tag:theconversation.com,2011:/global/topics/feeding-habits-2539/articlesFeeding habits – The Conversation2024-02-21T19:01:08Ztag:theconversation.com,2011:article/2239192024-02-21T19:01:08Z2024-02-21T19:01:08ZTracking tropical turtles deep down to the seabed reveals their feeding habits<p>Hawksbill turtles are <a href="https://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T8005A12881238.en">critically endangered</a>, they are found in every ocean and are the most tropical of sea turtles. Adult hawksbills have long been considered to have a close association with shallow (less than 15 metres depth) seas where coral reefs thrive.</p>
<p>But <a href="https://www.doi.org/10.1126/sciadv.adl2838">new research</a> my colleagues and I conducted reveals for the first time that hawksbill turtles feed at reef sites much deeper than previously thought. </p>
<p>Young hawksbills drift in currents during their pelagic (open water) phase of their development before they move to benthic (sea bed) habitats. Hawksbills are usually seen foraging in coral reefs where their diet is predominantly <a href="https://doi.org/10.3354/meps245249">sponges</a>. They also feed on a variety of algae, corallimorphs (coral-like anemones), tunicates and <a href="https://www.ajol.info/index.php/wiojms/article/view/66534">more</a>. </p>
<p>To study their feeding habits in more detail, my team at Swansea University used high-accuracy global positioning system (GPS) satellite tags to track 22 adult female hawksbills from their nesting site on Diego Garcia in the Chagos archipelago in the Indian Ocean to their foraging grounds. </p>
<p>Three of the tags included a pressure transducer that was programmed to record depth every five minutes and relay the measurement to the satellite system every time the turtle surfaced. This gave us information about the whereabouts of the turtles and how deep they were diving to feed as they swam.</p>
<p>We predicted that hawksbills tracked in our study would probably migrate to shallow coral reefs around the seven atolls of the Chagos archipelago. Many studies have shown the <a href="https://www.nature.com/articles/srep18289">pristine nature of these reefs</a> and we have previously observed hawksbills frequently foraging in reef habitats there. </p>
<p>But, surprisingly, all turtles migrated to deep, remote banks and submerged reefs in the archipelago, remaining at these deep sites for more than 6,000 combined days of tracking. By looking at nautical charts for the turtle locations, we could see that the foraging habitat was located at more than 30 metres depth. </p>
<p>More than 183,000 depth measurements relayed from the tags on three turtles showed that average depths were between 35 metres and 40 metres. <a href="https://doi.org/10.1126/sciadv.adl2838">Most dives reached depths between 30 metres and 60 metres</a>. That’s much deeper than we expected.</p>
<h2>Crucial for conservation</h2>
<p>The coral reefs located at depths of between 30 metres and 150 metres below the waves are known as mesophotic (or low light) ecosystems. Now, knowing that these habitats are so crucial for critically endangered sea turtles suggests that the marine life deep down on the seabed is much richer – with more nutritious food for turtles to eat – than previously thought. </p>
<p>We’d expect to find an abundance of colourful sponges and other invertebrate prey items such as soft corals that make up a big portion of the hawksbills’ diet. Our finding adds to the growing evidence that submerged banks at these mesophotic depths might be home to a diverse community of life, including <a href="https://www.ajol.info/index.php/wiojms/article/view/209266">sponges</a> and <a href="https://doi.org/10.1016/j.marpolbul.2018.03.018">seagrass</a> that are key foods for green turtles that also breed and forage in the western Indian Ocean. </p>
<p>Mesophotic ecosystems cover a vast area so they should be a significant part of conservation considerations. We estimated that submerged banks (at depths of 30 to 60 metres) in the western Indian Ocean extend across over 55,000 km² - around three times the size of a small country such as Wales.</p>
<p>Scientific understanding of mesophotic ecosystems is very poor, partly because they are difficult to explore. They are usually remote and far from land, plus the depths are often beyond the limit of routine scientific scuba diving. </p>
<p>There’s huge scope for more fascinating research to investigate the ecology of these misunderstood marine habitats. Recent studies have suggested <a href="https://doi.org/10.1371/journal.pone.0177374">rich biodiversity</a> and <a href="https://www.nature.com/articles/s41598-017-03568-1">abundant fish</a>, <a href="https://link.springer.com/article/10.1007/s00338-010-0593-6">corals and sponges</a> live at depths over 30 metres. </p>
<h2>Reef refuges</h2>
