primarily to withstand grit, rather than fibre, in their food. This new dental form provided such an advantage that, <a href="https://link.springer.com/article/10.1007/s10914-011-9181-y">around 3.6 million years ago</a>, early elephants had outcompeted the last African gomphotheres into extinction.</p>
<h2>New research avenues</h2>
<p>The zenith of this evolutionary ratchet was <a href="https://www.nhm.ac.uk/discover/news/2020/february/weird-skulls-of-straight-tusked-elephants-reveal-how-many-species.html"><em>Palaeoloxodon</em></a>. It was the <a href="https://www.app.pan.pl/archive/published/app61/app001362014.pdf">largest elephant to evolve</a>, standing over 4 metres tall at the shoulder and weighing 12–15 tonnes. With brick-sized molars packing up to 21 grating plates, <em>Palaeoloxodon</em> was the undisputed top megaherbivore of the African savannah between 1.5 million and around 130,000 years ago, in both its stature and feeding adaptations. </p>
<p>Yet, within the last million years of our story, when African savannahs became <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1909284116">increasingly arid and seasonal</a> just as they did for the previous 5 million years, these spectacular grazing specialists vanished. Why?</p>
<p>Upon discussing his findings, Saarinen and I converged on a hypothesis. Modern African elephants are half the size of their prehistoric cousins, with teeth less specialised towards a grass-dominated diet. This may be key for elephants to tolerate the arid shrublands of today’s Africa, which have little grass cover to support such enormous grass-dependent vegetarians as <em>Palaeoloxodon</em>. </p>
<p>We’re examining this as part of our current research, hoping to decipher whether the encroachment of grasslands by shrubby arid zones drove the extinction of <em>Palaeoloxodon</em> and other spectacular giant herbivores in Africa over the past million years. The story we ultimately tell may serve as a stark warning for how climate change will further decimate African biodiversity, if it’s left unchecked.</p><img src="https://counter.theconversation.com/content/212884/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steven Zhang conducts research at the University of Helsinki, hosted through funding from the Research Council of Finland awarded to Juha Saarinen. </span></em></p>Groundbreaking study demonstrates how behaviour drives long-term evolution over 20 million years.Steven Zhang, Postdoctoral Researcher, University of HelsinkiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1851182022-07-20T18:33:22Z2022-07-20T18:33:22ZMegalodon sharks ruled the oceans millions of years ago – new analyses of giant fossilized teeth are helping scientists unravel the mystery of their extinction<figure><img src="https://images.theconversation.com/files/474715/original/file-20220718-72671-te0fb6.png?ixlib=rb-1.1.0&rect=133%2C118%2C2944%2C2035&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Megalodon would have dwarfed today's great white sharks.</span> <span class="attribution"><span class="source">Christina Spence Morgan</span></span></figcaption></figure><p>Millions of years ago, giant sharks three times larger than today’s great whites stalked the world’s ocean. They’re long gone now, but occasionally, someone walking on a beach <a href="https://www.bbc.co.uk/news/uk-england-suffolk-61378018">spots an odd triangular shape in the sand</a>. On closer inspection, they realize it’s a fossilized tooth as large as a human hand, with sharp serrated edges. And they have to wonder: What was that beast eating?</p>
<p>These fossilized teeth hold clues to a mystery about a legend of the seas, a mammoth creature that was at the apex of the food chain – and then vanished. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An adult hand holds a giant shark tooth that covers it from the palm to the fingertips." src="https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=737&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=737&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=737&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=926&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=926&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474347/original/file-20220715-12-dfgdi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=926&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A megalodon tooth found on the North Carolina coast.</span>
<span class="attribution"><span class="source">Harry Maisch</span></span>
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<p>It’s known as the megalodon, believed to be the largest shark species to ever exist. Evidence in the teeth and bite marks found on fossilized bones suggest these ancient sharks were swimming the ocean between 23 million and <a href="https://doi.org/10.7717/peerj.6088">3.5 million years ago</a>. Scientists have estimated they reached <a href="https://www.theguardian.com/environment/2020/sep/03/researchers-reveal-true-scale-of-megalodon-shark-for-first-time">lengths upwards of 50 feet (15 meters)</a> – longer than a city bus.</p>
<p>The megalodon was the last species of a group of sharks called the megatooth sharks. We study the chemistry of fossils to better understand ancient animals, and while many mysteries remain about megalodon’s life and eventual extinction, its teeth are revealing some answers.</p>
<h2>What did ancient sharks eat?</h2>
<p>There are tantalizing clues about the diet of ancient sharks in the fossil record. </p>
<p>The shape and structure of their teeth can indicate general eating styles. Broad serrated megalodon teeth are thought to be particularly well adapted to gnawing on marine mammals, while the sharp and pointy teeth of other sharks lend themselves to piercing and tearing fish.</p>
<p>In some exceptional cases, fossil marine mammal bones have been found with the <a href="https://chesapeakebaymagazine.com/megalodon-bite-marks-found-on-calvert-cliffs-fossil/">bite</a> <a href="https://doi.org/10.1016/j.palaeo.2017.01.001">marks</a> <a href="https://www.popsci.com/science/megalodon-diet-sperm-whale-head/">of a megalodon</a>. Some <a href="https://doi.org/10.1098/rspb.2022.0774">sperm whale bones</a> have evidence of megalodon attacks on their foreheads, a part of the whale that would have been rich in fats. <a href="https://chesapeakebaymagazine.com/megalodon-bite-marks-found-on-calvert-cliffs-fossil/">Dolphin tailbones</a> have also been found with deep megalodon tooth marks. Each of these incredible fossils offers a snapshot of one megalodon’s meal on one day millions of years ago. </p>
