ambergris--waxy material found in the intestinal tract of sperm whales presumably to help with the digestive passage of squids' beaks. The largest hunk of ambergris found was 926 pounds. It is used as a fixative for perfumes and, in some countries, as an aphrodisiac.

ammonia--enables giant squid to maintain neutral buoyancy without expending a lot of energy. Ammonium ions (charged particles produced by ammonia in water) are lighter than sea water.

arms--the eight sucker-lined or hook-lined appendages of squids and octopuses (not tentacles!!)

bathymetric chart--a drawing that shows the depth of formations on the ocean floor

bioluminescence--production of light by living organisms

cephalopod--a class of animals in the phylum Mollusca. These animals are invertebrates with two basic body parts, a head and a mantle. A cephalopod has a well-developed brain, and a circulatory system with three hearts, veins, and arteries. Usually cephalopods have ink sacs and no external shell. Not only do they live in the sea and use jet propulsion in order to move, they can usually change skin color and texture.

chitin--hard, flexible, fingernail-like substance forming the outer covering of insects and crustaceans

chromatophore--elastic sac containing pigment in the skin of cephalopods

continental shelf--gently sloping underwater land that extends from the coast to about 200 meters in depth.

continental slope--steeply sloped underwater land that lies at the seaward border of the continental shelf and runs from a depth of about 200 meters to 3200 meters.

counterillumination--the lighting of the underside of an animal with bioluminescence which eliminates its silhouette through "downlighting"

dorsal--back or upper surface of an animal; the opposite of ventral

"down-lighting"--the light that comes down through the water from the sun, moon and stars

echolocation--the ability of animals to locate objects through the use of sound generated and received by the animal

funnel--short, hose-like organ that projects from the mantle of cephalopods and can be rotated in any direction. It is used for breathing, jetting, squirting ink, laying eggs, and expelling waste.

gladius--a feather-shaped internal blade that supports the mantle of squids and serves as a site for muscle attachment. It is made of a chitin-like substance similar to shrimp shells but harder. It is also called a pen.

guyot--seamount with a flat plateau on top

invertebrates--animals without backbones

luciferase--a pigment in bioluminescent animals such as fireflies or certain marine invertebrates, that produces an almost heatless, bluish-green light

luminescence--the production of light by animals or plants

mantle--main part of the body of a squid, like the trunk of a human. It contains most of the organ systems: reproductive, digestive, respiratory, circulatory (gills and heart), as well as the ink sac.

mid-ocean ridge--mountain range that runs along the ocean bottom formed at the boundaries of oceanic plates. The base is in very deep water and the top may break through the ocean surface to form oceanic islands, such as the Western Azores.

Mollusca (mollusks)--a large group of invertebrates, found primarily in salt water, including clasm, oysters, and snails. Most mollusks have a hard, limy outer shell protecting a soft body, but some, as in the squid and octopus, lack this type of shell. Many have a muscular foot found ventrally.

neutral buoyancy--neither floating nor sinking at any "chosen" depth

nidamental glands--glands important in the laying of eggs of the squid. They produce a gelatinous matrix that holds the eggs.

photophore--light-producing organ.

pigment--a substance that produces a characteristic color in plant or animal tissue

prismatic--describes an object that refracts light and breaks it into component wavelengths, creating colors

profile--side view

pseudomorph--"false body"; ink squirted by a squid that takes the approximate shape of the squid and acts as a decoy

radula--ribbon of backward pointing teeth covering the tongue of most mollusks. The teeth are composed of a material similar to chitin.

seamount--underwater mountain with a round, pointed or irregular top

tentacles--two long appendages on squids but not found on octopuses. They are longer than the eight arms, often containing hooks and/or suckers on the ends (or clubs) and are used to catch prey.

teuthologist--a scientist who specializes in the study of cephalopods

trench--deep underwater canyon in the ocean floor; deepest part of the ocean

ventral--the belly or under surface of an animal; opposite of dorsal