Decurved : Curved downward.
Depressed : Flattened from top to bottom so that the animal is wider than high.
Dermal Ridge : A ridge of skin.
Dolphin : A relatively small cetacean with (usually) a curved dorsal fin; also used interchangably with 'porpoise' as a general term.
Dorsal : Pertaining to the back or upper surface of the body.
Dorsal Fin : The fin along the midline of the back.
Dorsal ridge : A hump or ridge which takes the place of a dorsal fin on some cetaceans.
Echolocation : A system used by cetaceans to navigate, orientate
and find food by way of sending out signals and interpreting the returning
Emarginate : Notched, but not deeply forked.
Extinct: To describe a species or population that is no longer living
Ecosystem: A biological community and environment functioning
as a whole.
Falcate : Strongly curved or lunate.
Fathom : A unit of measurement used to indicate water depth, and equal to 1.8m (6 feet).
Flippers : In cetaceans, the forelimbs.
Flipper-slapping : Raising a flipper out of the water and slapping it onto the surface.
Flukes : In cetaceans, the horizontally positioned tail fin, resembling the tail of a fish, but not as vertical.
Fluking : The act of raising the flukes into the air upon diving.
Forked : Shaped like a fork; cleft or sharply angled.
Fusiform : Spindle-shaped, tapering toward ends.