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<img alt="Large bite marks on part of a whale backbone." src="https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=461&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=461&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=461&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=579&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=579&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474352/original/file-20220715-20-zth067.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=579&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">This whale vertebra was bitten in half by a megalodon.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Meg_bitten_cetacean_vertebra.jpg">Jayson Kowinsky via Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Were marine mammals a part of megalodon’s regular diet, or just a special snack that day? And what else may have fallen prey to this massive shark?</p>
<h2>Finding answers in the chemistry of fossil teeth</h2>
<p>Using newly developed tools, we have been able to analyze the chemical composition of these fossil teeth, including samples from the United States, western Europe and Japan. </p>
<p>The results, published in two recent studies, tell us about the diet of each ancient shark and about the environment it lived in long before humans walked the Earth.</p>
<p>When animals eat, they acquire <a href="https://organismalbio.biosci.gatech.edu/nutrition-transport-and-homeostasis/nutrition-needs-and-adaptations/">nutrients</a> from their meals, including nitrogen and zinc. Because of this, nitrogen and zinc are passed up the food web from prey to predator.</p>
<p>Both nitrogen and zinc have multiple stable <a href="https://theconversation.com/explainer-what-is-an-isotope-10688">isotopes</a>, forms whose atoms contain the same number of protons but different numbers of neutrons. For nitrogen, the ratio of the 15-nitrogen isotope to the 14-nitrogen isotope <a href="https://thefisheriesblog.com/2017/06/04/determining-trophic-position-everyone-gets-a-trophy-but-only-the-top-doesnt-get-eaten/">increases with each step up the food web</a> because animals tend to discard more of the 14-nitrogen isotope in their waste. On the other hand, the ratio of 66-zinc to 64-zinc decreases within animals higher up in the food web.</p>
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<a href="https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration shows different sharks by period when they lived. Maglodon is the largest and an apex predator" src="https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474661/original/file-20220718-69569-2vdqzi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">When megalodon and its megatooth ancestors lived, and their position in the food web as apex predators compared with sharks that primarily eat fish.</span>
<span class="attribution"><span class="source">Christina Spence Morgan</span></span>
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</figure>
<p>Very small amounts of nitrogen and zinc are preserved deep inside the mineral layers of fossil teeth. We can extract and purify these elements from the teeth, measure the isotope ratios, and then estimate the position in the food web, for each ancient shark. </p>
<p>While nitrogen isotopes are often measured in modern protein tissues, these decompose rapidly and cannot be measured in the fossil record. This new method of measuring nitrogen isotopes can analyze the trace amount of nitrogen preserved in the mineral layers of fossil teeth over millions of years. The zinc isotope method is also new; this study marks the first time it has been applied to sharks and fossils more than 86,000 years old.</p>
<p>Together, the isotopes of nitrogen and zinc in fossil teeth tell us about the diet of extinct animals living in ecosystems that vanished millions of years ago. In our studies, we used <a href="https://doi.org/10.1126/sciadv.abl6529">nitrogen</a> and <a href="https://doi.org/10.1038/s41467-022-30528-9%22%22">zinc</a> isotopes to reconstruct the diets of sharks. </p>
<h2>Megalodon’s extinction: Competition with the white shark?</h2>
<p>Understanding the diet of the megalodon can help us unravel the mystery of its extinction, and the possible ripple effects of its disappearance on marine ecology.</p>
<p>Both measurements show that the megalodon – and its slightly smaller megatooth ancestors – were feeding at an extraordinarily high position in ancient food webs. In fact, at least according to the nitrogen isotopes, they may have been higher than any apex predator existing today.</p>
<p>To be in such a high position they may have been eating now-extinct marine mammals, such as predatory sperm whales. Megalodon might also have been cannibalistic, maybe with larger adults eating juveniles. It’s very likely that the megalodon was a true apex predator, not targeted as prey by any other marine animal. </p>
<figure class="align-center ">
<img alt="A pile of very large shark teeth" src="https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474351/original/file-20220715-12-eypa2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Megalodon was here. Several of the shark’s giant teeth have been found along the North Carolina coast.</span>
<span class="attribution"><span class="source">Harry Maisch</span></span>
</figcaption>
</figure>
<p>The emergence of the modern white shark around 5 million years ago has been hypothesized as one factor that could have contributed to megalodon’s extinction. </p>
<p>White sharks were believed to have fed on similar prey. There are similarities in tooth shape, and <a href="https://doi.org/10.1038/s41467-022-30528-9">fossil bite marks on similar species</a> also suggest that the white sharks <a href="https://www.abc.net.au/news/science/2022-06-01/megalodon-extinction-great-white-shark-pliocene-diet-zinc/101112348">may have outcompeted</a> megalodon, or <a href="https://doi.org/10.1126/sciadv.abl6529">outcompeted juvenile megalodon</a>.</p>
<p>The isotopes offer conflicting answers. The comparison of nitrogen isotopes between great whites and megalodon from around the same time period placed these predators at different positions in the food web, meaning that they were not competing for the same prey. The zinc isotopes, however, <a href="https://www.abc.net.au/news/science/2022-06-01/megalodon-extinction-great-white-shark-pliocene-diet-zinc/101112348">do not reject the competition hypothesis</a>, placing these two sharks at similar positions in the food web instead. </p>
<p>The disappearance of the giant sharks could have been caused by other factors, too, such as temperature changes, the loss of shelf environments due to sea-level fall, or, likely, a combination of influences.</p>
<p>Future research combining both methods may help resolve this conundrum and finally solve the mystery of why the largest shark on Earth vanished.</p>