<p>With the pressures of climate change and warming seas, mesophotic reefs could be a refuge for corals and sponges that normally live in shallow coral reefs. For example, coral cover in Caribbean mesophotic reefs (30 to 40 metres depth) remained constant during hurricanes, bleaching and disease events in 2017 to 2019 when coral cover declined in shallow- and mid-water depths. That demonstrates the importance of these mesophotic reefs as a <a href="https://link.springer.com/article/10.1007/s00338-021-02087-w">reproductive refuge for corals</a>.</p>
<p>Our study findings highlight that submerged banks and mesophotic depths are important foraging grounds for critically endangered marine animals such as turtles and may support a rich array of marine life. While the mesophotic reefs used by foraging hawksbills in our study lie within one of the world’s largest marine protected areas, with <a href="https://doi.org/10.1007/s00227-020-03776-w">protection from industrial fishing</a>, there are ongoing negotiations for future conservation management of this region. </p>
<p>These submerged banks in the Chagos archipelago, and probably others around the world, should be key areas for conservation focus. The resilience of marine ecosystems, and all that lives within them, may rely on the health of these deeper, uncharted habitats, especially in the face of climate change.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 30,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/223919/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicole Esteban receives funding from the Bertarelli Foundation as part of the Bertarelli Programme in Marine Science (grant numbers BPMS-2017-4 and 820633).</span></em></p>Deeper ocean habitats (30-150 metres) are a key feeding ground for critically endangered hawksbill turtles.Nicole Esteban, Associate Professor of Marine Biology, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1299612020-01-17T12:32:49Z2020-01-17T12:32:49ZLet babies be in charge of how much they eat – it could help them stay a healthy weight<figure><img src="https://images.theconversation.com/files/310281/original/file-20200115-134784-d8ea7d.jpg?ixlib=rb-1.1.0&rect=62%2C55%2C4539%2C3393&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Don't mind the mess.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/baby-girl-eating-vegetable-first-time-577712248">shutterstock/Mcimage</a></span></figcaption></figure><p>How babies are fed is often a topic of hot discussion. It’s known that babies should be introduced gradually to solid foods <a href="https://www.nhs.uk/conditions/pregnancy-and-baby/solid-foods-weaning/">at around six months old</a>. But in recent years, another question has arisen: should parents be spoon-feeding babies special pureed baby foods or could they just join in <a href="https://www.theguardian.com/commentisfree/2012/feb/08/baby-led-weaning">with the family and feed themselves</a> from the very start?</p>
<p>Known as <a href="http://www.babyledweaning.com">baby-led weaning</a>, parents who follow the method believe it has lots of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1740-8709.2011.00360.x">benefits for their baby</a>, such as encouraging them to eat a range of foods and stay a healthy weight. Research suggests that babies who feed themselves are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.2047-6310.2013.00207.x">less likely to be fussy</a> and more likely to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/jhn.12616">eat a wider variety of food</a>. But what about their weight? </p>
<p>Research examining this so far <a href="https://link.springer.com/article/10.1007/s13668-017-0201-2">has been mixed</a>. But in <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/mcn.12941">our new study</a> of 269 babies, we found that when babies were breastfed, there was no difference in weight for those who were spoon-fed or self-fed. But when babies were bottle fed, those who were spoon-fed were heavier than those who self-fed. </p>
<p>This is potentially because as long as babies have some opportunity to be “in charge” of how much they eat, they may be better able to eat according to what they need rather than how much food a caregiver might encourage them to eat.</p>
<h2>Milk matters too</h2>
<p>Previous research into the impact of solid foods and weight has not really explored how the other part of a baby’s diet – their milk feeds – might play a role. </p>
<p>Indeed, solid foods should only be part of a baby’s diet. Babies who are between six and 12 months should still be getting lots of energy <a href="https://www.unicef.org/parenting/food-nutrition/feeding-your-baby-6-12-months">from breast or formula milk</a>. In fact, at six to eight months old, babies only need <a href="https://static1.squarespace.com/static/59f75004f09ca48694070f3b/t/5ceed06a15fcc07f8822270b/1559154825802/Eating_well_first_year_April19_for_web.pdf">less than 200 calories a day</a> from solid foods. </p>
