Saltwater Molluscs

Coat-of-mail Chiton

admin — Mon, 10 Sep 2007 16:27:36 +0000

The Coat-of-mail Chiton is a mollusc that has a soft brown body enclosed in a small oval-shaped shell and can be found on the west and south-west coasts of England. It has the name ‘Coat-of-mail’ because it has eight overlapping plates on its shell which look like the plates of armour similar to those on a knight’s gauntlet. It can be found in shallow waters and in waters as deep as fifty metres where it firmly attaches itself onto the underside of rocks. It can sometimes be found in rock pools.

The Coat-of-mail Chiton is about three centimetres long and its body is protected by a shell which is usually a brown colour. Sometimes the shell can be a combination of colours such as off-white, pink, yellow-brown and olive-green with a marbling effect. The Coat-of-mail Chiton has a small mouth and very hard teeth which are used to grind food. It also has a very strong muscular foot which it uses to move along surfaces and also to attach itself firmly onto rocks. If it is removed, it curls itself up tightly to protect itself.

The Coat-of-mail Chiton lays its eggs directly into the water where they develop. Larvae hatch out of the eggs and become part of zooplankton for a while before they settle on the seabed to develop into adult Coat-of-mail Chitons.

Cockle (Common)

admin — Mon, 10 Sep 2007 16:28:09 +0000

The Common Cockle is also known as the Edible Cockle. It is a ‘bivalve’ mollusc which means it has a soft body enclosed in two hinged shells, just like the Common Oyster and the Common Mussel. Common Cockles can be found in sandy bays and estuaries all around England, but they are often difficult to detect because they bury themselves about five centimetres under the sand when they are not feeding or when the tide is out.

The two shells of the Common Cockle are the same shape and size with around twenty-five curved ribbed lines running along the surfaces. The shells are quite solid and thick with a width and length of around four centimetres. The outer surfaces of the shells can be an off-white, a yellowy white or a brownish white colour and the inner surfaces are usually white with brown or light purple markings. The Common Cockle has a long and powerful muscular foot which is often bent under the shell, but it straightens the foot when it wants to jump forward. Sometimes the foot can be as long as the shell.

Common Cockles release their eggs directly into the water where they develop and hatch. The newly hatched larvae become part of zooplankton for around three to six weeks and then they settle on sandy seabeds to develop into adult Common Cockles.

Cuttlefish (Common)

admin — Mon, 10 Sep 2007 16:28:41 +0000

The Common Cuttlefish is not a fish like its name suggests, but a ‘cephalopod’ . A cephalopod is a fast-swimming mollusc that has suckered tentacles attached to its head, just like the Lesser Octopus and the Common Squid. It can be found in inshore shallow waters throughout England during the summer months.

The Common Cuttlefish can reach a length of thirty centimetres and has about ten suckered tentacles with two of the tentacles being longer for seizing food. Its head is quite large and its body is broad and flattened which is ideal when this cuttlefish wants to rest on the seabed. It has large eyes with ‘W’ shaped black pupils. It also has an internal body shell known as the ‘cuttlebone’. Cuttlebones can often be seen washed up on our shores.

The Common Cuttlefish can swim backwards when it is in danger and it can also release a sort of ink-type dark fluid from its body when it feels very threatened. The inky fluid makes the water dark which confuses any predator. During the predator's confusion the Cuttlefish quickly escapes to safety. The Common Cuttlefish feeds on crabs, molluscs and small fish.

Mussel (Common)

admin — Wed, 19 Sep 2007 16:37:37 +0000

The Common Mussel is a ‘bivalve’ mollusc which means that it has a soft body enclosed in two hinged shell, like the Grooved Razor Shell and the Common Oyster. It can be found all around the coasts of England on rocky shores attached to rock surfaces. It can also be found attached to piers and is often seen in large groups known as ‘mussel beds’. Large masses of mussel beds can be found in Morecombe Bay and in the estuaries of south-west England.

The Common Mussel has an almost triangular-shaped shell which is usually a purplish or a bluish colour. Sometimes the shell can be brown. The inside of the shell is pearly white with a blue coloured edge. The soft body inside is an orangy colour. The Common Mussel has a large muscular foot which is usually the only part of the body that can be seen outside the shell. The foot can produce a hard thread called the ‘byssus’ thread which the Common Mussel uses to attach itself onto hard surfaces.

Common Mussels lay their eggs directly into the sea where they develop and hatch. The newly hatched larvae become part of zooplankton for around four weeks before they settle on seaweed for a short while. They eventually detach themselves from the seaweed and drift in the water on ‘byssus’ threads for a short time before joining mussel beds to develop into adult Common Mussels.

