Glossary

AFT: near or toward the rear of a boat.

AMPULLAE OF LORENZINI: bundles of sensory cells connected to nerve fibers in the head of a shark that allow it to detect electric fields.

ANTHROPOMORPHIZE: to use human characteristics to describe nonhuman things.

APEX PREDATOR: an animal at the top of the food chain.

THE BENDS: (also called decompression sickness) pain and other symptoms caused by leaving a compressed atmosphere too quickly. Bends can be fatal.

BIOLUMINESCENCE: light produced by living organisms.

BOW: the front of a boat.

BRACKISH: salty, dirty. Brackish water is often found where a river meets the sea.

BUOY: an anchored float used to mark a reef or channel, or to moor a boat.

CARNIVORE: a meat-eating animal.

CARTILAGE: a tough, elastic connective tissue. It is found in humans in various parts of the body, such as the ear, nose, and throat, and forms a shark's skeleton.

CAUDAL KEEL: the horizontal ridges along the tail fin of sharks and other fast-swimming fish.

CETACEAN: a marine mammal in the order (Cetacea) that includes whales, dolphins, and porpoises.

CHITIN: a horny substance that forms part of that hard outer layer of crustaceans and insects.

CHUM: chopped fish or other organic matter used as bait.

CLEAT: a T-shaped piece of metal or wood on a boat, to which ropes are attached.

CRUSTACEAN: one of a large group of aquatic animals with shells that includes lobsters, shrimp, and crabs.

DERMAL DENTICLES: tiny scalelike teeth that make up the skin of a shark.

DORSAL FIN: a fin on the back of a fish or marine mammal, such as the tall triangular one on a shark or a killer whale.

ELASMOBRANCH: a class of fish with a skeleton made of cartilage (not bone), including sharks, rays, and skates.

EMBOLUS: an air bubble or clot that has been carried through the bloodstream to block an artery.

FLANK: the side of the body, between the ribs and hip, on animals and humans.

FLOTSAM: floating wreckage of a ship or its cargo.

NICTITATING MEMBRANE: an inner eyelid that closes to protect the eye of birds, reptiles, and many sharks.

PECTORAL FIN: each of a pair of fins on either side just behind a fish's head.

PLANKTON: tiny plants and animals that serve as food for larger fish.

PORT: the left side of a boat (when you are facing forward).

PREDATION: obtaining food by killing and eating animals.

REEF: a chain of rocks or coral at or near the surface of the sea.

REGULATOR: a device that controls the pressure from a tank of compressed air, allowing a diver to breathe comfortably underwater.

SANDBAR: a ridge of sand built up by currents.

SCAVENGER: an animal that feeds on dead or decaying matter.

SHOAL: a sandbank or sandbar that makes the water shallow.

STARBOARD: the right side of a boat (when you are facing forward).

STERN: the rear end of a boat.

SYMBIOSIS: the close association of two different organisms living together in a mutually beneficial relationship.

TOURNIQUET: a device, such as a tight bandage, used to stop bleeding.

WET SUIT: a tight-fitting rubber suit worn for warmth in water sports or diving.