NOAA Coral Reef Information System - Glossary of Terminology Coral Reef Information System Home Data & Publications Regional Portals CRCP Activities Glossary HOME> GLOSSARY HOME> GLOSSARY OF TERMINOLOGY AND ACRONYMS/ABBREVIATIONS Glossary of Terminology A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | abalone a univalve mollusk (class Gastropoda) of the genus Haliotis. Abalones are harvested commercially for food consumption. The shell is lined with mother- of-pearl and used for commercial (ornamental) purposes Sea otters are in direct competition with humans for abalone. (Photo: Ron McPeak) abatement reducing the degree or intensity of, or eliminating abaxial away from, or distant from the axis abbreviate shortened abdomen in higher animals, the portion of the body that contains the intestines and other http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology viscera other than the lungs and heart; in arthropods, the rearmost segment of the body, which contains part of the digestive tract and all the reproductive organs The ventral surface of the abdomen of an American lobster. Prominent are the swimmerettes, uropods, and telson. abdominal fin a term used to describe the location of the pelvic (ventral) fins when they are inserted far behind pectorals. This is the more primitive condition. More recently evolved conditions have the pelvic fins in the thoracic or jugular positions. A salmon, for example, has its pelvic fins in the abdominal position. An angelfish has the pelvic fins in the thoracic position, and blennies have the pelvic fins in the jugular position, anterior to the pelvic girdle abductor a type of muscle whose function is to move an appendage or body part away from the body of an animal. Abductors work antagonistically with adductors abiogenic refers to things not involved with or produced by living organisms abiotic refers to nonliving objects, substances or processes ablation the experimental removal or killing of some part of an organism abnormal not normal; contrary to the usual structure, position, behavior or rule aboral situated opposite to, or away from the mouth; normally used to describe radially symmetrical animals, such as starfishes, sea urchins, and jellyfishes Spines protect the aboral surface of http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology a sea urchin. (Photo: NOAA) abraded worn or frayed abranchiate lacking gills abrasion the mechanical process of gradually breaking down a hard layer absolute tautonymy in taxonomy, the identical spelling of a generic-group name and one of its included specific-group names, such as the fish, Badis badis, or the western lowland gorilla, Gorilla gorilla gorilla absolute zero the temperature at which all motion will cease (0 degrees Kelvin or -273.15 degrees C) absorption the biological process that follows digestion, by which the products of digestion are transferred into the organism's internal environment, enabling them to reach the cells absorptive feeder an animal, such as a parasitic tapeworm, that absorbs digested food products through the body wall A parasitic tapeworm is an absorptive feeder. The narrowest point is the "head" or scolex which attaches the parasite to the intestinal lining by means of suckers and/or little hooks. Predigested nutrients are absorbed through the wall of each of the progressively larger segments. These animals have no digestive canal. (Photo: HHS/Centers for Disease Control and Prevention) http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology abundance the number or amount of something, e.g., the number of organisms per unit of habitat space or number of individuals in a stock or a population Acanthaster the Crown-of-Thorns starfish genus. Acanthaster planci is a voracious Indo- Pacific predator of corals Crown-of-Thorns starfish (Acanthaster sp.), a voracious predator of corals. acantho- a prefix meaning "with spines" The phylum Acanthocephala contains about 1,000 species of spiny-headed worms. All are endoparasites in the intestinal tract of vertebrates, especially fishes. (Image: Dr. Rick Gillis, Biol. Dept., Univ. of Wisconsin) acanthocaulus a juvenile coral of some species that is attached to the substrate either directly or on a stalk acanthoid thorny, spiny, sharp acanthotrich (acanthotrichium) in fishes, a spiny dorsal or anal fin ray acaudal lacking a tail http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology acaudal lacking a tail accepted name in taxonomy, a name adopted by an author as the correct name for a taxon accessory pigment a photosynthetic pigment which absorbs light and transfers energy to chlorophylls during photosynthesis accessory respiratory organ in fishes, a superficial or internal organ which complements the gills in respiration when the fish is in poorly oxygenated water or in air acclimation (acclimatization) a change that occurs in an organism to allow it to tolerate a new environment accretion growth by virtue of an increase in intercellular material accuracy the closeness by which a set of measurements approaches the true value acellular describes the construction of an organism or tissue that is a mass of protoplasm which is not divided into cells, e.g., some structural parts of slime molds and fungi aciculate needle-like or having needle-like parts acid a substance that increases the hydrogen ion concentration in a solution acid rain the precipitation of sulfuric acid and other acids as rain. The acids form when sulfur dioxide and nitrogen oxides released during the combustion of fossil fuels combine with water and oxygen in the atmosphere acidic http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology having a pH of less than 7 acidophilia an abnormal increase in the number of eosinophils in the blood which is characteristic of allergic states and various parasitic infections; also called "eosinophilia" acidophilous having an affinity for or thriving in acidic conditions, e.g., in a bog or marsh acoelomate an animal that does not have a true coelom or body cavity, i.e., a body cavity between the outer wall and the gut and lined with mesoderm. Acoelomate phyla include the flatworms (Platyhelminthes), ribbonworms (Nemertea), and jaw worms (Gnathostomulida) Acoelomate flatworms such as this Pseudoceros sp. lack a coelom (body cavity). (Photo: Adam Petrusek) acolonial coral a solitary coral that does not form a colony acontium a thread-like part of a coral polyp's or anemone's digestive system and employed as defensive or aggressive structures when extruded acoustic scattering the irregular reflection, refraction, or diffraction of a sound in many directions acoustic tag a sound transmittor attached to an aquatic animal to track its movements Radio tag (anterior) and acoustic http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology tag (posterior) attached to a loggerhead turtle. (Photo: ALan Rees/ARCHELON) acquired developed in response to the environment, not inherited, such as a character trait resulting from environmental effects (acquired characteristic) acquired character a non-inherited character, of function or structure, developed in an organism as a result of environmental influences during the individual's life Acropora a genus of hard (stony) corals that contain the elkhorn and staghorn corals Staghorn coral (Acropora sp.). acrorhagus a sac, covered with nematocysts, that protrudes from below the sweeper tentacles or on the column of certain anthozoans acrosome a protrusion on the anterior end of a sperm cell that contains digestive enzymes that enables the sperm cell to penetrate the layers around the oocyte (ovum) acrosphere the knobbed tentacle tip of an anthozoan, usually bearing numerous nematocysts actic pertains to littoral rocky shores as a habitat actin a contractile protein found in muscle cells. Together with myosin, actin provides the mechanism for muscle contraction http://www.coris.noaa.gov/glossary/print-glossary.html[3/10/2016 11:56:15 AM] NOAA Coral Reef Information System - Glossary of Terminology actinometer an instrument for measuring incident radiation actinopharynx the tubular throat of an anthozoan polyp that lies between the mouth and the gastric cavity; the stomodaeum actinophore a pterygiophore and its associated fin ray Actinopterygii a class of bony fishes comprising the ray-finned fishes, which make up about half of all vertebrate species known. They are found in most aquatic habitats from the abyssal depths of the ocean, greater than 10,000 m, to high altitude freshwater streams and ponds; a few species can even move about on land for short periods of time. Ray-finned fishes constitute a major human food source This squirrel fish is a member of the class Actinopterygii, the ray- finned fishes. Note the hard and soft rays in its fins. actinotroch a larval form found in the Phoronida (horseshoe worms) action potential the electrical signal which rapidly propagates along the membrane of the axon of nerve cells, as well as over the surface of some muscle and glandular cells. It is caused by change