Octopus (Lesser)

admin — Mon, 10 Sep 2007 16:29:07 +0000

The Lesser Octopus is also known as the ‘curled octopus’ because it curls up its tentacles when it rests. It is a ‘cephalopod’ which is a fast swimming mollusc that has suckered tentacle-like arms attached to its head, just like the Common Cuttlefish and the Common Squid. It can sometimes be found along the rocky shores of England, but it is very rarely seen because it spends most of its life hiding in holes and crevices under the sea, especially in the day.

The Lesser Octopus is about fifty centimetres long and has a reddish coloured body covered in tiny wart-like bumps. It has eight powerful tentacle-like arms with one row of sucker pads on each arm which are used for catching prey and for crawling on surfaces. Its head is large and bulbous with two large eyes. It also has an almost beak-shaped jaw. This sea creature can see nearly as well as a human being can see.

The Lesser Octopus can release a sort of ink-type dark fluid from its body when it feels threatened. The inky fluid makes the water dark which confuses and disorientates any predator allowing the octopus to escape from danger.

Oyster (Common)

admin — Mon, 10 Sep 2007 16:29:34 +0000

The Common Oyster is also known as the Native Oyster and the Edible Oyster. It can be found in shallow waters on solid mud, muddy sand, gravel and rocks all around our English coast, although it is not so common in the east and north-east. It is a ‘bivalve’ mollusc which means it has a soft body enclosed in two hinged shells, like the Grooved Razor Shell and the Common Mussel.

The Common Oyster can reach a width of up to eleven centimetres and is almost pear-shaped with a rough, scaly shell that has ridged circular lines. The shell can be a grey-white, yellow-grey or a creamy brown colour with brown or bluish band-like markings on the ridges. The inside of the shell is a pearly white, yellow-grey or a creamy brown colour with random blue markings.

If sand, grit or a particle of food gets trapped in between the two hinged shells, the Common Oyster can feel this so it covers the foreign body with a shiny iridescent substance called ‘nacre’ to reduce the irritation. It repeatedly coats the ‘irritant’ with nacre which eventually forms a pearl. The pearl is often called the ‘Mother of Pearl’ and its size depends on the size of the foreign body that gets trapped inside the shell.

Razor Shell (Grooved)

admin — Mon, 10 Sep 2007 16:30:10 +0000

The Grooved Razor Shell is also known as the Common Razor Shell. It is a ‘bivalve’ mollusc which means it has a soft body enclosed in two hinged shells, like the Common Mussel and the Common Oyster. It can be found on most of our English shores, apart from the east coast shores and it has its name 'Razor Shell' because its shell looks like an old-fashioned hinged razor blade.

The Grooved Razor Shell has a long oblong-shaped shell which can be over ten centimetres long. The shell is smooth and is usually a yellow colour with pale brown or green markings. The soft body inside is usually a dull red colour. It has a tube-like fleshy coloured organ which juts out at one end of the shell. This organ is called the ‘siphon’ which is used when the Grooved Razor Shell wants to feed.

The eggs of the Grooved Razor Shell are laid directly into the sea where they develop and hatch. The newly hatched larvae become part of zooplankton for about a month before settling on the seabed to develop into adult Grooved Razor Shells.

Scallop (King)

admin — Mon, 10 Sep 2007 16:31:43 +0000

The King Scallop is also known as the Great Scallop. It is a large ‘bivalve’ mollusc which means it has a soft body enclosed in two hinged shells, like the Grooved Razor Shell and the Common Cockle. It can be found around most coasts of England in shallow and deep waters on firm sand or on fine and sandy gravel.

The King Scallop can grow up to twenty centimetres in diameter and its two shells have curved ribbed lines running along the surfaces. Both shells are fan-shaped even though the lower shell is deeply curved like a bowl and the upper shell is flat like a lid. The flat top shell is usually a pink or a reddish brown colour and the lower curved shell can be off-white, yellow or light brown. When the shells are slightly opened, a row of small white tentacles can be seen and between the tentacles small black eyes can be detected. The King Scallop uses its tentacles to touch, taste and smell.

King Scallops release their eggs directly into the water where they develop and hatch. The newly hatched larvae become part of zooplankton for about a month before settling on the seabed to develop into adult King Scallops.

Sea Hare

admin — Mon, 10 Sep 2007 16:36:56 +0000

The Sea Hare is a small sea creature that is often referred to as a ‘sea slug’. It can be found around many coasts of England where there is shallow water and sometimes it can be found in rock pools. It has tentacle-like organs on the rear end of its body that look similar to the ears of a hare and this is why it has the name ‘Sea Hare’. It is a ‘gastropod’ mollusc, like snails and slugs, and unlike a snail that has an external shell, the Sea Hare has an internal shell that can be seen through a hole in the Sea Hare’s body.

The Sea Hare can grow to twenty centimetres in length, although it usually averages around seven centimetres. It has a lumpy-looking body which can be olive, green, red or purple-black with grey-white mottling and blackish spots. It has two small tentacles on the front of its head and one flat broad tentacle on either side of its mouth. The tentacle–like organs at the rear of the Sea Hare’s body are used to eject a purple dye. This dye is ejected when the Sea Hare feels threatened or alarmed.