<p>Research with older children shows that using a “<a href="http://www.aijcrnet.com/journals/Vol_7_No_2_June_2017/9.pdf">responsive feeding style</a>”, where lots of healthy options are offered but parents don’t put too much pressure on how much children eat, is associated with <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2015.01849">a healthier weight and more varied diet</a>. Children are better able to listen to their own hunger cues and don’t crave foods that are “banned” so much – meaning they are less likely to overeat. </p>
<p>Research with younger babies shows that <a href="https://kellymom.com/ages/newborn/bf-basics/importance-responsive-feeding/">being “responsive” during milk feeds</a> also matters. For example, bottle fed babies who are fed responsively – with parents looking for cues they are full – <a href="https://www.ncbi.nlm.nih.gov/pubmed/3572635">drink less than those who are encouraged to finish a bottle</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310284/original/file-20200115-134768-5cbe8d.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">
<figcaption>
<span class="caption">Breastfeeding allows babies to self-regulate.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/horizontal-shot-happy-young-mixed-race-1104404429">shurkin_son/Shutterstock</a></span>
</figcaption>
</figure>
<p>Breastfeeding might <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0083893">make responsive feeding easier</a> as you cannot see how much a baby has drunk, so you have to trust they will feed if they are hungry. It’s also difficult to persuade a baby who doesn’t want to breastfeed to do so. But if you are bottle feeding you can see how much is left and might worry that baby <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-277X.2010.01145.x">needs to finish the bottle</a>. </p>
<p>This might explain why babies who are breastfed are more likely to be able <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.2047-6310.2012.00071.x">to control their appetite</a> as toddlers and are <a href="https://www.tandfonline.com/doi/abs/10.3109/17477160902763309">less likely to be overweight</a>. </p>
<h2>Feeding your baby responsively</h2>
<p><a href="http://orca.cf.ac.uk/91927/">Decisions around feeding babies are complicated</a> and some mothers <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jan.12832">might face challenges breastfeeding</a> or <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/mcn.12166">worry about giving their baby solid foods</a>. But the good news is that most babies, unless there is a particular medical worry about their growth, should be able to have opportunity to be “in charge” of how much they eat. </p>
<p>If you are bottle feeding, try not to worry too much about when and how much your baby feeds. Instead, try <a href="https://www.unicef.org.uk/babyfriendly/baby-friendly-resources/bottle-feeding-resources/infant-formula-responsive-bottle-feeding-guide-for-parents/">“paced” or “responsive” feeding</a>, where smaller amounts of milk are made up and you watch carefully for signs your baby is full. </p>
<p>To do this gently, offer your baby the bottle by stroking their lip and wait for them to show they are ready –- they will open their mouth if they are hungry. Pause regularly and stop when your baby starts to show signs of being full, such as turning their head or pushing the bottle out. Don’t try to encourage them to finish the bottle. </p>
<p>If you are spoon-feeding, <a href="https://www.nhs.uk/conditions/pregnancy-and-baby/solid-foods-weaning/">let your baby set the pace of the meal</a>. Offer them small spoonfuls and, again, pause in between, looking for signs they have had enough such as turning their head or pushing lots back out. Don’t try to persuade them to finish a jar or eat too quickly. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310466/original/file-20200116-181617-aokkjo.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">
<figcaption>
<span class="caption">Feeding themselves allows babies to be more in control of the pace and amount they eat.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-father-feeding-his-son-park-408647689">Air Images/Shutterstock</a></span>
</figcaption>
</figure>
<p>Remember, guidelines suggest that however you feed your baby you <a href="https://www.nhs.uk/conditions/pregnancy-and-baby/solid-foods-weaning/">can give them finger foods from the start of weaning</a>. Try foods such as soft cooked sticks of parsnip, broccoli or yam, flakes of fish or toast fingers. Cut food into pieces large enough for them to pick up, so that the food sticks out of the top of their fist. But make sure you avoid foods that could snap off in your baby’s mouth such as hard apple slices or raw carrot sticks or small hard foods such as nuts or popcorn. </p>
