Ocean swimmers often wax lyrical about the benefits of a regular dip in the salt water.
Maerl beds are the coral reefs of the British Isles. But like their tropical counterparts, they're threatened by climate change.
South Africa is home to four other seahorse species, but this was the first time a pygmy seahorse had been observed in South Africa, let alone Africa.
We don't know for sure which one is smarter, because not everyone agrees on what "intelligence" means. Both have their own special behaviours and skills and we can't say who is more intelligent.
Sea otters can break the shell on a shellfish by hitting it against a stone resting on their belly. This can look like clapping. Some even have a favourite stone they carry around in their armpits.
Nightvision, ejectable stomachs and regrowable arms mean starfish are more than meets the eye.
Besides wondrous creatures, new discoveries and spectacular filming, Sir David Attenborough's follow up to The Blue Planet comes with a stark warning about the future