<p><em>Michael Griffiths of William Paterson University and Kenshu Shimada of DePaul University contributed to this article.</em></p><img src="https://counter.theconversation.com/content/185118/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sora Kim receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Emma Kast and Jeremy McCormack do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Megalodon, the world’s largest known shark species, swam the oceans long before humans existed. Its teeth are all that’s left, and they tell a story of an apex predator that vanished.Emma Kast, Postdoctoral Research Fellow in Geosciences, University of CambridgeJeremy McCormack, Specialist in Geoscience, Goethe University Frankfurt am MainSora Kim, Assistant Professor of Paleoecology, University of California, MercedLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1034922018-09-26T11:23:57Z2018-09-26T11:23:57ZOmnivore sharks and cannibal hippos – the strange truth about dinnertime in the animal kingdom<figure><img src="https://images.theconversation.com/files/238101/original/file-20180926-48662-1ihwgwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hippo-mouth-open-kruger-national-park-510400405?src=WchcNLAlxVcBVCBdBtDENg-1-1">Katy Foster/Shutterstock</a></span></figcaption></figure><p>Animals don’t always stick to traditional menus, and they certainly don’t read the descriptions of their diets we include in textbooks. When it recently emerged that a notorious carnivore (a shark) was <a href="http://www.theguardian.com/environment/2018/sep/05/bonnethead-omnivorous-shark-species-identified">actually selecting the vegetarian option</a>, scientists were intrigued. </p>
<p>We’ve known for some time that bonnethead sharks consume large quantities of seagrass, but this was <a href="http://rspb.royalsocietypublishing.org/content/285/1886/20181583?utm_source=yxnews&utm_medium=mobile">thought to be accidental</a> – pesky vegetation finding its way into their mouths while they were hunting crabs. Yet this new research has revealed that the bonnethead shark actually digests and draws nutrition from the seagrass – the first known omnivorous shark.</p>
<p>This finding isn’t just an interesting new fact about sharks, it’s an important acknowledgement that environments need to be protected for reasons we may not have even considered. Who’s to say there aren’t other examples of species interacting with their habitats in unexpected ways? </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/238097/original/file-20180926-48665-13kckft.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A bonnethead shark contemplating its next meal.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Bonnethead_new_orleans.jpg">Mills Baker/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<p>The natural world is far from fully understood, and while new scientific discoveries continue to be made, these revelations aren’t keeping pace with the <a href="https://ourworld.unu.edu/en/rate-of-environmental-degradation-puts-life-on-earth-at-risk-say-scientists">rate of environmental destruction</a>. Equally, nature seems to have a habit of surprising us. Or perhaps it’s just that we forget that animals don’t read the books we write about them.</p>
<p>In the field of feeding ecology alone, there are multiple examples of animals breaking the “rules” we’ve set for them. If the plant-eating shark was a shock, what about supposedly strict vegetarians turning to meat? Although <a href="https://link.springer.com/article/10.1007/s10344-015-0980-y">carcass-eating bunnies</a> and <a href="https://news.nationalgeographic.com/news/2015/01/150123-hippos-cannibalism-animals-food-science/">cannibal hippopotamuses</a> may sound like something out of a horror movie, they aren’t restricted to the imaginations of screenwriters. </p>
<h2>The food chain’s grislier links</h2>
<p>Let’s take the case of the hippo first. These iconic African animals are described in most textbooks as strict herbivores, who only use their large tusks and teeth for <a href="https://www.livescience.com/27339-hippos.html">display and territorial fights</a>. However, the rotund vegetarians have been seen consuming animal carcasses, <a href="https://news.nationalgeographic.com/news/2015/01/150123-hippos-cannibalism-animals-food-science/">including other hippos</a>. This behaviour is not isolated to a single observation and scientists believe it may even help diseases such as <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/mam.12056">anthrax to spread more widely</a> throughout hippo populations.</p>
<p>As for the cute and fluffy bunnies, even these will choose meat over veg in some circumstances. In a mixed-species zoo exhibit, the chicken and mice offered to captive birds of prey were <a href="https://link.springer.com/article/10.1007/s10344-015-0980-y">actually consumed by domestic rabbits</a> sharing the enclosure.</p>
<p>More gruesome examples of erstwhile vegetarians abound. The poor table manners of sheep and deer were reported in the late 1980s, as they were seen biting the legs, wings and heads off <a href="https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1988.tb02451.x">fledgling chicks</a>. Only a few months ago, startling footage of rare <a href="https://twitter.com/nat_b_zielonka/status/1001555173859381248?lang=en">curlew nests</a> being raided by sheep in the UK caused a sensation on social media.</p>
<p>But the dining tables are turned in New Zealand, where it’s sheep who are the victims. The kea bird, New Zealand’s friendly “mountain clown”, is a native parrot with a taste for open wounds on livestock, and can often be seen plucking tissue and blood from the animals while perched on their backs. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/237928/original/file-20180925-149958-fw02du.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Don’t be fooled.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/keas-alpine-parrots-sitting-together-arthurs-163096301?src=x6q_ASLTTMfuVnWpdk7tRw-1-7">Shaun Jeffers/Shutterstock</a></span>
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<p>As early as 1895, the <a href="https://www.nature.com/articles/052629b0.pdf">species’ feeding habits</a> were the subject of scientific interest. However, it was the interest of farmers in these birds that warranted the greatest concern, as the keas’ apparent thirst for blood prompted <a href="https://www.nzgeo.com/stories/kea-the-feisty-parrot/">a campaign to exterminate them</a>.</p>
<p>The jury may still be out as to whether keas are clowns or killers, but what does appear accurate is that they are highly <a href="https://www.nzgeo.com/stories/kea-the-feisty-parrot/">adaptable opportunists</a> who don’t play by any rules we may make for them.</p>
<h2>A fresh look at food choices</h2>