<p>Some babies might not eat much at first when they self-feed, but don’t worry. Remember, the <a href="https://link.springer.com/article/10.1007/s13679-018-0297-8">experience of learning to eat is important too</a>. Letting babies play with food, feeling its texture and learning how it tastes is all part of their development – just put a mat down and try not to worry too much about the mess!</p><img src="https://counter.theconversation.com/content/129961/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sara Wyn Jones received funding from Swansea University for her PhD research.</span></em></p><p class="fine-print"><em><span>Amy Brown has previously received research funding from the ESRC, NIHR, Public Health Wales, the Breastfeeding Network and First Steps Nutrition Trust. She is author of four books published by Pinter and Martin Ltd - 'Breastfeeding Uncovered: who really decides how we feed our babies', 'Why starting solids matters' , 'The Positive Breastfeeding Book', "Informed is best', 'Why breastfeeding grief and trauma matter' alongside a Routledge textbook 'A guide to breastfeeding for the medical profession'. </span></em></p><p class="fine-print"><em><span>Michelle Lee receives funding from the BBSRC. </span></em></p>It’s important for babies to be in control of the pace and amount they eat.Sara Wyn Jones, PhD researcher in Public Health, Swansea UniversityAmy Brown, Professor of Child Public Health, Swansea UniversityMichelle Lee, Professor of Psychology, Swansea UniversityLicensed 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">
<figcaption>
<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>
</figcaption>
</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">
<figcaption>
<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>
</figcaption>
</figure>
<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/737702017-03-01T19:13:14Z2017-03-01T19:13:14ZWhen mammals took to water they needed a few tricks to eat their underwater prey<figure><img src="https://images.theconversation.com/files/158680/original/image-20170228-29942-vui9en.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A baleen whale feeding in the Hauraki Gulf, New Zealand.</span> <span class="attribution"><span class="source">Dr Krista Hupman</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Have you ever watched a dog retrieve a ball thrown into water? On land, dogs are swift and agile, but in water they become slow and ungainly.</p>
<p>Kicking relentlessly at the water, they snap at the ball with their jaws, only to find that they are pushing it further away. Having eventually caught the ball, they inevitably go into a fit of coughing and sneezing, as they try to shake off water from their nose and face. </p>
<p>Most other mammals have a similarly hard time in water. Yet a select few have come to dominate the world’s rivers and seas, from the poles to the Equator and from the water’s surface to the depths of the abyss. </p>
<p>To achieve this, mammals had to learn to swim, to keep warm, and to find, capture and handle their prey in water. </p>
<p>How aquatic mammals have adapted to feed underwater is the subject of a new research article published this week in <a href="http://rspb.royalsocietypublishing.org/content/284/1850/20162750">Proceedings of the Royal Society B</a>. </p>
<p>In this study, we originally set out to review the feeding behaviours of all carnivorous aquatic mammals – creatures as varied as sleek otters, agile seals and dolphins, and filter-feeding whales. To our surprise, we discovered that all of these animals are linked by a simple evolutionary pattern. </p>
<h2>The need to feed in water</h2>
<p>Despite their obvious differences, when feeding in water all mammals appear to follow just six well-defined, interrelated and increasingly specialised strategies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=265&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=265&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=265&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158681/original/image-20170228-29906-kh5i1p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sequence of increasingly aquatic feeding strategies used by mammals when eating underwater.</span>
<span class="attribution"><span class="source"> Illustrations by Carl Buell</span></span>
</figcaption>
</figure>
<p>The ancestors of aquatic mammals started out as terrestrial feeders, using their teeth and claws to catch and process their food entirely on land. </p>
<p>Over time, some parts of the feeding process began to happen underwater, while others still occurred at the surface, giving rise to semi-aquatic feeding.</p>
<p>For example, modern otters hunt fish underwater using their jaws and paws, but they then bring their catch to the surface to process it with their teeth. </p>
<p>As mammals became more aquatic, they began feeding entirely underwater. Seals and dolphins are capable of catching, handling and swallowing food beneath the waves. Like their terrestrial and semi-aquatic cousins, these raptorial feeders still primarily rely on their teeth to pierce and hold their prey.</p>
