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Marine Science Dictionary (A)

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A
 
A- or An-  Without, or not, as with abiotic, "without life" or anhydrous, "without water."

abiotic: Non living, without life.  The abiotic components of an environment include the chemical and physical components of that system.  For example, the temperature or the salinity of the water in which an organism lives, contrast with biotic.

aboral: the side of a radially symetrical animal away from the mouth

abysso: (pelagic/benthic) These refer to the lower regions of the ocean. The abyssal zone generally extends from 4000m to 6000m. An animal that is benthic and lives in the abyssal zone is said to be abyssobenthic when an pelagic animal would be abyssopelagic see picture

acclimatization: A change in the function of an organism that happens within its lifetime.  IE the abilty of salmon to move in to freshwater after having spent the majority of their lives in salt water.  Contrast with adaptation
                             
acoelomate: animals that do not have fluid filled cavities housing internal organs, flatworms are acoelomate animals

adaptation: A trait, in form, function or behavior which infers some selective advantage. This trait will (or has been) passed from generation to generation and they become fixed in the genetic code.  Adaptations happen in the context of evolutionary time.  Contrast with acclimatization

adaptive: any thing, morphologic change, behavior etc that positively effects an organisms evolutionary fitness.

adaptive radiation: when an ancestral organism adapts to fill a variety of ecological niches, giving rise to new subspecies or species.

agonistic (agonism): noxious behavior that has an influence on the behavior of conspecifics

algae: catch all term for aquatic photosynthesizers that are not true plants,  includes many colonial forms that may have a plant like appearances as well as unicellular forms

allele: a potential form of a gene, typically when there are variations in genetically controlled traits

allopatry: When species or populations of species are separate.  Gene flow between the populations is impossible or very rare.  It is most often used to refer to allopatric speciation.  That is, when some event separates a contiguous population into two separate populations and they diverge from one another.  It can also be used to describe the development of traits or behaviors.  Contrast with Sympatry

altricial: The young of animals born more or less helpless.  Unable to protect themselves, or unable to move normally.

ambulacra: the groove where tube feet come out of the arms/rays of echinoderms

Amphipoda: (order) Small common crustaceans usually characterized by lateral compression and several types of legs some of which are proportionately very large

Ampuli of Lorenzini: fluid filled electrosensory organs in the snout of cartilaginous fishes

Ampule, ampuli: a small bulb, especially at the top of a pipet or on the tube feet of echinoderms

anadromous: A diadromous (see diadromous) lifestyle in fishes where the adults live in a marine environment, returning to freshwater to spawn.  Perhaps the best example of this are the Pacific and Atlantic salmon (genus: Salmo).  Contrast with catadromous.

anaerobic bacteria: eubacteria that metabolize in anoxic environments,  they are very importantin the recycling processes in nearshore environments.

analogous: In evolution, when physiolgic or morphological traits with similar purposes evolve from different ancestral sources.  An example would be the fins of fish compared to the flippers of marine mammals.  Both serve to propel the animals through the water but evolved separately.  Contrast with Homologous.  See also convergent evolution.

anquiliform: "eel like" refers to the order (anguilliformes) of true eels.

anhydrous: without water

Annelida: (Phyla) Any coelomate worm characterized by the presence of multiple similar segments, and often the presence of setae, the Annelids are the segmented worms. This group is divided into three major classes

anoxic: without oxygen, water that has not oxygen dissolved in it.

appetitive: trait or character that is variable, not identical within species, contrast with consummatory.

aphotic zone: The depths of the ocean to which light cannot penetrate and photosynthesis cannot occur.

aplacental viviparity: giving birth to live young that are never attached to the mother. AKA ovoviviperous

aposematism (aposematic): warning coloration, usually in noxious organisms.

appendicular skeleton: The bones of the limbs of vertebrates, including the paired fins of fishes.  There are to divisions to the appendicular skeleton, the pectoral girdle and pelvic girdle, or fore and hind limbs respectively.

aquaculture: production of aquatic organsisms in an artificial or controlled habitat, usually for profit

Archae or Archaebacteria: (kingdom, subkingdom) Bacteria that are able to survive in environments of  extreme chemistry and temperature.  Archaebacteria lack peptidoglycan in their cell walls

Aristotle's Lantern: five part mouth of echinoids (sea urchins and sand dollars)

Arthropoda: (phyla) Invertebrate animals characterized by segmented  bodies, protected by an exoskeleton and the presence of jointed appendages (arthro = joint and pod = leg).  With over one million species the arthropods are the most diverse phyla of animals.

artificial reef: submerged habitat created from old ships, car bodies, construction rubble, specially made materials etc usually for the purpose of atracting fishes for capture or for recreational SCUBA diving

Aschelminthes: Group of eight or so phyla, characteristically pseudocoelomate. Worm like, with molted cuticle and a triangular pharynx

atoll: any somewhat circular island formed by a coral reef.  Atolls take this shape because the volcanic island that they have formed around has eroded away or subsided and the coral continued to grow.

autotroph: Any organism which  produces its own energy from inorganic substances is said to be an autotroph.  Immediately we think of plants which turn light energy into organic, stored, chemical energy.  Organisms which do this are said to be photoautotrophic, photo referring to light.  There are other photoautotrophs, notably many of the cyanobacteria.  There are also many bacteria which can turn a surprising diversity of inorganic substances into stored energy.  These are the chemoautotrophs.  Autotrophs are the first link in any food chain.  Without them life on earth could not exist.  Contrast with heterotroph.  Synonymous with producer.

autonomous underwater vehicle: A robitic device that is able to work underwater without imput from an operator (past initial programing.)

asexual: Without sex, usually referring to asexual reproduction (cloning or budding).

assimilation: When materials from the environment are included in the construction of new biotic materials to be incorporated in to an organism.

autogenic: originating from within, as in an autogenic body part, or an autogenic response

axial skeleton: The skull and spinal column of vertebrates. Includes the median fins of fishes