Clam worms, sand worms, and tubeworms are found in oceans and seas worldwide. Three species of clam worms, sand worms, and tubeworms are listed by the World Conservation Union (IUCN). Mesonerilla prospera is listed as Critically Endangered, or facing an extremely high risk of extinction in the wild. Erythrina polychaeta is Vulnerable, or facing a high risk of extinction in the wild. The Palol…
Myzostomids are found in all oceans. Most myzostomids live in warm tropical waters on the bodies of sea lilies, sea stars, and their relatives. A few species are found in the Arctic and Antarctic oceans. They live in shallow waters to depths of over 9,840 feet (3,000 meters). Most species use their extended mouthparts to suck up food particles floating in the water around them. A few myzostom…
Earthworms are found worldwide. They do not occur in deserts, polar regions, or in strongly acid soils. A few species have been widely distributed by humans. Most earthworms live in the soil, but some prefer the mud along the shores of fresh or salty bodies of water. Depending on species, many earthworms live in the upper leaf litter layer, topsoil, or in deeper layers in the soil. Others liv…
Leeches live on all continents except Antarctica. One species of leech, the European medicinal leech, is listed by the World Conservation Union (IUCN) as Lower Risk, or at risk of becoming threatened with extinction in the future. They are threatened due to habitat loss and over-collecting. Other species with limited distributions may also be threatened. …
Beard worms live on the bottom of the Norwegian fjords and in the Atlantic, Caribbean, Pacific, Indian, Arctic, and Antarctic oceans. Beard worms live on the ocean floor on continental slopes and in deep ocean trenches. Some species are found only on decaying wood near deep sea geysers at depths of 328 to 32,808 feet (100 to 10,000 meters). These deep sea geysers are called hydrothermal vents…
Hydrothermal vent and cold seep worms are found on the ocean bottom at the east Pacific Rise, mid-Atlantic Ridge, Galápagos Rift, Okinawa Trough, Mariana Trough, and the Lau, Manus, and North Fiji Basins. They also live along the continental margins of North and South America, Spain, and in the Mediterranean Sea. These worms are not considered endangered or threatened. …
Peanut worms are found in all of the oceans. Peanut worms are found in both cold- and warm-water habitats, at all depths between the intertidal zone and 22,510 feet (6,860 meters). Some species live in burrows in sand or mud, while others live in rock crevices, empty seashells, or tubeworm tubes. Still others bore into rock or bone. Some species make their homes in mats of algae (AL-jee) or p…
Echiurans are found in all oceans. Echiurans eat bits of dead plants, animals, and microorganisms that live on sand, mud, and rock. Echiurans are not considered endangered or threatened. …
Velvet worms are found in Mexico, Central America, Chile, tropical West Africa, South Africa, southeast Asia, New Guinea, Australia, and New Zealand. All velvet worms live in leaf litter, under stones or logs, or in soil in moist and humid habitats, such as tropical and subtropical forests. Velvet worms are carnivores (KAR-nih-vorz), or meat eaters, and eat mainly insects, spiders, other arth…
Water bears are found on all continents and in all oceans. Water bears require water and are found in a wide variety of marine, freshwater, and terrestrial habitats. Some species live in hot, radioactive springs, while other live in ice caves formed by glaciers and other sheets of ice. Many marine species are found along beaches. Those living on land are found in primitive plants and plantlik…
Remipedes are found in underwater sea caves along the shores of the Bahamas, Canary Islands, Cuba, eastern Mexico, northwestern Australia, and the Indian Ocean. Remipedes live only in completely submerged sea caves near the shores of islands and some continents. They live with other cave-dwelling, or troglodytic (TRAH-gloh-DIH-tik), crustaceans and fish. They are predators and eat troglodytic…
Cephalocarids live on the east and west coasts of North and South America, the Caribbean Islands, New Caledonia, New Zealand, and Japan. Cephalocarids are usually found on or just below the surface of the muck that settles on the sea bottom, from shallow waters to depths of 5,250 feet (1,600 meters). This muck is rich in plant and animal materials. A few species are found in sand or the rubbl…
Leptostracans are found in all the world's oceans. Most leptostracans are found from seashores to depths of 1312.32 feet (400 meters), but one species lives in deep-sea waters at depths of more than 6,561 feet (2,000 meters). Although some species prefer open waters, most live on mud bottoms that have very little oxygen. Leptostracans stir up materials from the bottom and filter out bi…
Mantis shrimps live in the ocean off nearly all landmasses in tropical and subtropical waters. Most mantis shrimps prefer to live in shallow tropical or subtropical seas, but a few species live in cooler waters of the sub-Antarctic. They are usually found along the shore in habitats affected by the tides or just beyond. Some species dig or occupy abandoned burrows with several entrances in mu…
Bathynellaceans are found on all continents except Antarctica. They are not known to be from Central America, from islands that are volcanic in origin, and from some other islands, such as New Caledonia, Fiji, and the Caribbean islands. Bathynellaceans are found mostly underground near freshwater habitats or in caves. They are sometimes collected on the surface in waters that are fed by under…