Sea Hares lay their eggs in masses of string-like gelatine which are attached to rocks, stones and sea lettuce. The larvae hatch out directly into the sea where they become part of zooplankton for around a month before settling on the seabed to develop into adult Sea Hares.

Sea Slug (Sea Lemon)

admin — Mon, 10 Sep 2007 16:37:26 +0000

The Sea Lemon Sea Slug is a large oval-shaped sea slug that is quite flat-looking. It has its name the ‘Sea Lemon Sea Slug' because of its lemon yellow colouring. It can be found around most of the coasts of England in shallow waters, but it can also be found in off-shore waters as deep as three hundred metres. It can easily be overlooked because it likes to hide under large rocks.

The Sea Lemon Sea Slug can grow up to twelve centimetres in length and although it is usually a yellow colour it can also be white, pink, green or brown with darker blotchy markings. The top part of this sea slug’s body is covered in wart-like bumps and it has two finger-like antennae at the front of its body. At the rear end of the body it has eight feathery gills that stand up from the body. It uses the feathery gills to breathe through.

Sea Lemon Sea Slugs are ‘hermaphrodites’ which means they are both male and female. Sea Lemon Sea Slugs lay their eggs in ribbon-like masses which are attached to rocks in a coil shape. The larvae hatch out in the sea where they become part of zooplankton for around three months. Then they settle on the seabed to develop into adult Sea Lemon Sea Slugs.

Squid (Common)

admin — Mon, 10 Sep 2007 16:37:51 +0000

The Common Squid is also known as the European Common Squid and it is a ‘cephalopod’. A cephalopod is a fast-swimming mollusc that has suckered tentacles attached to its head, just like the Common Cuttlefish and the Lesser Octopus. It is usually found offshore all around the coasts of England, although it is more commonly found on the south coast. It can sometimes be spotted in deep rock rocks and is often referred to as ‘calamari’.

The Common Squid can reach a length of thirty centimetres and has ten suckered tentacles attached to its head with two of the tentacles being longer for seizing food. Its head is quite large with two black eyes. It has an almost tubular-shaped flattened body and a long, internal pen-shaped shell which supports the Common Squid’s slender body.

The Common Squid can change its body colour to suit its surroundings so it can be a pale grey colour to a brown or purple colour and like the Common Cuttlefish it can release a sort of ink-type dark fluid from its body when it feels threatened. The inky fluid makes the water dark which confuses any predator. During the predator’s confusion the Common Squid quickly escapes to safety.

Violet Sea Snail

admin — Mon, 10 Sep 2007 16:38:17 +0000

The Violet Sea Snail is a small ‘pelagic’ snail which means that it lives in the open sea away from the seabed and away from shores. However, sometimes after strong storms it may be found washed up on shores in the west and south-west of England. This snail is quite unusual because it spends most of its life floating on the surface of the open sea. To keep afloat it creates a raft of bubbles from its own mucus and then hangs head down from the mucus so it can feed.

The Violet Sea Snail has a spirally. paper thin shell that is around three centimetres in diameter. It has about five spirals on the shell which are also known as ‘whorls’. The shell is a violet and a pale purple colour and its body is also a violet colour. If you pick this snail up from the beach, you could well get purple dye on your fingers.

Female Violet Sea Snails make bubble mucous rafts to lay their eggs on and after they have laid the eggs, the females release the rafts into the open sea. As soon as the young snails hatch out, they make their own rafts of bubbles to keep afloat. Violet Sea Snails can travel hundred of miles floating on sea currents.

Whelk (Common)

admin — Mon, 10 Sep 2007 16:38:42 +0000

The Common Whelk is a quite a large marine snail with a spiral shell. It can be found all around the coast of England in both shallow and deep waters on sandy and muddy sea beds, as well as on gravel and rock. Although this snail is quite common it is quite difficult to detect because it blends well into the background of its environment.

The Common Whelk has a grubby-looking, spiral shell which is a yellowy brown with lighter and darker markings around the spirals. The shell is attached to the whelk’s back. The shell can grow up to six centimetres in length and can reach a height of around ten centimetres. The front part of the shell has a broad opening which the snail quickly retreats into if it feels threatened. It closes the entrance with the back of its foot for more protection. The Common Whelk has two stubby-looking tentacles which stick out at the front of its head and it has a quite a long flat tail.

Common Whelks enclose their eggs in protective capsules which are attached onto rocks, shells and stones. The mass of capsules are a yellowy cream colour and a single capsule can contain up to a thousand eggs. Young whelks hatch out of the capsules and the empty masses of capsules, known as ‘sea wash balls’, can be seen washed up on our beaches.