Marine Science Dictionary (F-L)

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fauna: All the animals endemic to, or living in, an area are the fauna of that area

feral: A domesticated animal which has escaped or been released into the wild.  The term is also used to refer to colonies of previously domesticated animals.

filter feeding: Feeding mode that requires the intake of large amounts of planktonic organisms.  Usually accomplished by moving through the water with an open mouth or pumping water across some type capture apparatus

fins (on fish): Any spiny, rayed or fatty (adipose) appendage on fish. Fins may be paired or median. Paired fins are ones that occur on each side of the fish. Median fins occur along the centerline of the body. Fish are often identified by the presence, purpose or location of fins see pic

flipper: The modified fore limb of marine tetrapods

fish: any aquatic, gill breathing vertebrate with fins

fitness: The ability of an organism to contribute its genes to future generations.  There is no absolute measure of fitness, and it is a relative term.  Variable traits, which are coded for by genes, increase an organism's fitness (make it more fit).  Changes in the environment can change an organism's fitness

flood tide: the tide condition/ state when the water is rising, when the next tide event is a high tide

flora: All the plants endemic to, or living in, an area are the flora of that area

fluke: The tail, caudal, or back fin, of marine mammals. The fluke is evolved from the tetrapod tail

frustule: see diatom


gamete: A haploid sex cell usually sperm or ovum

gastroderm: the inner tissue layer, makes up the digestive tract

Gastropoda: (class) Sub-grouping of the Mollusca.  These are the snails, conchs, limpets, and whelks as well as shell-less forms like nudibranchs, slugs, and sea hares

gene: A section of DNA that codes for a particular protien

genetic drift: A factor in biological evolution that implies random changes in allelic frequency.  This is more important in smaller populations and more of a factor in allopatric speciation

geologic time:

gill: a vascular surface area used for O2 CO2 diffusion. Fishes, crustaceans, and mollusks have gills that evolved independently

guyot: a seamount that was once above water, and shows the signs of erosion, a flat topped sea mount


habitat: where an organism lives, the environmental needs of an organism

hadal: Hadal refers to the deepest layers of the ocean generally 6000m and below
see picture

haploid: a state of having one half the normal pair of chromosomes, unpaired chromosomes

Hardy Weinberg Equilibrium: A state of stability in a populations gene pool

hemoglobin: Oxygen binding respiratory pigment based on the iron ion.  Turns red when oxygenated.  Common in vertebrates

hemocyanin: Oxygen binding respiratory pigment based on the copper molecule.  Turns blue when oxygenated.  Common in crustaceans and mollusks

herbivore: an organism that feeds primarily on photoautotrophs

hermaphroditic: (hermaphrodite) Animals which contain both mature male and female sex cells at some point within there life cycle are said to be hermaphrodites. Animals which are females first and then become males are said to be protogynous hermaphrodites. Animals which are males first and then become female are said to be protandrous hermaphrodites. Animals which contain mature male and female sex cells at the same point in there life are said to be synchronous hermaphrodites

hetero- Gr. prefix meaning not the same, contrast with homeo

heterotherm: Any animal that has a fluctuating body temperature, usually fluctuating with the environment.  The term heterothermy is often used synonomously with ectothermy (see ectothermy).  This, however, is a mistake.  For example, many large pelagic fishes, are able to turn there body heat inward, and maintain a body core temperature several degrees above that of the environment.  Contrast with homeothermy

heterotroph: Any organism which derives energy from organic material stored in the make up of other organisms is said to be a heteratroph.  See also autotroph, consumer, predator and saphrobe

Hirudinea: (class) a subgroup of the phylum Annelida.  Characterized by the absence of setae and a specialized sucking mouth.  They are mostly terrestrial.  The leaches.
holoplankton: see plankton

homo- or homeo- Gr. Prefix similar, or the same, contrast with hetero

homeostasis: The tendency of organisms to maintain a stable internal environment

homeostatic mechanism: A series of physiological processes that maintain homeostasis

homeotherm: Any animal which has a constant body temperature.  Usually different from that of the environment.  The term Homeothermy and ectothermy (see ectotherm) are often used synonomously.  This, however, is a mistake.  For example, a deep sea organism, living in a constant environment,  is a homeotherm.   It does not fit the definition of an endotherm.  Contrast with heterotherm

homologous: In evolution, when similar traits or morphologic characteristics evolve to serve quite different purposes.  An example would be the flippers of marine mammals compared to the limbs of terrestrial vertebrates.  In ancestral  forms they where both used for movement on land,  in the marine mammals, the appendages became adapted to move through water.  Contrast with Analogous.  See also divergent evolution

hydrometer: device used to measure the specific gravity of a liquid sample, used to infer salinity

hypothesis: A testable statement of expected outcome of a study or experiment

hypoxic: ichthyo- Gr. prefix  referring to fish as in ichthyophile, meaning, "fish lover."


immigration: when individuals come in to a population.  Contrast to emigration.

interstitial: small organisms that live between grains of sand

Isopoda: (order) Small common crustaceans characterized, generally, by one type of leg

iteroparity: where an organism may have multiple reproductive events within its lifetime.  Reproductive effort is spread through multiple breeding cycles

k: See carrying capacity

k-selection: In ecology.  Organisms that are adapted to a stable environment.  k selected organisms generally reproduce slowly, producing only the amount of young that the community can support.  They are dependent on a stable environment.  Generally larger organisms, higher on the food chain tend to be k-selected.  The term is derived from the variable K which is used to denote the carrying capacity of a community.  Contrast with r-selection

kelp: members of the group Phaophyta, the brown algae, that form large plantlike colonies.  The holdfast, stipe and frond are analogous to the root, stem and leaf of true plants.  Although they may reach 200 feet in length kelps lack true tissues.

keratin: a protein which makes the external surfaces of organisms stiff or hard, as in the epidermis of vertebrates and the scales of fishes

krill: see Euphausiacea


larva: the young of an animal usually not morphologically similar to the adult

lateral line: a series of pores along the sides of fishes that sense pressure or movement

lectitrophic: larval forms that get their energetic needs from yolk, more energy is spent in the development of each larvae, time in the plankton, dispersal time, is reduced

lipid: one of four primary types of organic molecules serves as energy storage and in cellular construction

littoral zone: This is generally the region near the ocean shore that is exposed during low tides and covered during high tides, between the high and low tide lines. There is also a supralittoral zone which includes areas above the high tide line which is affected by the ocean in the form of salt spray or tidal swash and a sublittoral zone which includes the areas from the low tide line to the edge of the continental shelf see pic

lung: An internal air sack that allows for the diffusion of oxygen in to the circulatory system.  The vertebrate lung develops as a branch of the embryonic digestive system, homologous to the swim bladder in bony fishes