<p>To make sure that captured prey does not float away before swallowing, they then suck their food deeper into the mouth by pulling back their tongue.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=568&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=568&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=568&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=713&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=713&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158807/original/image-20170228-13104-l74cs0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=713&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Australian sea lion capturing a fish in its teeth during underwater feeding.</span>
<span class="attribution"><span class="source">David Hocking</span></span>
</figcaption>
</figure>
<h2>The suckers</h2>
<p>Building on this need to generate suction, some species took advantage of the ability to manipulate water flow, and became specialist suction feeders.</p>
<p>Animals that use this strategy – including certain seals, sperm whales and beaked whales – largely do away with teeth. Instead they “hoover” prey directly into their mouth, often from a considerable distance, or even from the sea floor. </p>
<p>Because suction feeding does not rely on teeth to pierce individual prey items, it allows the capture of relatively small prey. But as prey gets smaller, it also becomes more difficult to retain inside the mouth.</p>
<h2>The filterers</h2>
<p>Suction filter feeders solve this problem by using a specialised filter, such as the elaborate teeth of crabeater and <a href="https://link.springer.com/article/10.1007/s00300-012-1253-9">leopard seals</a>, or the comb-like baleen plates of grey whales. They then strain small prey like krill from water sucked into the mouth. </p>
<figure>
<iframe src="https://player.vimeo.com/video/206018882" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Leopard seal using suction feeding to capture a small fish and semi-aquatic feeding to process a large fur seal.</span></figcaption>
</figure>
<p>Ram-based filter feeders, including rorquals like the blue and humpback whales, retain a specialised filter but do away with suction. They filter small prey directly from large mouthfuls of seawater.</p>
<p>All of these strategies are flexible in that a single animal may switch between them when feeding on different kinds of prey. For example, a leopard seal may use semi-aquatic or raptorial feeding when hunting penguins, but suction filter feeding when preying on krill.</p>
<p>Nevertheless, any single feeding event will only follow one feeding strategy at a time: after all, a leopard seal cannot filter a penguin.</p>
<h2>Behaviour informs evolution</h2>
<p>The six strategies defined here naturally grade into each other, and together form a sequence that recalls the evolutionary transition of mammals back to the sea. </p>
<p>Some species can cross the boundaries between strategies, but only when one strategy is derived from the next, like semi-aquatic from terrestrial, or suction from raptorial feeding. Thus, for example, fur seals can <a href="http://onlinelibrary.wiley.com/doi/10.1111/mms.12285/full">switch between the semi-aquatic, raptorial and suction strategies</a> when targeting prey of different sizes. </p>
<figure>
<iframe src="https://player.vimeo.com/video/206017099" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Australian fur seals vary their feeding strategy when targeting different sized prey.</span></figcaption>
</figure>
<p>Being able to read evolutionary history from the feeding behaviour of living mammals allows us to explain and make predictions about how the fossil ancestors of these modern species may have behaved. </p>
<p>For example, we might predict that modern baleen whales must have evolved from raptorial ancestors via a suction-feeding intermediate. Recent discoveries, such as that of a <a href="https://theconversation.com/how-alfred-the-whale-lost-its-teeth-to-become-a-giant-filter-feeder-69489">suction feeding, toothed fossil “baleen” whale</a>, seem to bear this out.</p>
<p>So imagine again a dog, struggling with the ball in the water. If we wanted to engineer it to perform better next time, these are the stages we’d have to go through: teach Rex to capture the ball underwater; next, teach him to handle the excess seawater; finally, teach him to suck the ball towards his snout, rather than accidentally pushing it away. </p>
<p>The same process happened for real at least three times in the evolutionary history of mammals. Who knows where it might go next – suction-feeding otters, anyone?</p><img src="https://counter.theconversation.com/content/73770/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Hocking receives funding from an Australian Research Council Linkage Project (LP150100403). He is affiliated with Monash University and Museums Victoria, Melbourne, Australia.</span></em></p><p class="fine-print"><em><span>Felix Georg Marx receives funding through an EU Marie Skłodowska-Curie Global Postdoctoral fellowship (656010/MYSTICETI).
