The sea hare (Aplysia punctata) got its name from its rounded shape and two long rhinopheres that project upwards and resemble the ears of a hare.
The lobster has long claws covered in hairs with striking red nippers. It is difficult to approach and can move extremely fast when disturbed.
There are more than 3,000 known species of nudibranch and new ones are discovered nearly ever day.
Sgarbhstac has been labelled a 'must do' for divers visiting St Kilda. You can see light streaming through the arch of the rock outcrop and its roof and walls are full of life.
Who would have thought this is what we enjoy served up on a plate with chips?
The threadlike body of the skeleton shrimp allows it to virtually disappear among seaweed.
Common sunstars can be found from the Arctic right down to the English channel and Pacific Coasts. Very small sunstars are sometimes found in rock pools.
The black brittle star can be found in waters as deep as 400 metres and often appears in large numbers with more than a hundred grouped together in a square metre.
The lesser octopus is also called the curled octopus because it curls up its tentacles when it rests.
They are usually found in rocky areas around the UK in shallow water and often among mussels.