<p>These examples <a href="https://link.springer.com/article/10.1007/s10344-015-0980-y">force us to rethink</a> the notion that feeding habits are a simple reflection of gut anatomy. Perhaps feeding behaviour and strategies are driven more by opportunity than <a href="https://link.springer.com/article/10.1007/s10344-015-0980-y">physiology</a>.</p>
<p>Rabbits, hippos and keas don’t have anatomies which make them good at capturing prey, but that doesn’t mean to say they can’t, and won’t, make use of animal tissues if they get the chance. Likewise, not all carnivores may be as hungry for meat as we once thought. </p>
<p>Free-living animals must make the most of the opportunities presented in their environment. If that means tucking into a chum that’s just died, or taking a <a href="https://theflexitarian.co.uk/flexitarian-diet-2/">flexitarian</a> approach to one’s dietary regime, then that’s what they’ll do. </p>
<p>After all, as my colleague <a href="https://www.researchgate.net/profile/Ellen_Dierenfeld">Ellen Dierenfeld</a> pointed out, carnivores and herbivores are just two extreme ends of the scale, and it’s only humans that tend to think of the points on that scale as immovable. So until the animals learn to write their own textbooks, we should be prepared for the unexpected, and never take anything off the menu when it comes to understanding the natural world.</p><img src="https://counter.theconversation.com/content/103492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katherine Whitehouse-Tedd does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sharks eating seagrass? Sounds fishy, but the reality is that animals don’t conform to the strict categories we try to place on their diets.Katherine Whitehouse-Tedd, Senior Lecturer, School of Animal, Rural and Environmental Sciences, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/962722018-05-13T20:30:20Z2018-05-13T20:30:20ZIs that selfie really worth it? Why face time with wild animals is a bad idea<figure><img src="https://images.theconversation.com/files/218555/original/file-20180511-4803-1ryd77f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Kangaroos probably don't enjoy social media photos as much as we do.</span> <span class="attribution"><span class="source">Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The phenomenon of kangaroo selfies hit the headlines earlier this month, when several tourists were injured while feeding wild kangaroos in Lake Macquarie, north of Sydney. They may have wanted a memorable holiday snap, but ended up with rather more than they bargained for.</p>
<p>One <a href="http://www.abc.net.au/news/2018-05-02/agro-kangaroos-addicted-to-carrots-attack-tourists/9716612">news report</a> described how the “cute and cuddly” animals had begun “viciously attacking people”. </p>
<p>Is that really fair on the kangaroos? Of all the adjectives you could use to describe an animal that is territorial, fiercely maternal and has large claws, “cuddly” is pretty far down the list.</p>
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Read more:
<a href="https://theconversation.com/tinders-tiger-selfies-show-the-perils-of-wildlife-close-encounters-30083">Tinder's tiger selfies show the perils of wildlife close encounters</a>
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<p>The problem with that description of the incident is that it suggests that the kangaroos were to blame for the injuries. In reality, it was the fault of the people getting too close and offering them the wrong food. Having become so used to being handed carrots, we can hardly blame the kangaroos for being “hopped up”, as the news coverage punningly put it.</p>
<p>In India, another recent case ended in tragedy when a man attempted to take a selfie with a <a href="http://www.fox13news.com/news/man-tries-to-take-selfie-with-bear-bear-kills-him">bear</a>. The man reportedly turned his back on the bear and was then mauled to death.</p>
<h2>Selfie society</h2>
<p>The growing danger of animal selfies, and of feeding wild animals, is well documented. People have been killed and injured by tigers, such as in the case of a <a href="http://www.dailymail.co.uk/news/article-503529/Tigers-maul-tourist-death-tries-photo-zoo-cage-bars.html">zoo visitor in India who climbed over a safety barrier</a> in search of a better photo. Wild long-tailed macaques at Bali’s Uluwatu Temple have got so used to being fed that they <a href="https://www.newscientist.com/article/2132748-monkey-mafia-steal-your-stuff-then-sell-it-back-for-a-cracker/">steal tourists’ valuables</a> and only drop them when given snacks.</p>
<p>A 2016 <a href="https://academic.oup.com/jtm/article/23/2/tav026/2580644">study</a> in the Journal of Travel Medicine recommended that: </p>
<blockquote>
<p>…scenarios where selfies should be avoided include photographs taken from a height, on a bridge, in the vicinity of vehicular traffic, during thunderstorms, at sporting events, and where wild animals are in the background.</p>
</blockquote>
<p>Interacting with wild animals isn’t just dangerous for people. It can be bad news for the animals too. A 2017 <a href="https://link.springer.com/chapter/10.1007/978-3-319-55574-4_14">study</a> looked specifically at kangaroos who are exposed to wildlife tours. It concluded that both wild and captive kangaroos can be stressed by humans approaching them closely, and that the presence of tourists may drive them away from feeding, breeding or resting areas. It also noted that the potential knock-on effects for kangaroo population numbers are still unknown. </p>
<p>A <a href="https://www.sciencedirect.com/science/article/pii/S0261517701000802">review in the journal Tourism Management</a>, written after a nine-year-old boy was <a href="https://www.theguardian.com/world/2001/may/01/patrickbarkham">killed by dingoes on Queensland’s Fraser Island in 2001</a>, confirmed that routinely feeding wild animals can alter their behaviour patterns and population levels. There was no suggestion that the boy was engaging in risky behaviour, but rather that the dingoes had become dangerously habituated to human presence, as a result of previous feeding by tourists and easy access to campsite food. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=556&fit=crop&dpr=1 754w, https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=556&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/218557/original/file-20180511-34024-d0udq3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=556&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Advice to stay a safe distance from wild animals is all too often ignored.</span>
<span class="attribution"><span class="source">Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>You might shake your head in disbelief at the idea of turning your back on a wild bear in search of the perfect selfie. But how many of you have taken a photo with an animal and posted it on social media? </p>
