Abyssal zone: The ocean depth range below the 4o C isotherm extending from a depth of 2000 to 3000 meters down to approximately 6000 meters
Adipose fin: a fin without a bone or cartilage, located behind the dorsal fin
Anadromous: Species that live their adult lives in the ocean but move into freshwater streams to reproduce or spawn (e.g., salmon).
Antarctic Convergence: a line encircling Antarctica where cold, northward-flowing Antarctic waters sink beneath the relatively warmer waters of the sub-Antarctic. The convergence is a dynamic boundary, meaning it's precise location may shift, but is generally located between 48º S and 61º S latitude
Arctic waters: Marine and estuarine waters north of 60° N. latitude.
Arribada: the Spanish word for arrival; massive synchronized nesting within the genus Lepidochelys
Baleen: Long, flat plates made of fingernail-like material called keratin that hang from a baleen whale's mouth in place of teeth.
Barbel: A fleshy sensory appendage, often arising from the head or chin area of a fish (e.g., catfish "whiskers").
Benthic: anything associated with or occuring on the bottom of a body of water
Benthopelagic: occurring on the bottom or midwaters of a body of water
Blackfish: a non-taxonomic grouping of predominantly small, dark cetaceans (e.g., pilot whales)
Bow riding: swimming near the front part of a ship
Brackish: Pertaining to waters with a salt concentration between that of pure ocean water and freshwater. Waters of many bays that are almost totally enclosed by land are brackish.
Breach: to leap out of water
Bycatch: Animals caught by fishing that were not the intended target of the fishing activity. Such unwanted catch is often wasted.
Caudal Peduncle: the portion of a cetacean's body between the dorsal fin and the fluke (tail). See also: tailstock
Diatoms: minute planktonic unicellular or colonial algae
Dimorphism (sexual): males and females appear visually different
Dorsal: relating to or situated near or on the back
Elasmobranch: Elasmobranchii is the subclass of cartilaginous (with skeleton made of cartilage rather than bone) fishes (class chondrichthyes) that includes skates, rays and sharks. Elasmobranchs have an upper jaw that is not fused to the braincase and separate slitted gill openings.
Endemic: Native to a certain area, usually a relatively small area.
Endothermic: Animals that generate body heat above ambient temperatures through various physiological and anatomical specializations.
Epipelagic: waters from the surface to depths generally not exceeding around 650 feet (200 m).
Estuary: A semi-encolsed body of water having connections to the ocean at the downstream end and freshwater streams at the upstream end. Water in estuaries thus tends to be at an intermediate and variable salinity and temperature.
Euryhaline: Tolerant to a wide-range of salinities.
Falcate: hooked, curved, sickel-shaped; often referring to the shape of a dorsal fin.
Fall Line: A line connecting the waterfalls of nearly parallel rivers that marks a drop in land level.
Fecundity: the potential reproductive capacity of an organism or population, measured by the number of gametes (eggs)
Flipper Slapping: Flipper or fluke slapping is when a cetacean slaps the water with its flipper or fluke. This action sometimes creates a very loud sound that has been described as sounding like a gun shot.
Fluke: the tail of a whale
Fluking: When the fluke (tail) is raised vertically out of the water
Foot: in gastropod mollusks, such as black abalone, the foot is a muscular appendage used for movement and adhering to substrates
Fork Length: measurement from the tip of the snout to the fork of the tail.
Keel: a deepening or thickening of the body, particularly near the tail of some cetaceans.
Lobtailing: when a cetacean lifts its fluke (tail) out of the water and slaps it on the surface of the water
Lanugo: the thick fur of a pinniped shed after birth
Logging: floating motionless
Mantle: as in mollusks, such as the black abalone, the mantle is a thin layer of tissue that covers most of the organs and produces the shell
Melon: the often bulging, fatty forehead of a toothed cetacean
Mesopelagic zone: ocean depths extending from 200 m (650 ft) down to around 1000 m (3280 ft) below sea level
Molt: the process of shedding hair, skin, or an outer layer periodically to be later replaced by new growth
Morbillivirus: A highly contagious and lethal genus of virus (Family Paramyxoviridae) that has been responsible for more significant marine mammal die-offs due to infectious disease than any other pathogen to date.
Mottling: spots or blotches of different color or shades of color, as if stained
Myctophids: small, deep sea fish found worldwide. They are also known as lanternfishes, named for their ability to emit light
Natal: Pertaining to birth, usually in the context of animals that return to their place of birth to spawn or give birth themselves (e.g., many salmon).
Neritic Zone: nearshore area
Panmictic: Random mating of individuals within a population, the breeding individuals showing no tendency to choose partners with particular traits.
Parts: Hard parts are any bone, tooth, baleen, treated pelt, or other part of a marine mammal that are relatively solid or durable. Soft parts are any marine mammal part that is not a hard part (e.g. blood, muscle, blubber, skin, tissue-derived parts such as cell lines and DNA), excluding urine or fecal material.
Pectoral flippers: forelimbs of whales and dolphins that are used for stability and steering; they are generally flattened and paddle-like.
Pelagic: Pertaining to the part of the open sea or ocean comprising the water column, i.e., all of the sea other than that near the coast or the sea floor.
Pitch-pole: to turn end over end
Plankton: Passively drifting or weakly swimming organisms that occur in swarms near the surface of open water
Polygamy: the tendency for one male to mate with two or more females
Porpoising: when an animal moves in and out of the water in a series of high speed leaps, much like a porpoise. Dolphins, whales, seals, and even penguins have been observed porpoising.
Pupping Season: The time of year that seals give birth.
Rooster Tail: spray of water created as a porpoise or dolphin surfaces at high speed, especially characteristic of the Dall's porpoise
Rostrum: Any beaklike prolongation, especially of the head of an animal. In various marine mammals, the rostrum is commonly referred to as the beak or snout.
Scutes: Horny plates or thorny scales, as on the shell of a sea turtle or body of a sturgeon, respectively.
Sill: submerged ridge or vertical wall of relatively shallow depth separating two bodies of water
Smoltification: a complex developmental transformation, involving physiological, biochemical, morphological, and behavioral changes, that allows young salmon (parr) to transition from living in freshwater to living in saltwater
Spermaceti Organ: an organ inside a sperm whale's head that, historically, whalers believed produced sperm, but actually contains high quality oil.
Spyhopping: When whales and dolphins raise their heads vertically out of the water.
Stock: As defined by the MMPA, the term stock means a group of marine mammals of the same species or smaller taxa in a common spatial arrangement, that interbreed when mature.
Tailstock: the portion of a cetacean's body between the dorsal fin and the fluke (tail). See also: caudal peduncle
Thoracic: relating to the thorax, the part of a mammalian body between the neck and the abdomen
Threatened: Defined under the ESA as "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range."
Vomer: bone in the roof of the mouth, may have teeth in some species, such as the Pacific eulcahon
Whelping: giving birth