Jaw animals live in Greenland and between Africa and Australia 1,500 miles (2,400 kilometers) north of Antarctica. Jaw animals live in moss or sand at the bottom of cold running or still freshwater. Jaw animals eat bacteria, algae, and diatoms. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Diatoms (DYE-uh-tahms) are a type of algae that have…
Gnathostomulids live all over the world but mainly in the northern part of the Atlantic Ocean and the southern part of the Pacific Ocean. Gnathostomulids live on sheltered beaches, near sea grasses and mangroves, and between coral reefs. Gnathostomulids graze on bacteria and threads of fungus attached to sand grains. Gnathostomulids glide between sand grains. They contract when disturbed. Som…
Priapulans live all over the world. Priapulans live in sand and mud in all oceans at all depths. Larger priapulans live in colder waters. Small priapulans are most common in shallow tropical waters. Priapulans eat sea worms. Because they are considered living fossils, priapulans are important for research. Priapulans are not considered threatened or endangered. …
Girdle wearers live all over the world. Girdle wearers live in the sea at all depths. They are common around the North Pole and the South Pole, especially in the deep sea. Girdle wearers live in the spaces between sand grains or in mud. Girdle wearers eat algae and bacteria. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Scientists may be abl…
Wheel wearers live in the northeastern part of the Atlantic Ocean, including the Mediterranean Sea. Wheel wearers live only on bristles in the mouths of Norway lobsters. Wheel wearers eat particles of the lobster's prey, usually mollusks and crustaceans. Mollusks (MAH-lusks) are animals with a soft, unsegmented body that may or may not have a shell. Crustaceans (krus-TAY-shuns) ar…
Sea lilies and feather stars live in the western part of the Pacific Ocean and on both sides of the Atlantic Ocean. Most sea lilies live in deep water, and most feather stars live on coral reefs. Both animals usually live on hard surfaces. Sea lilies and feather stars eat plankton and waste. Plankton is microscopic plants and animals drifting in water. Sea lilies and feather stars have no kno…
Sea stars live in the Pacific, Atlantic, and Indian oceans, including the Antarctic regions. Sea stars live in the sea from the shore to the deepest ocean. They live in sea grass beds, under rock rubble, on coral reefs and rocky underwater cliffs, and in sand and mud. Sea stars eat anything that is too slow to escape, such as mollusks, crustaceans, sponges, worms, and even other sea stars and…
Sea daisies live near New Zealand and the Bahamas. Sea daisies live on sunken wood in water deeper than 3,280 feet (1,000 meters). Sea daisies eat bacteria, dissolved nutrients on sunken wood, waste, and possibly microscopic mollusks. Mollusks (MAH-lusks) are animals with a soft, unsegmented body that may or may not have a shell. Sea daisies have no known importance to people. Sea daisies are…
Brittle and basket stars live in all the oceans of the world. Some brittle and basket stars burrow into muddy or sandy sea bottoms. Others live on or among algae, sponges, and coral. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Some brittle and basket stars eat sea animals, alive or dead. Others eat particles from the bottom or from the ope…
Sea urchins and sand dollars live all over the world. Sea urchins live on wave-exposed rocks, in crevices within rocks, in rock pools, on coral reefs, in sandy lagoons, in sea grass beds, and in kelp forests. Sand dollars live in sand and coarse gravel. Some sea urchins eat only algae, sea grass, and seaweed. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stem…
Sea cucumbers live all over the world. Sea cucumbers live in all sea habitats, ranging from areas exposed at low tide to the bottom of the deepest part of the ocean. Some species live on wave-hammered reef crests and rocky shorelines. Many species live on hard bottoms. Others burrow in sand or mud. Some species swim miles above the sea floor. Sea cucumbers eat algae, plankton, bacteria, and w…
Arrow worms live in all the oceans of the world. Arrow worms live in every part of the ocean. Most drift in open water close to the surface. Bottom-dwelling species live attached to objects such as sea grass and rocks. Arrow worms eat plankton, including tiny crustaceans, fish larvae, and other arrow worms. Digestion is rapid. Scientists believe each arrow worm eats two to fifty prey animals …
Hemichordates live in all the oceans of the world. Adult acorn worms usually live in shallow water in burrows at the bottom, but sometimes they live in the sand inside shells, under rocks, in thick seaweed, or between root tangles. Colony-forming hemichordates usually live in deep water in the tubes they make from mucus. Hemichordates eat bacteria, microscopic algae, diatoms, and nutrients th…
Sea squirts live in all oceans and seas. Sea squirts live at all depths. Most live in shallow water. Some even survive on open shores under strong wave action. Some sea squirts live in ocean trenches as deep as 28,000 feet (8,400 meters). Most species of sea squirts live on rocks, shells, or algae (AL-jee), which are plantlike growths that live in water and have no true roots, stems, or leave…