Anaspidaceans are found only in southeastern Australia (including Tasmania), New Zealand, Chile, and Argentina. The larger species of anaspidaceans usually prefer to live in cool mountain streams, lakes, and swamps. Stream-dwelling species forage on boulders and smaller rocks on the stream bottom. Species living in swamps are found in the burrows of crayfish. Lake species live in mats of alga…
Krill are found in all oceans. Krill swim in water off the coast, out in the open ocean, and around polar ice. Most krill feed and mate close to the surface, but a few species live at depths of up to 16,404 feet (5,000 meters). Krill eat free-floating organisms known as plankton, which are microscopic plants and animals. No species of krill are listed by the World Conservation Union (IUCN) as…
Amphionids live in all oceans. Because they are found throughout the world, no distribution map is provided. Amphionids are marine and are most common near the equator. Young animals live with other plankton at depths of 90 to 300 feet (30 to 100 meters). Plankton is made up of free-floating, often microscopic, plant and animal life. Adult females have been found at depths of 5,577 feet (1,70…
Decapods are found worldwide. There are 197 species of decapods listed by the World Conservation Union (IUCN), most of which are species of freshwater crayfish that live in very small or limited habitats. They are especially vulnerable to habitat destruction and loss and may become threatened in the future. …
Mysids live on all continents and in all oceans. Most mysids are filter feeders. They strain tiny bits of plant and animal materials from the water as they swim over the bottom. These species also use their pincherlike claws to capture small animals when they are available. Prey items include small crustaceans and mollusks. …
Lophogastrids live in all oceans except the Arctic. Most species are found in the Pacific and Indian oceans. Lophogastrids usually swim in deep, open waters down to depths of 3,280 feet (1,000 meters). Some species are found in waters as shallow as 164 feet (50 meters). Most lophogastrids are thought to be predators. They prey on free-floating animals called zooplankton. Only one species, Gna…
Cumaceans live around the world in oceans, seas, bays, and estuaries to the deepest trenches. Most species live in the ocean and brackish waters, but some are found in habitats where water is fresh for at least short periods of time. Many live on the bottom, just below the surface in soft mud or sand. They prefer habitats where there is some water current, but little wave action. One group li…
Most tanaids live in the ocean, but a few species prefer the brackish waters of estuaries where rivers meet the ocean. Most tanaids live at a wide variety of depths on the bottom of oceans and estuaries. Many species live at depths of more than 656 feet (200 meters); some are found below 29, 527 feet (9,000 meters). A few species live in the open ocean as free-floating plankton. Still others …
Mictaceans are found off the coasts of northeastern South America, southeastern Australia, Bermuda, the Bahamas, and the Cayman Islands. Mictaceans are found in underground sea caves or deep-sea habitats. No one is sure what mictaceans eat. The small body size and the shape of their mouthparts suggests that they scavenge dead plants and animals. The animals move both by walking and swimming. …
Spelaeogriphaceans are known only from small regions of South Africa, Brazil, and Western Australia. They are found in freshwater streams or pools in caves or in underground springs. Spelaeogriphaceans are thought to feed on bits of plants that are washed into the caves and underground springs. They use their mouthparts to sweep up small particles off rocks. Very little is known about these a…
Thermosbaenaceans are found in the North Atlantic Ocean, the Mediterranean Sea, and the southeastern Indian Ocean. Most thermosbaenaceans live in underground springs or in caves with brackish waters. Brackish water is less salty than seawater. Others live along the seashore or in underground caves filled with seawater. A few species live in hot springs at temperatures of 111 to 118°F (…
Isopods are found worldwide. Wood burrowing and feeding species living in oceans and estuaries can severely damage pilings, docks, and other underwater wooden structures. Pillbugs seldom cause any damage, but large numbers may eat seedlings and other garden and greenhouse plants. …
Amphipods are found worldwide. Most amphipods live on the ocean bottom and burrow in mud or debris. Many live in the open sea and are usually found on floating, jellylike animals, such as jellies and ctenophores. Others burrow into sandy beaches. About 1,200 species are found in fresh water, where they live among decaying leaves. About one hundred species live in moist habitats on land. Amphi…
Barnacles and their relatives are found worldwide in oceans and estuaries (EHS-chew-AIR-eez), where rivers meet the sea. Most barnacles eat algae (AL-jee), bacteria, tiny animals, and bits of other organisms floating in the surrounding water. Some stalked species prey on larger floating animals by capturing them with a single limb, or cirrus (SIH-ruhs). Parasitic thecostracans eat the tissues…
Very little is know about the distribution of these animals because of their small size. They are currently known to live in the North and South Pacific, North and South Atlantic, Arctic, and Antarctic oceans. Tantulocaridans spend most of their lives attached to other marine crustaceans living on the ocean floor. Their hosts include cumaceans, tanaids, isopods, amphipods, copepods, and ostra…