<p>These photographs, even if they are of habituated animals in urban areas or in a zoo, can endanger wild animals and cause them undue stress (as discussed in a previous <a href="https://theconversation.com/even-scientists-take-selfies-with-wild-animals-heres-why-they-shouldnt-61252">article</a>). Taking a selfie of a zoo animal can leave the impression that kangaroos, koalas and other “fluffy” animals act like this in the wild. People who don’t know about the normal behaviour of these animals may therefore think that these animals are OK to approach in the wild. This could explain why so many tourists still consider it safe to approach wild kangaroos.</p>
<p>While some wild animals are undoubtedly cute, we should be sensible enough not to expect them to be cuddly. We need to respect wild animals’ behaviour and territories, so as to avoid injury and live in harmony.</p>
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<strong>
Read more:
<a href="https://theconversation.com/even-scientists-take-selfies-with-wild-animals-heres-why-they-shouldnt-61252">Even scientists take selfies with wild animals. Here's why they shouldn't.</a>
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<p>Zoos in Australia generally house hand-reared animals, many of which are used to being fed and petted by people in a safe and monitored environment. The animals are given carefully selected diets, as well as places to which they can retreat if they have had enough interaction. All of this helps to minimise the stress on the animals and the risk to people. And of course, there is the broader point that zoo animals deserve respect and are not just cuddly toys.</p>
<p>Just because you can pat and feed a kangaroo at a zoo, does not mean you can do it elsewhere. Zoos can play their part by promoting advice about safe behaviour around wild animals elsewhere. </p>
<p>So next time you’re lucky enough to see kangaroos or another animal in the wild, by all means take a photo - if you can do it from a safe distance. And ask yourself whether you really need to be in it too.</p><img src="https://counter.theconversation.com/content/96272/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kathryn Teare Ada Lambert does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Here’s some advice on taking selfies with wild animals: don’t. It’s not fun for the animal, and can have serious knock-on effects for their health. And you could be injured (or worse).Kathryn Teare Ada Lambert, Adjunct Lecturer/ Ecologist, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/651712016-11-20T12:10:53Z2016-11-20T12:10:53ZFeeding pigs in Africa is expensive. Changing their diets is the answer<figure><img src="https://images.theconversation.com/files/146054/original/image-20161115-31132-zhdeme.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">One of the major reasons for the lack of growth in pig production is high pig feed costs.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Pork is one of the cheaper protein sources that can contribute towards food security in Africa. Pigs are omnivores, and as such are ideally suited to convert non human edible feed stuffs into high quality food animal protein. Pork consumption has grown tremendously over the years across the world, but production has not responded sufficiently to meet demand. It has been projected that almost 45% of additional pork consumption will <a href="http://www.oecd-ilibrary.org/docserver/download/5116021e.pdf?expires=1479236491&id=id&accname=guest&checksum=8F7EB07EB62E3D55E5C66071F3B484C3">be imported</a>.</p>
<p>Pig numbers in Africa increased steadily from 33.8 million in 2013 to 34.5 million <a href="http://faostat3.fao.org/browse/Q/QA/E">in 2014</a>. But this rate will clearly not be sufficient to meet the demands of a growing population on the continent which currently stands at about 950 million people. Between 2013 and 2015 pork made up 12% of all meat consumed in sub Saharan Africa. This is <a href="http://www.keepeek.com/Digital-Asset-Management/oecd/agriculture-and-food/oecd-fao-agricultural-outlook-2016-2025/livestock-mix-across-the-sub-saharan-african-region_agr_outlook-2016-graph23-en#.WCr26tJ97IU#page1">much lower</a> than poultry (36%), beef (33%) and sheep (19%). Cultural and religious concerns have largely limited pork consumption in many countries but urbanisation is changing this. </p>
<p>One of the major reasons for the lack of growth in pig production is high pig feed costs. Pig producers normally use a narrow range of ingredients which include maize, wheat, sorghum, soybean oilcake and sunflower oilcake among others in formulating pig diets. They are often forced to compete with humans and poultry for feed resources, making the cost of producing pigs prohibitive. Recurring droughts due to global warming are exacerbating the situation. </p>
<p>The other problem is that some high fibre diets aren’t the best for pig production. Pigs don’t grow as fast because some fibre – like wheat bran – reduces feed intake and dilutes the available protein, energy, minerals and vitamins necessary for growth. But not all fibres are the same: some are better than others.</p>
<p>To solve both the cost and the fibre issues the pig industry must find ways to effectively make use of readily available fibrous feeds from industries that <a href="https://www.cambridge.org/core/journals/animal/article/influence-of-dietary-fibre-level-and-pelleting-on-the-digestibility-of-energy-and-nutrients-in-growing-pigs-and-adult-sows/2CABC3780687019F6D4B5AD97D6099AF">process agricultural products</a>. This would result in cheaper production of pigs and a more food secure continent.</p>
<h2>What fibres work and which ones don’t</h2>
<p>The major challenge in using fibrous feeds in pig diets is that pigs’ digestive enzymes can’t break down certain fibre components to a state that can be utilised by the animals. In addition, high fibre diets increase the rate of feed passage in the pig gut and trap nutrients in the fibre matrix making them unavailable <a href="http://www.thepigsite.com/articles/4910/high-fibre-swine-diets/">for digestion</a>. Fibre also imputes bulkiness to diets which limits the quantity of feed the pig can consume. </p>
<p>But fibres shouldn’t be grouped under a blanket term. Not all are a bad food choice for pigs. Fibres differ in their physical and chemical properties which affects the solubility of the fibre. Soluble and insoluble components of fibre differ in how they influence the number, range and types of microorganisms in the gut, fermentation patterns and absorption of nutrients.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/146206/original/image-20161116-13503-opyg4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pork has the
