Marine Science Dictionary (Q-Z)

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r: the intrinsic rate of reproduction of a population

r-selection: In ecology.  Organisms that reproduce rapidly and can rapidly exploit new habitats or quickly recover in the event of massive mortality.  Generally smaller organisms at lower trophic levels tend to be R-selected.  The term is derived from the variable r, used in population ecology to refer to the intrinsic rate of increase of a given population.  Contrast with K-selected

radial symetry: symmetry in animals that can be divided into two roughly symmetrical sides along any median plane.  Noticeable in the Cnidaria and Ctenophora

radula: the chitinous, rasping organ of many molluscs.  It is used for scraping and drilling in to prey, it is especially noticeable in the gastropods

refractometer: a device that measures the a liquid samples ability to refract light.  Used to infer salinity

regulation: When an animal maintains its internal variables at a level different from that of the environment it is said to be regulating. For example: the osmotic pressure within a human being's body is different from that of there surroundings (air) therefore it is an osmoregulator. Generally the ability to regulate internal variables is a trait of more "higher" organisms. An animal might be able to regulate only within a certain range of an environmental variable. See also conformity. Remotely Operated Vehicle (ROV)

Rhodophyta: The red algae, many have calcareous cell walls and are important as reef building organisms

rods: Light sensitive nerve cells that work best in low light conditions but are less able to distinguish between different wavelengths of light

Rostrum: the foremost part of the exoskeleton of some arthropods. Most noticeable in caridean shrimp.  Also refers to the extended mouth of dolphins (fam. Delphinidae) and extended snouts of some fish


salinity: the amount of ions dissolved in water, most typically reported in parts per thousand

saphrobe: organisms that feed on dead or decaying organic material

Scaphopoda: (class) Subgrouping of the Mollusca.  These are the tooth or tusk shells, these are small burrowing mollusks.  They are superficially similar to the gastropods but their shells are open at both ends

sea: any body of water more or less separated from its parent ocean This can be due to depth, archipelago or island boundaries or other land masses

seagrass: true plants, but not true grasses living completely submerged with complex rhizomes

seamount: an ocean floor feature that rises singularly more than 1000M from the sea floor

Secchi disk: A round white disk that is lowered in to the water to determine the depth that light can penetrate

sedge: (fam: Cyperaceae) plants, primarily marsh grasses.  Stems have three distinct edges

sein: A vertical net usually moved through the water, often manually

semi-diurnal tide: the condition where there are four tidal events, two high and two low per tidal day, of similar magnitude

semelparity: Where an organism expends all of its reproductive effort in one breeding cycle, then usually dies.

septa: internal walls the devide the segments of the annelid worms

sessile: living in one place on the bottom.  Many marine animals are sessile as adults with planktonic larval stages

setae: hair like projections, especially in the polychaet, annelid worms

sexual selection: A special type of natural selection where organisms choose a mate based on some characteristic

siliceous: containing or made of silicon

spawn: to reproduce so that eggs are fertilized outside of the body

species: A group of animals that, in nature are capable of producing fertile offspring.  While it might seem so, this definition is frequently not clear enough to delineate species.  Morphologies, genetic incompatibilities, physiological differences, behavior and ranges must also be considered

speciation: The event that ends with a population becoming a unique species.  Generally through allopatric or sympatric speciation.  If two populations have diverged to the point where they can not interbreed they have speciated

spicule: calcarious or celatious fibers or spines especially in sponges

spongin: protein matrix that forms the structure ("skeleton") of the demospongia

spring tide: the strongest tide of the month, occurs around full and new moon periods, when the Sun-Earth-Moon form a straight line

squaliform:  sharklike. especically small sharks. as in squaliform swimming

submarine canyon: usually the remains of a river valley that was previously exposed

steno- Gr. prefix meaning narrow, to refer to an animal that can only withstand a narrow range of some parameter.  IE an stenohaline animal can only survive within and narrow range of salinities.  Contrast with eury-

swim bladder: An extension of the gut in bony fishes that allows for buoyancy regulation

