Bryozoa are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about 0.5 millimetres long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The bryozoans are classified as the marine bryozoans (Stenolaemata), freshwater bryozoans (Phylactolaemata), and mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. 5,869 living species are known. Originally all of the crown group Bryozoa were colonial, but as an adaptation to a mesopsammal life or to deep‐sea habitats, secondarily solitary forms have since evolved. Solitary species has been described in four genera; Aethozooides, Aethozoon, Franzenella and Monobryozoon). The latter having a statocyst‐like organ with a supposed excretory function.
The Sipuncula or Sipunculida is a class containing about 162 species of unsegmented marine annelid worms. Sipuncula was once considered a phylum, but was demoted to a class of Annelida, based on recent molecular work.
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.
Alvinella pompejana, the Pompeii worm, is a species of deep-sea polychaete worm. It is an extremophile found only at hydrothermal vents in the Pacific Ocean, discovered in the early 1980s off the Galápagos Islands by French marine biologists.
Lophotrochozoa is a clade of protostome animals within the Spiralia. The taxon was established as a monophyletic group based on molecular evidence. The clade includes animals like annelids, molluscs, bryozoans, and brachiopods.
The lophophore is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Hyolitha, and Phoronida, which collectively constitute the protostome group Lophophorata. All lophophores are found in aquatic organisms.
Phoronids are a small phylum of marine animals that filter-feed with a lophophore, and build upright tubes of chitin to support and protect their soft bodies. They live in most of the oceans and seas, including the Arctic Ocean but excluding the Antarctic Ocean, and between the intertidal zone and about 400 meters down. Most adult phoronids are 2 cm long and about 1.5 mm wide, although the largest are 50 cm long.
Brachiopods, phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachiopods, a stalk-like pedicle projects from an opening near the hinge of one of the valves, known as the pedicle or ventral valve. The pedicle, when present, keeps the animal anchored to the seabed but clear of sediment which would obstruct the opening.
Phoronopsis is a genus of horseshoe worm in the family Phoronidae, in the phylum Phoronida. The members of the genus live in tubes at the bottom of the sea.
Phoronis psammophila is a species of marine horseshoe worm in the phylum Phoronida. It lives in a tube projecting from the sea floor in shallow seas around the world.
Phoronopsis californica is a species of marine horseshoe worm in the phylum Phoronida. It was first described as a new species by William Hilton in 1930 when he found it at Balboa Bay in Newport Beach, California.
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.
Phoronis australis is a species of marine horseshoe worm in the phylum Phoronida. It is found in shallow warm-temperate and tropical waters in the eastern Atlantic Ocean and the Indo-Pacific region and was first detected in the Mediterranean Sea in the late twentieth century. These worms live in association with tube-dwelling anemones, particularly those in the genus Cerianthus.
Phoronis ovalis is a species of marine horseshoe worm in the phylum Phoronida. It is found in shallow waters in the northeastern Atlantic Ocean, the southeastern Atlantic Ocean, Argentina, and other scattered locations worldwide. These worms secrete a tube into which they can retreat, and burrow into the shells of molluscs.
Phoronis embryolabi is a species of marine horseshoe worm in the phylum Phoronida. It is found in Vostok Bay, where it lives together with Nihonotrypaea japonica, an Axiidea shrimp species, in its burrows.
Phoronis emigi is a species of marine horseshoe worm in the phylum Phoronida. It is found off the coast of Japan and is morphologically similar to Phoronis psammophila.
Phoronis ijimai is a species of marine horseshoe worm in the phylum Phoronida.
Phoronis muelleri is a species of marine horseshoe worm in the phylum Phoronida. Like most phoronids, Phoronis muelleri has a biphasic life-cycle consisting of a pelagic larval stage, the actinotrocha, and a benthic, sessile adult stage.
Phoronis savinkini is a species of marine horseshoe worm in the phylum Phoronida. It is found in the Gulf of Tonkin. The holotype was collected off the coast of Vân Đồn District, Quang Ninh Province in northern Vietnam.
Phoronopsis harmeri is a species of marine horseshoe worm in the phylum Phoronida. It was first described by H.L.M. Pixell in 1912, and was found off of Vancouver Island.