ability to help Africa’s food security.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>A better understanding of these dynamics will lead to sustainable use of fibrous ingredients in pig diets. Sugar beet pulp, for example, is highly soluble and can be used at relatively high levels. Meanwhile wheat bran, which is highly insoluble, may be used in moderate quantities because of its laxative effects.</p>
<p>Pigs can also extract up to 25% of the energy they need from fibre fermentation products. This would mean that grains in their <a href="http://ajas.info/journal/view.php?doi=10.5713/ajas.15.0053">diets</a> could be reduced. Besides the economic benefits from using cheaper fibrous byproducts in pig feed, there are also environmental gains. Most of these byproducts are often dumped inappropriately leading to water and air pollution.</p>
<h2>The impact of fibrous diets</h2>
<p><a href="https://jasbsci.biomedcentral.com/articles/10.1186/2049-1891-4-11">Most research</a> has focused on the impact of the fibrous diets on growth performance of the pigs. But there is a need to quantify the beneficial effects of high fibre diets on intestinal health and welfare.</p>
<p>Dietary fibre improves pig health by promoting the growth of lactic acid bacteria, the “good bacteria”. These suppress the multiplication of disease causing bacteria like <em>E. coli</em> and <em>Salmonella</em> by lowering the pH in the <a href="https://www.ncbi.nlm.nih.gov/pubmed/26500769">pig intestines</a>. This contributes to food safety because people can get <em>E. coli</em> and <em>Salmonella</em> from eating pig meat that’s been contaminated in this way, poisoning them.</p>
<p>Dietary fibre also reduces stress and behavioural <a href="http://www.appliedanimalbehaviour.com/article/S0168-1591(03)00305-8/references">problems in pigs</a>. This is especially important given that intensive farming is increasingly being used to produce pigs. This has been shown to be quite stressful with detrimental effects on production. For example, <a href="https://jasbsci.biomedcentral.com/articles/10.1186/2049-1891-4-11">sows appear to be less stressed</a> and to move around less if they are physically and nutritionally satisfied.</p>
<p>Pigs can also use diets with high fibre better if enzymes that break down fibre are added to their diets. Another option is to allow the fibrous sources of pig feed to ferment under anaerobic conditions (without oxygen) – a process called ensiling. Ensiling breaks down fibre and also improves the <a href="https://www.researchgate.net/publication/270506924_Kanengoni_A_T_Chimonyo_M_Ndimba_B_K_and_Dzama_K_2015_Feed_preferencenutrient_digestibility_and_colon_volatile_fatty_acid_production_in_growing_SouthAfrican_Windsnyer-type_indigenous_pigs_and_LargeWhit">taste of the feed</a>.</p>
<p>Other approaches to break down the fibre matrix structure include fermentation and the use of fibre degrading enzymes or strong acids. These break down the fibre components to their basic constituents which is better for pigs. But the use of strong acids isn’t the best option because of safety, environmental and <a href="http://www.sciencedirect.com/science/article/pii/S036012851200007X">economic concerns</a>. </p>
<p>There are many benefits to including fibrous ingredients in pig diets, but they are not accounted for in normal diet formulations. The evidence points to the fact that high fibre diets are good for pigs and should be used more than is currently the case.</p><img src="https://counter.theconversation.com/content/65171/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arnold Kanengoni does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>High feed costs is limiting pig production in Africa. There are alternatives. The industry must find ways to use available feeds from industries that process agricultural productsArnold Kanengoni, Manager: Veterinary Services and Research, Agricultural Research CouncilLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/596832016-05-27T07:23:46Z2016-05-27T07:23:46ZThe amazing things poo can tell you about an animal’s health<figure><img src="https://images.theconversation.com/files/123539/original/image-20160523-9554-1j2nv4b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hmmm ... looks good to me.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=b3VvDBjme1134hI9waqURw-1-4&clicksrc=download_btn_inline&id=421690279&size=huge_jpg&submit_jpg=">Shutterstock</a></span></figcaption></figure><p>Caring for zoo animals requires the ability to deal with an awful lot of poo … or dung, excrement, animal waste, or faeces (the latter being used if you want to be more technical). Shovelling the proverbial is often how we start and end our day in the zoo. But aside from ensuring that we provide animals with clean environments, this process of collecting animal poo is also a vital part of their healthcare. </p>
<p>A quick Web of Science search for “faeces + zoo + animal” demonstrates just how reliant we are on poo in the zoo research and veterinary community – nearly 1,000 research articles contain a reference to faecal material from animals in zoos over <a href="https://webofknowledge.com">the past 60 years</a>. That means that the scientific community publishes an article on zoo animal poo at least once a month. </p>
<p>So, as a scientist, why am I so interested? Well, first, it’s often one of the easiest samples to get hold of from a zoo animal. You don’t need to touch the animal in order to obtain the sample, so it’s non-invasive (important from both a safety and ethical perspective). </p>
<p>Second, all animals produce it. It comes in <a href="https://theconversation.com/why-do-wombats-do-cube-shaped-poo-55975">all shapes and sizes</a> and some do it in vast quantities, such as the 100kg+ of dung produced daily by an <a href="http://www.sfzoo.org/announcements/the-scoop-on-poop-opening-day">elephant</a>. But most creatures produce manageable volumes that permit analytical techniques to be employed in a reliable manner. </p>
<p>Finally, poo offers a wide spectrum of opportunities for assessing animal health.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123944/original/image-20160525-25222-15j1vu8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Elephants are prodigious producers.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=yqSRxsF9NLuMzwxRk0xngg-1-31&clicksrc=download_btn_inline&id=388630417&size=medium_jpg&submit_jpg=">Shutterstock</a></span>
</figcaption>
</figure>
<h2>What poo tells us</h2>
