This glossary contains definitions of obscure or scientific terms used here as they pertain to marine life.
An adaptation is a physical or behavioral characteristic that has developed to allow an organism to better survive in its environment.
Baleen is a strong, yet flexible material made out of keratin, a protein that is the same material that makes up our hair and fingernails.
Blubber is a fat layer underneath an animal’s skin. Blubber is composed of fat-filled cells and functions both to insulate and to store food reserves. Animals that have blubber include whales, seals and walruses.
Bycatch describes animals caught unintentionally by fishing gear, including non-target species and undersized fish. Many fishermen seek to catch a "target" species. When fishermen catch something that they didn't intend to, such as a different fish species, a whale or dolphin, sea turtle or seabird, that is called bycatch.
Byssal, or byssus threads are strong, silky fibers made from proteins that are used by mussels to attach to rocks, pilings, or other substrates.
A carapace is a shell on an animal’s back, or part of its back.
Cartilage is a tough, flexible tissue, which is softer than bone. In humans, cartilage forms a temporary skeleton in the fetus and infant, and is later replaced by a bone skeleton.
"Cetacean" is the word for all mammals in the order Cetacea, which includes whales, dolphins and porpoises.
Chordata is the phylum that includes all the animals that have a notochord, or nerve cord, at some stage of their development. Animals in this phylum are known as chordates. The most well-known chordates are the vertebrates - animals that have a spine.
The Kingdom Chromista contains plant-like organisms that possess chlorophyll a and c and other pigments that give them their yellow-brown color (fucoxanthin). Examples of chromists: brown algae (e.g., kelp), water molds, diatoms.
Cnidaria is a classification phylum that includes corals, sea anemones, sea jellies (jellyfish), sea pens, and hydras. Cnidarians are radially symmetrical and have tentacles with stinging structures called nematocysts.
Corals are animals in the Phylum Cnidaria. Cnidarians also include sea fans, sea pansies and anemones. Corals are in the class anthozoa, and can be divided further into the stony corals - Order Scleractinia, the builders of coral reefs, and soft corals - Order Alcyonacea, which are soft or leathery and include species such as bubblegum corals and mushroom corals.
Countershading is a type of coloration commonly found in animals, and means that the animal's back (dorsal side) is dark while its underside (ventral side) is light.
Dermal denticles (placoid scales) are tough scales that cover the skin of elasmobranchs (sharks and rays). Even though denticles are similar to scales, they are really modified teeth and are covered with a hard enamel.
Toothed whales, such as dolphins, porpoises and orcas, make high-frequency sounds that bounce off of whatever is in front of them, including prey, terrain and obstacles. They receive these sounds and can sense the size, shape, density, distance and even the texture of the object in front of them. This is called echolocation.
Definition of ectothermic. An ectothermic animal is one who cannot regulate its own body temperature, so its body temperature fluctuates according to its surroundings.
The term elasmobranch refers to the sharks, rays and skates, which are in the subclass Elasmobranchii and class Chondrichthyes. The Condrichthyes class includes only one other subclass, the Holocephali (chimaeras), which are unusual fish found in deep water.
Cartilaginous fishes like sharks and rays have an electro-receptor system, that is a finely-tuned sensitivity to electrical fields. Sharks and rays have tiny pores on their skin that attach to long tubes containing a jelly-like fluid with a sensory nerve cell at the end, called ampullae of Lorenzini.
Definition of endothermic. Endothermic animals are those that must generate their own heat to maintain their body temperature. These animals are commonly referred to as warm-blooded.
Evolution is the process by which species change over a long period of time
Herbivorous organisms are those that feed on plants. The word herbivorous comes from the Latin word herba, meaning grass, and vorus, meaning "feeding on.
A holdfast is the root-like structure at the base of an algae (seaweed) that fastens the algae to a hard substrate. Holdfasts are prominent in brown algaes and seaweeds such as kelp.
A hybrid is an offspring of parents that are two different species or subspecies.
An ichthyologist is a scientist who studies fish.
Ichthyology is the branch of zoology that involves the study of fish.