Salps are tiny, drifting sea animals that have a clear cylindrical body with openings at each end. Between the openings is a basketlike structure covered by a sheet of mucus. The jelly-like body wall contains bands of muscle. Most salps are 0.2 to 8 inches (5 millimeters to 20 centimeters) long. Some colonies are many feet (meters) long. Salps live in warm and cool seas. Most salps live near …
Larvaceans live in ocean currents all over the world. Larvaceans live in open ocean and near the shore in surface waters and in middle depths. Larvaceans eat plant plankton that they filter from the water that passes through them. Plankton is microscopic plants and animals drifting in water. Larvaceans can clear an area of plant plankton, eating the food needed by sea animals that fishes eat.…
Sorberaceans live in all the oceans of the world but have not been found in the northernmost waters of the Arctic Ocean or the northern part of the Pacific Ocean. Sorberaceans live at the bottom of the deepest part of the ocean, although some have been found in shallower water. The deep bottom is almost always soft and covered by a thick layer of mud, on which sorberaceans live unattached. So…
Lancelets live in all the oceans of the world in warm and cool waters. Lancelets live in sandy bottoms near the shore. The larvae may drift over long distances before settling. Larvae (LAR-vee) are animals in an early stage that change form before becoming adults. Lancelets eat plant plankton and diatoms. Plankton is microscopic plants and animals drifting in water. Diatoms (DYE-uh-tahms) are…
Sponges live all over the world. Most sponges live in the sea, but a few species live in freshwater. Many sponges live on reefs. Most sponges need a firm surface on which to attach, such as rocks or the skeletons of dead sponges and coral. Other sponges live on sand or mud at the bottom of the deep sea. Freshwater sponges live in lakes and streams. Sponges eat tiny particles such as bacterial…
Scientists do not know whether placozoans are widely distributed around the world. These animals are so hidden that their diversity may be much greater than scientists realize. The placozoans that have been studied are samples cultured in laboratory aquariums near warm seas. Scientists do not know where placozoans live under natural conditions. They may live on the surface of underwater rocks…
Salinella has been found only in Argentina. Scientists do not know where Salinella lives under natural conditions. Salinella eats by ingesting small particles into its internal cavity. Undigested particles are carried to the anus by the movement of hairlike fibers. Salinella has no known importance to people. Salinella is not threatened or endangered. …
Rhombozoans live in the northern, eastern, and western parts of the Pacific Ocean; in the waters around New Zealand and Australia; in the Mediterranean Sea; in the northern, eastern, and western parts of the Atlantic Ocean; in the Gulf of Mexico; and in the Antarctic Ocean. In the wormlike form, rhombozoans live only in the kidneys of octopuses, cuttlefish, and sometimes squid. Rhombozoans ab…
Orthonectidans live in the coastal regions of the northwestern part of the Atlantic Ocean and the Mediterranean Sea, the northwestern part of the Pacific Ocean near Japan, and the northeastern part of the Pacific Ocean along the coast of the United States. Orthonectidans live in the tissues of sea-dwelling invertebrates, such as flatworms; segmented worms; mollusks (MAH-lusks), or animals wit…
Anemones and corals live in oceans all over the world. Anemones and corals live in the sea in areas that are exposed at low tide all the way to the deepest ocean. Solitary forms may be attached to a hard material or may burrow into soft bottom mud or sand. Colonies build a crust on hard surfaces or build massive skeletons. Reef-building corals usually live in clear, shallow, warm water, altho…
Hydroids live all over the world. Hydroids live in all water habitats, from sea caves to deep-sea trenches, from lakes and ponds to rocky coasts and between grains of sand. Hydroid polyps and medusae feed on almost all animals, from plankton, or microscopic plants and animals drifting in water, to fish. The medusae of hydroids prey on the eggs and larvae of fish that people need for food. Som…
Box jellies have a cube-shaped body, or bell, also called an umbrella. The mouth is inside the bell. Tentacles are attached to each of the four lower corners of the bell. Some box jellies have several tentacles attached to each corner, and others have only one tentacle at each corner. A structure near the base of the bell contains one balance organ and six eyes. Box jellies live in warm coast…
Jellyfish live in all the oceans of the world. Jellyfish medusae live in seawater from shore areas exposed at low tide to the very deep ocean. The polyps are attached to hard surfaces, such as rocks, shells, and plants, at various depths. Jellyfish eat plankton, which is microscopic plants and animals drifting in water; fish eggs and larvae (LAR-vee), or young animals that must change form be…
