CHORDATES

LANCELET
(Branchiostoma)

A lancelot looks like a small, transparent fish, with an extremely narrow body. It lurks on the seabed, half-buried in sand, using tentacles to pump water into its mouth. Once the water is inside, sievelike slits filter out small particles of food, and the waste water is pumped away. Lancelets do not have eyes or jaws, and they have only the beginnings of a brain. However, many of the features they do have, such as muscles arranged in blocks, also appear in fish and other vertebrates.

SEA SQUIRT
(Didemnum molle)

Adult sea squirts live fastened to solid objects and feed by pumping water through their baglike body. Young sea squirts, however, look completely different. They have a tadpole-shaped body, reinforced by a notochord, and swim in open water. They settle on rocks to turn into adults, and their notochord disappears.

JAWLESS FISH

ATLANTIC HAGFISH
(Myxine glutinosa)

These deep-sea scavengers feed on dead or dying fish. They find their food using their keen sense of smell, and they often slither right inside their prey. A hagfish does not have jaws, but it has small teeth that is uses to eat its prey from the inside. As a defense, it secretes an obnoxious, slimy substance. To remove it, the hagfish ties a knot in its body, which it slips down to its tail. Hagfish lay elongated eggs, and their young look like small adults when they hatch.

SEA LAMPREY
(Petromyzon marinus)

Adult sea lampreys are parasites that feed on the blood of other fish. They have sharp teeth for clamping onto their prey. Lampreys can cling on for weeks, taking so much blood that the victim often dies. Like all lampreys, the sea lamprey breeds in fresh water. Its young, called ammocoete larvae, are blind and toothless. They spend up to six years filtering food from the water before they develop into adults and travel downriver to the sea.

BROOK LAMPREY
(Lampetra planeri)

Unlike sea lampreys, brook lampreys spend all of their lives in fresh water. They are not a threat to other fish because the adults do not feed. The female lays her eggs in gravel or sand. These eggs produce filter-feeding larvae that take about five years to grow into adults. After spawning the adults die.

ECHINODERMS

EDIBLE SEA URCHIN
(Echinus esculentus)

Sea urchins have round, spine-covered bodies. Their mouths, on ther undersides of their bodies, have five pointed teeth for scraping algae from rocks. Their spines protect them from predators. The edible sea urchin has sharp spines that snap off and stick in skin. Others have blunt spines that they use to jam themselves safely into rocky crevices. When sea urchins die, the spines fall off, leaving skeletons called tests.

HEART URCHIN OR SEA POTATO
(Spatangus)

Instead of creeping over rocks, heart urchins burrow into seabed sand. They plow slowly beneath the surface, pointed end first, using their tube feet to collect particles of food. On their upper sides, heart urchins have long tube feet that they use to dig tunnels up to the surface of the sand. They use these tunnels as water vents, which enables them to breathe.

SAND DOLLAR
(Dendraster)

These sea urchins have flat, circular bodies and short spines. They have a star-shaped pattern of tiny holes on their upper sides, which connect to five rows of tube feet. Sand dollars live on the seabed, where they crowd together near the shore. They produce a sticky mucus that traps particles of food floating in the water.

SEA CUCUMBER
(Stichopus)

These sausage-shaped animals creep across the seabed, using a set of frilly tentacles to collect food. Unlike other echinoderms, their mouths are at one end of their bodies. Sea cucumbers are protected by tough skin and a skeleton of chalky spikes. If an enemy comes too close, a threatened sea cucumber has another defense-it turns its anus toward its attacker and ejects a tangle of sticky thread.

NORTHERN SEA STAR
(Asterias rubens)

There are about 1,500 species of sea stars, also called starfish, living in oceans all over the world. Most of them have five arms, but some have as many as 50. Some sea stars have such short arms that they look like five-sided cushions, and most can replace any arms that are broken or bitten off. The northern sea star lives in shallow water, eating mussels and other bivalve mollusks. It creeps over its victims and pries open their shells with its tube feet. Once a small gap has opened up, the sea star slips its stomach inside its prey's shell and digests the soft body.

CROWN-OF-THORNS STARFISH
(Acanthaster planci)

This tropical starfish has up to 23 arms covered with poisonous spines. It feeds on reef-building corals, eating their soft bodies and leaving the skeletons behind. In recent decades, plagues of these starfish have attacked the Great Barrier Reef off the northeastern coast of Australia, raising fears for the reef's survival. Biologists now think that these plagues are natural events that have occurred many times before. After each onslaught, the starfish die off, and the reefs slowly recover.

COMMON BRITTLE STAR
(Ophiothrix fragilis)

Brittle stars look like starfish, but the are much more slender and faster on the move. Thier arms, joined to a disk-shaped body, are flexible but break off easily if touched. The common brittle star lives near the shore, but other species spend their lives in deep water. They eat dead remains or small particles of food that drift down from the water above.

**All Facts and Information contained in this website can be found in the following reference materials: The Kingfisher Illustrated Animal Encyclopedia and The Complete Book of Animals from The American Education Publishers

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