The term lunate refers to "crescent-shaped." In a marine biology sense, it can refer to the shape of a fish's tail, which can be said to be lunate (the upper and lower "lobes" of the tail fin are about equal in size) or non-lunate (one lobe is longer than the other.)
Definition of mammal. Characteristics of mammals and examples of mammals.
Marine debris is something in the marine environment (such as in the ocean or on the beach) that doesn't naturally occur there. Learn the definition of marine debris, examples of marine debris, and threats of marine debris and how you can prevent them.
Marine Protected Areas (MPAs) are used to protect natural and/or cultural areas from human impacts and to help sustain important habitats. One MPA may be much different from another in terms of restrictions and management approaches.
The maximum sustainable yield (MSY) is a term often used in fisheries management.
Migration in marine animals involves the movement from one area to another, and back again. This movement is usually related to food availability or reproduction. Learn about migration and marine animals who migrate.
Mutation is an accidental change in an organism’s gene or chromosome that results in a new trait.
A necropsy is a dissection of the dead body of an animal to determine the cause of death. Necropsies can help us learn more about the biology of an animal, how it is affected by disease or how human interactions may impact animals.
Nekton is the term that refers to the "swimmers," the animals in the ocean that can move independently of ocean currents, by swimming or using another form of locomotion. This means that, unlike plankton, they are capable of determining their location in the ocean.
Overfishing is, simply put, when so many fish are caught that the population can't reproduce enough to replace them. Overfishing can lead to depletion of or extinction of fish populations.
Ovoviviparous animals produce eggs, but instead of laying the eggs, the eggs develop within the mother's body.
A pheromone is a chemical produced by some animals that cause specific reactions in other animals.
The term phylum is one of seven major categories that are used to classify organisms. In order of broad to specific, these seven categories are: Kingdom, Phylum, Class, Order, Family, Genus, and Species. This classification system was developed by Carolus Linnaeus in the 18th century
Placoid scales (dermal denticles) are tough scales that cover the skin of elasmobranchs (sharks and rays). Even though placoid scales are similar to the scales of bony fish, they are really modified teeth and are covered with a hard enamel.
"Plankton" is the term that generally refers to the "floaters" - the organisms in the ocean that drift with the currents. This includes the algae, zooplankton ("animal plankton"), phytoplankton (plankton that are capable of photosynthesis) and bacteria.
Pneumatocysts, or air bladders, are gas-filled sacs in an algae that that float the algae's blades up toward the water's surface, providing greater access to sunlight for photosynthesis.
A body part that is prehensile is one that is adapted for grasping or seizing.
Protists are organisms in the kingdom Protista. These organisms are eukaryotes, meaning they are made up of single or multiple cells which all contain a nucleus enclosed by a membrane.
The radula is a special structure used by many molluscs to scrape food off rocks or create depressions in rocks that the mollusc uses for habitat.
A rorqual is a baleen whale with a dorsal fin and throat pleats, or grooves, that extend from the whale’s lower lip down past its flippers.
The term rostrum is defined as an organism’s beak or a beak-like part. In cetaceans...
A seamount is an underwater mountain. The base of the seamount is on the seafloor and its summit doesn't reach the water surface. There are thousands of seamounts located throughout the world's oceans.
Definition of the word sessile, as used in a marine life context.
Sirenians are mammals in the Order Sirenia, which includes manatees and dugongs. These animals are herbivorous, and have two forelimbs and a flattened tail.
Spiracles are found in bottom-dwelling sharks and rays. They are a pair of openings just behind the animal's eyes that allow the it to draw oxygenated water in from above.
A subspecies describes a group of related organisms that can interbreed and are geographically distinct from others in their species.
Turtle excluder devices (TEDs) were created to protect sea turtles from getting caught in shrimp nets. The TED is attached to a shrimp trawling net and is a grid of metal bars that has an opening at the top or bottom, creating a hatch that allows sea turtles and larger fish to escape. Small animals such as shrimp go between the bars and are caught in the end of the trawl.
Zoology is the scientific study of animals.