<p>So what can a poo sample reveal? Let’s start with some of the more obvious aspects of poo-ology: just the presence of fresh faecal material in an animal’s enclosure assures us that the animal’s gastrointestinal tract is moving. Constipation has serious health consequences for <a href="http://www.sciencedirect.com/science/article/pii/S1521691810001599">any animal</a>, including potential toxicities, so we need to ensure that an animal is passing faeces as often as it should be. </p>
<p>But this isn’t always as simple as it sounds. Some <a href="http://eaglemountainpublishing.s3.amazonaws.com/PDF/Biology%20of%20the%20Vipers/CH%2031_lillywhite_.pdf">snakes</a> only pass faeces once every three months, while the world’s smallest bat, <a href="http://www.livescience.com/28272-bats.html">the bumblebee bat</a> has poo that is apparently as small as a pin head, making it very hard to see. So we need to establish our “species norms” before we start using poo as an indicator in any type of health check.</p>
<p>Another common use of faeces in zoos is for disease monitoring. Samples can be analysed for <a href="http://www.sciencedirect.com/science/article/pii/S0304401704004820">internal parasites</a>, such as worms and pathogens (for example bacteria or fungi) that may indicate gastrointestinal problems or even <a href="https://www.aza.org/infectious-diseases/">zoonotic diseases</a> – those that can be spread from animals to humans. </p>
<p>Many zoos will implement a routine <a href="http://www.eaza.net/assets/Uploads/Standards-and-policies/Standards-for-the-Accommodation-and-Care-of-Animals-2014.pdf">faecal screening programme</a> for their animals and this allows zoo vets to respond quickly if symptoms of disease or parasites are found, often before clinical symptoms of ill health are shown by the animal. It is also a valuable tool for monitoring the effect of any treatments, such as de-wormers. </p>
<p>Some of the research projects that I’ve been involved in recently have investigated aspects of the use of de-wormers in cheetahs and support a <a href="http://www.zoowildlifejournal.com/doi/abs/10.1638/2012-0028R1.1">diagnosis-based approach</a>. This means that, instead of routinely de-worming the animals, we should first check to see if they have any parasites present.</p>
<h2>Appearance is important</h2>
<p>But it’s not just about what’s inside the poo – you can tell a lot about an animal’s gut health just by looking at its faeces. I used a faecal consistency (shape and texture) scoring system – similar to the <a href="http://static1.1.sqspcdn.com/static/f/1451532/22180508/1363249562587/bristol_stool_chart.pdf">Bristol Stool Scale for humans</a> – to investigate how diet influences gastrointestinal disease in captive cheetahs. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123946/original/image-20160525-25218-1itsd06.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Can we get some privacy, please?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=cheetah&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=365257373">Shutterstock</a></span>
</figcaption>
</figure>
<p>My colleagues and I were able to identify some key dietary risk factors for gastrointestinal disease in cheetahs, <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0120903">just by asking the cats’ keepers about their animals’ poo</a>. For example, animals that were fed rib bones at least once a week were much less likely to have experienced diarrhoea.</p>
<p>A similar study was conducted with captive tapir and enabled the generation of feeding recommendations aimed at <a href="http://www.ncbi.nlm.nih.gov/pubmed/19681143">reducing obesity in this species</a>.</p>
<p>Colour and smell are also important. For example, the faeces of raptors (which is actually a combination of urine and faeces) will turn green when the bird has an empty gastrointestinal tract. This is important when attempting to regulate meal frequency since overfeeding can lead to infections and obesity. Green faeces in raptors can also indicate <a href="http://www.gwexotics.com/wccms-resources/1/c/6/a/30c4a98c-b62d-11e0-a685-0050568626ea.pdf">lead poisoning when combined with other symptoms</a>. </p>
<p>Understanding how zoo animals digest and utilise the diets we provide is an important step in improving zoo animal nutrition. We can measure the digestibility of key nutrients by analysing faecal samples, and we can also study aspects of the animals’ gastrointestinal function by using indigestible markers and recording the time it takes from ingestion to excretion of these markers. </p>
<p>We also use these types of markers to help us determine a poo’s owner when animals are pair or group housed. I’ve spent hours pulling zoo carnivore faeces apart looking for bits of glitter (yes, the same stuff you might find in your child’s art box), lentils, or corn kernels just to figure out whose poo is who’s. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=788&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=788&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=788&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=991&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=991&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123950/original/image-20160525-25222-1ynpzpy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=991&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Raptor: but when did it last eat?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=Jq0k5IuP-9_cOZIIeTz19g-1-28&clicksrc=download_btn_inline&id=231357505&size=medium_jpg&submit_jpg=">Shutterstock</a></span>
</figcaption>
</figure>
<p>In another study with colleagues in Belgium, faecal samples from captive cheetahs were analysed for products of hindgut fermentation (the efforts of all those microorganisms that live inside animal guts, including our own) to determine the <a href="http://www.jzar.org/jzar/article/view/81">beneficial role</a> that animal fibre, such as cartilage, bone or fur, <a href="http://www.ncbi.nlm.nih.gov/pubmed/22074361">plays in this species</a>. </p>
<p>The microbes that live inside the cheetah have also begun to be <a href="http://bmcmicrobiol.biomedcentral.com/articles/10.1186/1471-2180-14-43">characterised</a>, all thanks to that brown smelly stuff! As with the growing interest in the human microbiome, differences due to genetics, diet and the environment are also being characterised from a zoo <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2649005/">animal faecal perspective</a>. </p>
<h2>Windows into the mind</h2>
<p>Likewise, poo is important for monitoring zoo animals’ welfare as we can measure hormones called glucocorticoids and their metabolites which provide an <a href="http://www.bioone.org/doi/abs/10.1638/05-050.1">indicator of excitement and/or stress</a>. By performing long-term studies of the concentrations and patterns of these hormones in animal poo, and combining them with behavioural data, we can learn a great deal about how a zoo animal is experiencing its captive environment. </p>
