It's not a fish
but what is it?
There are hundreds of animals in our home waters which are undeniably lacking in backbone but this doesn't mean they're not worth knowing. Are you man enough to try Paul Naylor's invertebrate quiz or are you just a moping mollusc that needs to pay more attention?

1 Distinctive member of a group of extremely simple animals. Yellow bumpy surface. Name comes from the way it excavates into limestone and shells, not from its humdrum existence. (Clumps any size up to 1m across)br>	2 Small anemone that occurs in many different colour schemes. Usually found in large numbers providing spectacular scenery on rock faces. (Up to 2.5cm across)	3 Beautiful anemone which loves areas of fast-flowing water and frequently festoons wrecks. Tall when fully extended. Usually white, orange or green. (Up to 30cm tall)	4 Large anemone with stout, powerful tentacles that can catch surprisingly large prey such as unwary fish. Found in numerous attractive colour schemes, often with striped tentacles. (Up to 20cm across)
5 Soft coral formed by colony of many tiny creatures. Occurs in white or orange forms but the latter seems virtually absent from southern Britain. Has a rather morbid name. (Up to 20cm tall)	6 Small anemone-like creature, widespread in UK waters despite its name. Doesn't have the building skills possessed by many of its relatives and leads a solitary life. (Up to 4cm across)	7 Resembles a nudibranch but has a far thinner body, appearing almost to flow over the seabed. Distinctive coloration. A very primitive animal. (Up to 3cm long)	8 Looks rather like a sea anemone, but is a different sort of animal. The tentacles, which are normally but not always white, obtain food and oxygen from the water and also carry sense organs. (Tentacle crown up to 5cm across)
9 Strange animal that is actually a worm. Covered in coarse hairs, some of which are iridescent. Lives in muddy areas. Its name presumably arises from its furry appearance. (Up to 20cm long))	10 Crab definitely built for strength rather than speed, with heavy body and claws but surprisingly short legs. Distinctive "pie-crust" edging to its shell. (Carapace up to 25cm across)	11Bright red eyes and vivid blue lines on claws and legs make this crab unmistakable. Fast and pugnacious, with obvious paddles on hind-most legs. (Carapace up to 10cm across)	12 This crab spends most of its time buried beneath the sand using its antennae like a snorkel to draw down water for breathing. Unusual carapace shape, longer than it is broad. (Carapace up to 5cm long)
13 Crustacean with flattened body and part crab/part lobster appearance. This particular species has very long claws and is commonly found peering out of silty crevices in Scottish waters. (Body up to 5cm long)	14Large crustacean with marvellous deep blue carapace. Has very powerful claws and is an active predator, scavenger and cannibal. (Up to 75cm long)	15Pretty animal that makes small pit in kelp frond where it lives. Shell is kelp-coloured but bright blue stripes tend to give its position away. Often found in groups. (Up to 2cm across)	16Distinctive little mollusc, often found eating sea squirts. Has shiny shell which is partially obscured by flaps of soft tissue. This tissue is patterned like leopard skin. (Up to 1.5cm long)
17Sea slug, usually brown or green. It is its ear-shaped tentacles which give rise to its name but it seems oddly appropriate that sea lettuce is a staple food in its diet. (Up to 25cm long)	18Large nudibranch with a fruity name, occurs in colours other than yellow! Lays a broad egg ribbon, often in the form of a rosette. Feeds on sponges. (Up to 12cm long)	19Mollusc with two halves to its shell (ie a bivalve). Usually rests in hollow on sea-bed but can swim to avoid starfish. It looks like a pair of clockwork false teeth when swimming. (Up to 15cm across)	20Colour-change artist second to none. Other skills include jet-propulsion and superb buoyancy control, the latter aided by white object which is found washed up on beaches. (Up to 30cm long)
21 Large starfish covered in prominent spines, usually pale blue. Very common in shallow water. Like many starfish, it is an active predator of animals like clams and mussels. (Up to 80cm across)	22 Prettily coloured starfish. Unlike most starfish which are actively carnivorous, it is thought to be a plankton feeder. This makes its odd name seem even more inappropriate. (Up to 20cm across)	23Starfish with many more arms than the normal five, it usually has between eight and 13. Its body is brightly coloured, often in rings of red and pink. Feeds on other starfish and sea cucumbers. (Up to 30cm across)	24Looks rather like a huge, fat worm but spiny skin gives clue to its starfish connections. Throws out sticky white threads when threatened, which gives it its name. (Up to 25cm long)
		Position your cursor over the photo to identify the invertebrate.
25Belongs to a group of creatures that seem simple but are actually related to more advanced animals including ourselves, though only the larval stage gives this away. Transparent skin gives this particular species its name. Lives in bunches. (Up to 2cm tall)	26 Same sort of animal as previous species but forms colonies which bear a distinctive pattern. The colonies can be found encrusting rocks or seaweed. Feeds by simply filtering sea water, like so many marine animals. (Colonies up to 10cm across)	SCORING 0-6 Sea-slug: Have you ever done any British diving? Did you have your eyes shut? Try harder next year. 7-13 Mollusc: There's just too many for you to get to grips with, aren't there? Keep trying, get yourself a guide book. 14-19 Cuttlefish: Not bad, with some more diving and a bit of studying you could yet transform yourself into a prize-winning lobster! 20-26 Lobster: Whoa, Mr Cousteau! Pretty good, aren't you? You're obviously a fan of these spineless underwater attractions.