Marine Zoology Glossary

The vast, flat area of the deep ocean floor, typically between 3,000 and 6,000 meters depth, characterized by fine sediment and low biodiversity compared to other benthic habitats.

Keratinous plates that hang from the upper jaw of mysticete whales, used to filter small prey such as krill and small fish from large volumes of seawater.

Relating to the bottom of a body of water or the organisms that live on or in the seafloor substrate.

The production and emission of light by a living organism through a chemical reaction, typically involving luciferin and luciferase.

Non-target species unintentionally caught during commercial fishing operations, including marine mammals, sea turtles, seabirds, and juvenile fish.

Any member of the order Cetacea, the group of fully aquatic marine mammals that includes whales, dolphins, and porpoises.

The biological process by which organisms produce organic molecules using chemical energy from inorganic compounds such as hydrogen sulfide, rather than sunlight.

A pigment-containing cell in cephalopods and other marine animals that can expand or contract to rapidly change skin color and pattern for camouflage or communication.

A specialized stinging cell unique to cnidarians (jellyfish, corals, anemones) that contains a nematocyst used for prey capture and defense.

The loss of symbiotic zooxanthellae from coral tissue due to environmental stress (especially elevated temperatures), causing the coral to turn white and potentially die.

A biological sonar system used by toothed whales to navigate and detect prey by emitting sound pulses and interpreting the returning echoes.

A subclass of cartilaginous fishes including sharks, rays, and skates, characterized by cartilaginous skeletons, multiple gill slits, and dermal denticles.

The uppermost layer of the open ocean (0-200 m), also called the sunlit or photic zone, where sufficient light penetrates for photosynthesis.

Excessive nutrient enrichment of a water body, often from agricultural runoff, leading to algal blooms, oxygen depletion, and dead zones harmful to marine animals.

A feeding strategy in which animals strain food particles from water, used by organisms ranging from sponges and bivalves to baleen whales and whale sharks.

The deepest oceanic zone, found in trenches below 6,000 meters, characterized by extreme pressure, near-freezing temperatures, and total darkness.

A species that has a disproportionately large effect on its ecosystem relative to its abundance, whose removal causes significant changes in community structure.

Organisms that spend only part of their life cycle as plankton, typically as larval stages, before settling into benthic or nektonic adult forms.

Actively swimming marine organisms that can move independently of currents, including fishes, cephalopods, and marine mammals.

The active regulation of osmotic pressure in an organism's body fluids to maintain homeostasis of water and ion concentrations.

Microscopic photosynthetic organisms that drift in the sunlit zone of the ocean; they form the base of most marine food webs and produce roughly half of Earth's oxygen.

Organisms that drift with ocean currents, unable to swim against them. Includes phytoplankton (photosynthetic) and zooplankton (animal or heterotrophic).

A network of closely packed, counter-current blood vessels that functions as a heat exchanger, found in tunas, lamnid sharks, and some billfish to maintain elevated body temperatures.

The position an organism occupies in a food chain or food web, from primary producers (level 1) to apex predators (level 4-5).

Animal and heterotrophic components of the plankton community, ranging from single-celled protists to small crustaceans like copepods and krill.