<p>By monitoring the excretion of sex steroids, we can also start to understand whether females are displaying normal reproductive cycles, such as in <a href="http://www.sciencedirect.com/science/article/pii/S0378432098001122">captive rhinos</a>, or even finding out if they are pregnant, such as in <a href="http://www.sciencedirect.com/science/article/pii/S0093691X11005267">captive felids</a>. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=550&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=550&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=550&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=691&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=691&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123947/original/image-20160525-25209-1uhsceh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=691&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Rabbit: unusual appetites.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=rabbit&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=346379069">Shutterstock</a></span>
</figcaption>
</figure>
<p>Rather less savoury is coprophagia. This is the term given to the behaviour of eating faeces, either the animal’s own, or that of others. Some species have digestive adaptations that require coprophagia to be part of their normal feeding behaviour. A well-known example is the <a href="http://jn.nutrition.org/content/55/3/375.extract">domestic rabbit</a>.</p>
<p>In a zoo setting, coprophagia is also an important element of the nutritional physiology of a range of herbivores including <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2907.2002.00105.x/abstract">capybaras, some lemurs, mara, and beavers</a>. However, in some species, coprophagia is considered an abnormal behaviour which may have <a href="http://onlinelibrary.wiley.com/doi/10.1002/zoo.1430110503/abstract">nutritional origins</a> or be indicative of <a href="http://www.ncbi.nlm.nih.gov/pubmed/3492252">compromised welfare</a>. </p>
<p>Regardless of how it is used, though, those caring for animals should never underestimate the importance of a poo.</p><img src="https://counter.theconversation.com/content/59683/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katherine Whitehouse-Tedd has previously received funding from the Sea World and Busch Gardens Conservation Fund and the WALTHAM Foundation. She is affiliated with Cheetah Outreach Trust (a not-for-profit conservation organisation in South Africa). </span></em></p>No wonder scientists love it.Katherine Whitehouse-Tedd, Visiting Fellow, Animal and Equine Science, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/200612013-11-11T14:57:44Z2013-11-11T14:57:44ZAre crocodiles secret fruit-lovers?<figure><img src="https://images.theconversation.com/files/34841/original/cjnxrc7x-1384110687.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Five-a-day please.</span> <span class="attribution"><span class="source">blacktigersdream</span></span></figcaption></figure><p>Seed dispersal by animals is important for plants to help them occupy new areas of land. Usually bugs, birds, or intrepid kittens do that job. Now we can add crocodiles to that list. A new study reviewed the diets of crocodiles and showed that 13 of 18 species ate fruit of some sort and a wide variety of plants.</p>
<p>Using animals as a method of seed dispersal is actually a useful form of mutualism – the plants get to spread their genes and animals get a healthy snack. In other reptiles seed dispersal is a well-known activity, although not as well understood as for insects, mammals, birds and even in snakes.</p>
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<p>The recent study, published in the <a href="http://onlinelibrary.wiley.com/doi/10.1111/jzo.12052/abstract">Journal of Zoology</a>, shows that for crocodiles, almost a quarter of the fruits consumed were of the “fleshy” kind. However, none of the recordings were of direct observations of fruit eating, so exactly how or why they did is still a bit of a mystery.</p>
<p>Most of the evidence come from dissection of crocodiles’ stomachs and their faeces. So there is some chance that these crocodiles are indirect eaters of fruit who feast on fruit-eating animals. But direct observations (see video) have been made many times to believe that they might actually like eating fruits.</p>
<p>Why do it? First researchers that crocodiles learnt this behaviour from <a href="http://scienceblogs.com/tetrapodzoology/2008/10/03/alligators-eat-fruit/">alligators in captivity</a>. But the review makes note of observations in the wild. Perhaps it is similar to why dinosaurs consumed stones (gastroliths), to help with grinding food in their stomachs and get a tasty treat in the process. The energy values of fruits are pretty high, so consumption could be for a nutritional benefit.</p>
<p>Perhaps this odd phenomenon might help in part explain why crocodiles are such successful animals. If meat was ever in short supply, they had the capacity to diversify and track down other food sources, from vegetation and grasses.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/Urdn2m__PQI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>The study reveals something interesting about the way scientists might operate. Crocodiles are obligate carnivores – their primary diet is meat – and as such, fruits are often classed as anomalous food items when found in their stomach and not considered in a physiological context. This mainstream view may have led to the ignorance that feeding on fruits could help their diet and energy balances. </p>
<p>That the review study picked up so many independent instances of crocodiles feeding on fruit and having ingested seeds is <a href="http://phenomena.nationalgeographic.com/2013/07/26/the-puzzle-of-the-frugivorous-crocs/">solid evidence</a> for this. It shows that sometimes stepping back and taking a broad look at evidence can reveal some interesting things.</p>
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<p><em>This is an edited version of a post that appeared on <a href="http://blogs.egu.eu/palaeoblog/2013/10/22/crocodiles-are-so-hard-they-even-eat-fruit/">Jon Tennant’s blog</a>.</em></p><img src="https://counter.theconversation.com/content/20061/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jon Tennant does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Seed dispersal by animals is important for plants to help them occupy new areas of land. Usually bugs, birds, or intrepid kittens do that job. Now we can add crocodiles to that list. A new study reviewed…Jon Tennant, PhD student, Imperial College LondonLicensed as Creative Commons – attribution, no derivatives.