Comb jellies live in all of the oceans of the world. Most comb jellies live in open ocean. Some live at the bottom. Comb jellies eat animal plankton or microscopic animals drifting in water, other jellies, crustaceans, mollusks, and fish larvae. Crustaceans (krus-TAY-shuns) are water-dwelling animals that have jointed legs and a hard shell but no backbone. Mollusks (MAH-lusks) are animals wit…
Acoels live in all the oceans of the world. Acoels live in shallow coastal seawater. Some drift or swim in open water, and others live among sand grains on the sea bottom. A few species live on other invertebrates (in-VER-teh-brehts), or animals without a backbone. Some acoels live on Antarctic ice floes. Acoels eat algae, plankton, and waste material. Algae (AL-jee) are plantlike growths tha…
Turbellarians live all over the world. The regrowth abilities of turbellarians have been studied extensively by scientists who want to understand healing and cell regrowth in humans. Several species of turbellarians kill food animals such as oysters, and a few species cause disease in ornamental fishes used in aquariums. The World Conservation Union (IUCN) lists one species of turbellarians a…
Flukes live all over the world. The habitat of a fluke is the same as that of its host and can change as the fluke goes from host to host. Flukes cannot live without nourishment from a host organism. In some species the larvae (LAR-vee), or animals in an early stage that change form before becoming adults, do not eat. Adult flukes eat blood cells, mucus, and body cells. Flukes pose a health t…
Monogeneans live all over the world. Many monogeneans live on or in specific hosts, mainly the skin of freshwater and saltwater fishes. Some species live in the bladders of frogs and toads and the bladders or mouths of freshwater turtles. One species lives beneath the eyelids of a hippopotamus. Another lives on the skin of squids. Most monogeneans feed on the skin of their hosts. Some eat blo…
Tapeworms live all over the world. Tapeworms eat by absorbing nutrients from their hosts' intestines. Tapeworms are not considered threatened or endangered. …
Anoplans and enoplans live all over the world. Most anoplans and enoplans live in the sea near shore— anoplans on soft bottoms and enoplans among algae. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Some species live in deep, open water. A few species live in freshwater or on land. The land-dwelling species usually live on tropical is…
Rotifers live all over the world. Most rotifers live in freshwater in sand or mud at the bottom, in plants, or in open water. Several species live in saltwater, usually among plants but sometimes between grains of sand on beaches. Rotifers eat algae and other protists, bacteria, and even other rotifers. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or …
Gastrotrichs live all over the world. All gastrotrichs live in water. About one-half of all species live in the sea between sand grains on beaches and the continental shelf. Some species live in the deep sea. Freshwater gastrotrichs live on submerged or floating plants, drift in open water, or live between grains of sand. Gastrotrichs eat algae, other protists, and bacteria. Algae (AL-jee) ar…
Kinorhynchs live all over the world. Kinorhynchs live in all seas from polar to tropical and at all depths. Most live in mud or mud mixed with sand. Kinorhynchs eat diatoms, waste material, and bacteria. Diatoms (DYE-uh-tahms) are a type of algae that have a shell. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Kinorhynchs have no known impor…
Roundworms live all over the world. Roundworms live in water and soil everywhere except the desert. A few species are parasites of plants and animals. Parasites (PAIR-uh-sites) are animals or plants that live on or in other animals or plants, or hosts, without helping them and usually harming them. Most roundworms eat bacteria, fungi, and tiny growths in the soil. The parasite species feed on…
Secernenteans live all over the world. Most secernenteans live in plant and animal hosts in all types of land habitats. They are rarely found in the sea or in freshwater habitats. Species that are not parasites often live in the soil. Secernenteans feed on blood, body fluid, intestinal contents, and mucus in their hosts. They eat bacteria, fungi, and other growths in the soil. Secernenteans a…
Hair worms live all over the world except Antarctica. One type of hair worm lives in sea animals such as crabs and shrimp. The other type lives in insects such as crickets, grasshoppers, and beetles. The worms that live in insects usually are found in slow-moving freshwater streams or ponds. In streams the worms are either attached to plants hanging over the banks or live between rocks on the…
Thorny-headed worms live all over the world. Adult thorny-headed worms live in the intestines of mammals, birds, fishes, amphibians, and reptiles. Larvae live in crustaceans and insects. Thorny-headed worms absorb nutrients from their hosts' intestines. Thorny-headed worms are not considered threatened or endangered. …
Entoprocts are tiny bottom-dwelling animals that have a crown of tentacles and a thin stalk. Both the mouth and anus (AY-nuhs) open inside the crown. Some entoprocts live in colonies and are attached to one another by a branch at the base of their stalks. Entoprocts live all over the world. Most entoprocts live at the bottom of warm, moderate, and cold seas from the shore to deep water. One s…
