The Echiura, or spoon worms, are a small group of marine animals. Once treated as a separate phylum, they are now considered to belong to Annelida. Annelids typically have their bodies divided into segments, but echiurans have secondarily lost their segmentation. The majority of echiurans live in burrows in soft sediment in shallow water, but some live in rock crevices or under boulders, and there are also deep sea forms. More than 230 species have been described. Spoon worms are cylindrical, soft-bodied animals usually possessing a non-retractable proboscis which can be rolled into a scoop-shape to feed. In some species the proboscis is ribbon-like, longer than the trunk and may have a forked tip. Spoon worms vary in size from less than a centimetre in length to more than a metre.
Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. Many have patterns of yellow, orange, red and green coloration. The foregut, stomach and intestine run a little below the midline of the body, the anus is at the tip of the tail, and the mouth is under the front. A little above the gut is the rhynchocoel, a cavity which mostly runs above the midline and ends a little short of the rear of the body. All species have a proboscis which lies in the rhynchocoel when inactive but everts to emerge just above the mouth to capture the animal's prey with venom. A highly extensible muscle in the back of the rhynchocoel pulls the proboscis in when an attack ends. A few species with stubby bodies filter feed and have suckers at the front and back ends, with which they attach to a host.
Anthozoa is a class of marine invertebrates which includes the sea anemones, stony corals and soft corals. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as part of the plankton. The basic unit of the adult is the polyp; this consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles. Sea anemones are mostly solitary, but the majority of corals are colonial, being formed by the budding of new polyps from an original, founding individual. Colonies are strengthened by calcium carbonate and other materials and take various massive, plate-like, bushy or leafy forms.
The acorn worms or Enteropneusta are a hemichordate class of invertebrates consisting of one order of the same name. The closest non-hemichordate relatives of the Enteropneusta are the echinoderms. There are 111 known species of acorn worm in the world, the main species for research being Saccoglossus kowalevskii. Two families—Harrimaniidae and Ptychoderidae—separated at least 370 million years ago.
Enopla is one of the classes of the worm phylum Nemertea, characterized by the presence of a peculiar armature of spines or plates in the proboscis.
The common sole, Dover sole, or black sole is a species of flatfish in the family Soleidae. It is one of the largest fish in the Solea genus. It lives on the sandy or muddy seabed of the northern Atlantic and the Mediterranean Sea where it often partially immerses itself in the substrate. The upper side is greyish-brown while the underside is white. It grows to a maximum length of about 70 cm (28 in). The species is prized as a food fish, being caught mostly by trawling on the seabed.
Listriolobus pelodes is a species of marine spoon worm. It is found in shallow seas in the North East Pacific off the coast of California. It lives in a burrow in soft sediments.
Cerianthus membranaceus, the cylinder anemone or coloured tube anemone, is a species of large, tube-dwelling anemone in the family Cerianthidae. It is native to the Mediterranean Sea and adjoining parts of the northeastern Atlantic Ocean.
Phyllodoce mucosa is a species of polychaete worm in the family Phyllodocidae. It is found intertidally in both the Pacific and Atlantic Oceans, typically on sandy or muddy seabeds.
Scolelepis squamata is a species of polychaete worm in the family Spionidae. It occurs on the lower shore of coasts on either side of the Atlantic Ocean.
Saccoglossus bromophenolosus is a species of acorn worm occurring in the northwestern Atlantic Ocean and the northeastern Pacific Ocean. It grows to a length of about 20 cm (8 in) and lives in a burrow in soft sediment in the intertidal and subtidal zones. The scientific name refers to 2,4-dibromophenol, a secondary metabolite present in this worm.
Tubulanus polymorphus is a species of ribbon worm in the phylum Nemertea. It is found in the northern Atlantic Ocean and the northern Pacific Ocean. It occurs on the lower shore down to about 50 m (160 ft), on sand or gravel, under stones and among seaweed.
Tubulanus superbus, commonly known as the football jersey worm, is a species of ribbon worm in the phylum Nemertea. Found in the northern Atlantic Ocean, the North Sea and the Mediterranean Sea, it occurs from the lower shore down to about 80 m (260 ft), on sand or gravel.
Cerebratulus marginatus is a proboscis worm in the family Lineidae. This ribbon worm has an Arctic distribution, and in the North Atlantic Ocean ranges as far south as Cape Cod and the Mediterranean Sea while in the Pacific Ocean it extends southwards to California.
Holothuria fuscocinerea, the ashy pink sea cucumber, is a species of sea cucumber in the family Holothuriidae. It is placed in the subgenus Stauropora, making its full name Holothuria (Stauropora) fuscocinerea. It is native to shallow water in the tropical and sub-tropical Indo-Pacific.
Urechis caupo is a species of spoon worm in the family Urechidae, commonly known as the innkeeper echiuran, the fat innkeeper worm, the innkeeper worm, or the penis fish. It is found in shallow water on the west coast of North America, between southern Oregon and Baja California, where it forms a U-shaped burrow in the sediment and feeds on plankton using a mucus net.
Ochetostoma erythrogrammon is a species of spoon worm in the family Thalassematidae. It is found in shallow water in the Atlantic Ocean, the Mediterranean Sea, and the Indian and Pacific Oceans, burrowing in soft sediment.
Maxmuelleria lankesteri is a species of spoon worm in the family Bonelliidae. It is found in the North Atlantic Ocean. It burrows into soft sediment on the seabed, mostly in deep water.
Themiste pyroides is a species of unsegmented benthic marine worm in the phylum Sipuncula, the peanut worms. It occurs in the intertidal zone and shallow water in the western Atlantic Ocean and the northeastern Pacific Ocean. It lives in crevices and under rocks, extending its "crown" of branching tentacles into the surrounding water to feed.
Phyllodoce lineata is a species of polychaete worm in the family Phyllodocidae. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea where it occurs in the intertidal and shallow sub-tidal zones on soft sediment.