Fish lice are found in freshwater habitats on all continents. Fish lice parasitize freshwater fishes. A few species attack fish living along the coast or in estuaries, but they are never found out in the open sea. They are sometimes found on amphibians. Fish lice eat the skin and blood of their host. Fish lice are important pests in fish culture facilities. They usually occur in freshwater fa…
Mystacocarids are found along the coasts of the eastern and western Atlantic, southern South America, western Australia, and the Mediterranean Sea. Mystacocarids live in the spaces between the grains of sand found along coastal beaches. Mystacocarids probably eat algae (AL-jee) and bacteria living on the surfaces of sand grains. Mystacocarids use their antennae, mandibles, and slender bodies …
Copepods are found on every continent, including Antarctica. They also live in all of the world's oceans and seas. As a group, copepods eat a wide variety of foods. Some species grab tiny organisms, or bits of their tissues, floating in the water. Others are specialists and will eat only tiny algae (AL-jee). Species living on the bottom usually scavenge dead organisms, but some prey on…
Mussel shrimp are found in all oceans and on all continents. Most species live on the bottom, or near bottom. Some attach themselves to other organisms living on or near the bottom, including other species of crustaceans. One species lives in the gills of fish. Some live in open water, while others are found in very wet moss and leaf litter on land. Some ocean-dwelling species live at depths …
Tongue worms are found on all continents, but most species are found in the warmer tropics and subtropics. Adult tongue worms live in respiratory systems of vertebrates (birds, reptiles, and mammals). The larvae (LAR-vee) of tongue worms develop in the tissues and organs of hosts different from those of the adults. Larval hosts include arthropods, birds, reptiles, and mammals. Both the adults…
Aplacophorans are found in all oceans. They are found at depths ranging from 16 to 17,390 feet (5 to 5,300 meters). One group of aplocophorans lives on hydroids, corals, or on the ocean bottom. The other group burrows into the ocean bottom and lives in their tunnels upside down. Very little is known about the behavior of aplacophorans. Aplocophorans are either male, female, or hermaphrodites.…
They are found in the South Atlantic Ocean, Gulf of Aden, and several places in the eastern Pacific Ocean. Monoplacophorans live on deep-sea bottoms at depths between 624 to 22,980 feet (190 to 7,000 meters). They are found attached to rocks and solid objects. Monoplacophorans feed on bits of plants, animals, and other organisms. Nothing is known about their behavior. Both males and females a…
Chitons are found along seashores worldwide but are most common in cooler waters. Chitons live on hard surfaces, especially rocks. They are found from the seashore to depths of more than 13,123 feet (4,000 meters). Chitons eat many kinds of algae (AL-jee). Placiphorella velata preys on worms and small crustaceans. Native Americans living along the Pacific Coast of North America used to eat th…
Gastropods are found on all continents and in all oceans. Gastropods live in a wide variety of habitats in the ocean, on land, and in bodies of fresh water. Gastropods eat many kinds of foods. Some species filter out bits of plants, animals, and other organisms floating in the water. Many scrape algae (AL-jee) or crustlike animals off rocks in tide pools and elsewhere on the ocean bottom. Oth…
Bivalves are found worldwide in freshwater and ocean habitats. All bivalves need fresh or sea water to breathe, reproduce, and feed. Ocean-dwelling species are found from the seashore to deep-sea habitats. However, the Australian Enigmonia lives on mangrove leaves or seawalls beyond high tide and gets its moisture from sea spray. Most species live on the bottom or burrow into mud and sand. Ot…
Tusk shells are found in cool and warm water oceans worldwide, from seashores to depths down to about 23,000 feet (7,000 meters). Tusk shells are found only in soft, muddy ocean bottoms where they burrow to search for food. Tusk shells eat microscopic organisms, especially foraminiferans (fo-re-mi-NIH-fer-ehns), single-celled organisms that have a nucleus. The nucleus is a structure that cont…
Cephalopods are found in all of the world's oceans. Cephalopods are found in tide pools, on sea bottoms, and swimming in open water. They live at depths of 16,400 feet (5,000 meters) or more. Most cephalopods prey on fishes, crustaceans, and mollusks, including other cephalopods. However, nautiluses and their relatives scavenge dead animals. No species of cephalopods are considered thr…
Phoronids are found in all oceans and seas, except the Antarctic Ocean. Phoronids eat algae (AL-jee), small animal larvae (LAR-vee), and other plankton floating in the water. Phoronids do not impact people or their activities. No species is considered threatened or endangered. …
Freshwater ectoprocts are found on every continent, including Antarctica. Marine species live in every ocean. Freshwater species are found in shallow, still waters. They attach themselves to the sides or undersides of rocks, wood, plants, and trash. Marine ectoprocts live in shallow waters near the coastline to deep-sea bottoms at depths of 26,900 feet (8,200 meters). They are also found on t…
Lampshells are found in all oceans. Lampshells live on the bottom of oceans with cold, moderate, or warm waters. They either attach themselves to hard objects or bury themselves in mud or sand. They are found along seashores to depths of 17,410 feet (5,300 meters). Lampshells eat bits of plants, animals, and other organisms floating in the water. The sticky tentacles collect food from water f…
