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.
The gastrotrichs, commonly referred to as hairybellies or hairybacks, are a group of microscopic (0.06-3.0 mm), worm-like, pseudocoelomate animals, and are widely distributed and abundant in freshwater and marine environments. They are mostly benthic and live within the periphyton, the layer of tiny organisms and detritus that is found on the seabed and the beds of other water bodies. The majority live on and between particles of sediment or on other submerged surfaces, but a few species are terrestrial and live on land in the film of water surrounding grains of soil. Gastrotrichs are divided into two orders, the Macrodasyida which are marine, and the Chaetonotida, some of which are marine and some freshwater. Nearly 800 species of gastrotrich have been described.
The shipworms are marine bivalve molluscs in the family Teredinidae: a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into wood that is immersed in sea water, including such structures as wooden piers, docks and ships; they drill passages by means of a pair of very small shells (“valves”) borne at one end, with which they rasp their way through. Sometimes called "termites of the sea", they also are known as "Teredo worms" or simply Teredo. Carl Linnaeus assigned the common name Teredo to the best-known genus of shipworms in the 10th edition of his taxonomic magnum opus, Systema Naturæ (1758).
Sabellidae, or feather duster worms, are a family of marine polychaete tube worms characterized by protruding feathery branchiae. Sabellids build tubes out of a tough, parchment-like exudate, strengthened with sand and bits of shell. Unlike the other sabellids, the genus Glomerula secretes a tube of calcium carbonate instead. Sabellidae can be found in subtidal habitats around the world. Their oldest fossils are known from the Early Jurassic.
Macrodasyida is an order of gastrotrichs. Members of this order are somewhat worm-like in form, and not more than 1 to 1.5 mm in length.
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms.
Chaetonotidae is a family of gastrotrichs in the order Chaetonotida. It is the largest family of gastrotrichs with almost 400 species, some of which are marine and some freshwater. Current classification is largely based on shape and external structures but these are highly variable. Molecular studies show a high level of support for a clade containing Dasydytidae nested within Chaetonotidae.
Diuronotus aspetos is a species of large sized meiofaunal chaetonotid gastrotrich found in the North Atlantic. With Diuronotus rupperti, it is one of the only two species representing the genus Diuronotus.
Macrodasys caudatus is a species of microscopic worm-like metazoan in the family Macrodasyidae in the phylum Gastrotricha. It lives in the interstices between particles of sediment on the seabed in shallow water. It is found in the Indian Ocean, the northeastern Atlantic Ocean, the Mediterranean Sea and the North Sea.
Paradasys subterraneus is a Gastrotricha with a bodylength up to 0.6 mm. The species is marine.
Lepidodermella squamata is a freshwater species of minute worm in the phylum Gastrotricha.
Parasagitta elegans is a small arrow worm in the family Sagittidae, previously named Sagitta elegans
Parasagitta setosa is a small arrow worm in the family Sagittidae, previously referred to as Sagitta setosa. It is native to the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea, and also occurs in the Baltic Sea and the Black Sea.
Euphylliidae are known as a family of polyped stony corals under the order Scleractinia.
Polydora ciliata is a species of annelid worm in the family Spionidae, commonly known as a bristleworm. It is a burrowing worm and is found in the northeastern Atlantic Ocean and some other parts of the world.
Syllis ramosa is a species of polychaete worm in the family Syllidae. It is found in the deep sea where it lives within the tissues of a sponge. It was the first branching polychaete worm to be discovered, with each worm having a single head and multiple anuses.
Ramisyllis multicaudata is a species of polychaete worm in the family Syllidae. It was found in Darwin Harbour, Australia, where it was living within the tissues of a sponge of the genus Petrosia. It was the second branching species of polychaete worm to have been discovered, the first having been Syllis ramosa, a deep water species, more than a century earlier. In 2022, a second species in R. multicaudata's genus, Ramisyllis kingghidorahi, was described from specimens taken off the coast of Sado Island, Japan.
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.
Yungia aurantiaca is a species of flatworm in the family Pseudocerotidae. It is found in the temperate northeastern Atlantic Ocean and the Mediterranean Sea.
Thaumastodermatidae is a family of worms belonging to the order Macrodasyida.