He is affiliated with the Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Monash University, Melbourne, Australia; and Museums Victoria, Melbourne, Australia.</span></em></p><p class="fine-print"><em><span>Travis Park is affiliated with Monash University, Melbourne, Australia and Museums Victoria, Melbourne, Australia. </span></em></p>There are plenty of mammals that have adapted to life in water, some more than others. That meant they also had to adapt the way they feed.David Hocking, Research associate, Monash UniversityFelix Georg Marx, Post doctoral research fellow in evolutionary biology, Monash UniversityTravis Park, PhD student, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/262072014-05-02T05:07:16Z2014-05-02T05:07:16ZSix bizarre feeding tactics from the depths of our oceans<figure><img src="https://images.theconversation.com/files/47576/original/xdzpvgz2-1398962117.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Beautiful outside, monster inside.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/54945394@N00/2445410097">dachalan</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Sea life can be fascinating and terrifying at the same time. Some creatures look beautiful on the outside but harbour darkness within. Some of the scariest tactics of the deep sea go on display when these creatures eat. Here are six of my favourite feeding strategies:</p>
<h2>1. Jellyfish</h2>
<p>Jellyfish, corals and anemones are all cnidarians that have stinging cells on their tentacles called nematocysts. Jellyfish slowly drift along in the currents, swimming gracefully by inflating and deflating their bells, and catching unsuspecting creatures that drift by in these stinging tentacles. Food is then transferred into the digestive tract by oral tentacles that ring the mouth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=316&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=316&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=316&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=397&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=397&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47582/original/wn4n2yyg-1398968718.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=397&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Brad Erisman and NOAA</span></span>
</figcaption>
</figure>
<h2>2. Pink and yellow sea cucumber</h2>
<p>Speaking of tentacles, another cool way to catch a meal can be seen in the <a href="http://galleries.neaq.org/2011/05/pink-and-yellow-sea-cucumber.html">pink and yellow sea cucumber</a> and its relatives. This type of sea cucumber finds a good spot where water is flowing then holds its frilly tentacles out to capture food particles as they float by. It then gracefully plunges each tentacle individually into its mouth and pulls off all of the delicious edible bits. It’s like eating with a rotating collection of flexible forks.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_qV8qnA1WYY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Credit: Eleanor Richards.</span></figcaption>
</figure>
<h2>3. Feather stars</h2>
<p>Sea cucumber tentacles are akin to the mucus-coated tube feet used by their cousins, the feather stars. They hold their arms aloft, each tube foot stretched out and sticky, ready to catch some snacks. Passing plankton, bacteria and detritus gets trapped in the mucus and after a fair bit of arm waiving it’s time to gather the goods.</p>
<p>The tube foot furthest from the feather star’s mouth bends down to get closer to its neighbouring foot, which wraps itself around the first, sweeping it and bringing with it a sticky picnic. The foot below that does the same: wrapping itself around its neighbour and scraping the food off the end. It then delivers the meal to the feather star’s mouth.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=240&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=240&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=240&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=302&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=302&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47573/original/xp3mms92-1398960713.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=302&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<h2>4. Larvaceans</h2>
<p>There are more animals that make the most of mucus to catch a meal, such as larvaceans. They tend to be a few centimetres long and look a lot like a tadpole, with a round body at one end and a long tail at the other. On their own they are not the most inspiring of creatures, but the way they dine is definitely worth a mention.</p>
<p>Each larvacean builds it’s own mucus house that serves as a filter for the ocean’s fine foods. Their beating tail creates a current that keeps this sticky net open and brings in the grub. To deal with filters getting clogged, larvaceans simply throw out the old house and create a new one roughly every hour, ready to trap more tasty morsels.</p>
<p>The discarded house goes on to make a delicious meal for deep sea animals, rapidly falling to the deep ocean because all the trapped material makes it pretty heavy. Most material falls slowly to the deep – and it’s often eaten up on the way, but larvacean creations fall so fast that deep sea critters can enjoy a packed lunch of pretty fresh food. </p>
<figure>
<iframe src="https://player.vimeo.com/video/32278043" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
</figure>
<h2>5. Humpback whales</h2>
<p>Humpback whales form groups and then carefully coordinate, blowing bubbles to corral schools of fish together into one spot. Once the schools are combined into one big ball of lunch, the whales swim upwards through the school of fish with their mouths open.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vJvfjiCTvq4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>6. Sea star</h2>
<p>Imagine a mussel feeling safe and secure in its shell. Suddenly, a purple sea star appears and starts prying open that shell, showing every intention of eating the tiny creature inside.</p>
<p>The good news is, mussel muscles are very strong so the sea star can only open the shell of its intended victim a tiny bit. The bad news is, sea stars have the ability to invert their stomachs. Even though it has only opened he mussel’s shell slightly, it can push its stomach out of its body through the tiny space, digesting it in its own home.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2DFXGafpGkQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure><img src="https://counter.theconversation.com/content/26207/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jessica Carilli blogs at Saltwater Science (<a href="http://www.nature.com/scitable/blog/saltwater-science">http://www.nature.com/scitable/blog/saltwater-science</a>)</span></em></p>Sea life can be fascinating and terrifying at the same time. Some creatures look beautiful on the outside but harbour darkness within. Some of the scariest tactics of the deep sea go on display when these…Jessica Carilli, Adjunct Professor, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.