swimmeret: The abdominal appendages of some Crustacea

symbiosis: A type of interactions between individuals when two organisms live in a close relationship two one another it is termed symbiosis. Species may live on or within one another or merely within the same burrow. The animal that lives within, or on the other is said to be the symbiont. The other animal is said to be the host. Symbiotic relationships in which the host suffers and the symbiont benefits are referred to as parasitism and the symbiont is said to be a parasite. Relationships where there is no effect on the host are said to be commensalism and the symbiont is said to be a commensalist. When both parties benefit the relationship is said to be mutualistic

sympatry: When a population of a species is together and gene flow is possible.  The term is most often used to refer to sympatric speciation.  This is when some members of a population adapt to exploit a different resource than others, and they diverge.  It can also be used to describe the development of traits or behaviors.  Contrast with allopatry

synapomorphy: a derived characteristic shared by sister taxa


tagma: Fused body sections in arthropods.  Head thorax and abdomen in insects, cephalothorax and abdomen in Crustacea

telson: The last portion of the exoskeleton in arthropods.  Noticeable in the horseshoe crab, Limulus sp. as the tail

temperature: the average kinetic energy of the particles in a sample of matter

territoriality: When an animal acts to exclude other individuals from some physical space

territory: an area defended by an individual

tetrapoda: This term refers to vertebrate animals which have evolved to live on land. Vertebrate animals which have evolved to live in the sea from ancestors which lived on land are said to be marine tetrapods. They include the marine mammals and marine reptiles. Groups of marine mammals include the whales, dolphins and porpoises (order Cetacea), the manatees and sea cows (order Sirenia), and the seals, sea lions, and walruses (order Pinnapedia). Marine reptiles include the sea turtles (order Chelonea) and the sea snakes (order Squamata)

theory: statement of facts or principles based on and explaining observations from nature.  A viable scientific theory is able to make predictions concerning the outcome of experiments or studies

tide: the periodic rise and fall of water dues to the gravitational effects of astronomical bodies, primarily the sun and the moon.  Different areas of the world have different tide strengths and different numbers of tide events each day.  (See mixed tide, diurnal tide, semi-diurnal tide) tide events also vary in strength throughout the month (see spring tide, neap tide)

tissue layer: a developmental stage of embrios, there are two or three tissue layers- epidermis (outermost) epidermis/gastrodermis (indermost lining of the gut) and mesodermis: the middle layer

torsion: The twisting of gastropod shells

totipitant: A cell that can differentiate into other cell types

transparency: the ability of light to pass through water, a measure of water clarity

trophic: refers to feeding, as in trophic levels such as herbivore, carnivore etc

turbidity: the cloudiness of a liquid sample, usually due to suspended material (mud) or biological material
tube feet: extension in the water vascular system of echinoderms that serves as a locomotor appendage
U - Z

upwelling: the result of Ekman transport, when deep colder water replaces surface water moved via Ekman transport.  Upwelling zones are most common along the western coasts of continents with rapid drop offs.  Upwelling areas are usually highly productive do to the cold, nutrient rich water

Vertebrata: (subphyla) Sub-grouping of the phylum Chordata.  Animals which have lost there notochord at some point in there ontogeny.  It is replaced by a cartilaginous or bony jointed spine or backbone.  The backbone is jointed and the individual bones are called vertebras

viviparity: Type of development in which the yolk joins with the amniotic tissue to form a placenta and young are born live.

-vore L. prefix refers to what an animal eats, as in herbivore, an animal that eats plants.

warm blooded: An archaic, layperson's  phrase for both the terms edotherm and homeotherm.

water vascular system: system of canals in echinoderms that circulates respiratory gasses and nutrients

yolk: energy storage in the egg

zeitgeber: environmental cue that keys a biorhythm   

zooid: A single member of a colonial organism as in a hydra or bryozoan

zooplankton: Any plankton that is a consumer, usually from the animal kingdom but also includes animal like protists  see pic

zooxanthellae: dinoflagellates that are endosymbiotic with some animals, esp coral polyps