Decapoda: (order) This group
includes the crabs, true shrimp, crayfish, and lobsters, among others. Theey include most of the commercially important crustaceans.
They are very diverse and are linked in that all have five pair of walking legs, with the first usually modified into chelae
layer: concentration of pelagic animals at the mesopelagic border that migrate upward nightly- so called because it
disrupts sonar signals.
Similar to benthic. Animals associated with the ocean floor or structure. This is more often used to refer to fish.
density: in physics or chemistry
the unit mass per unit volume. In ecology frequently the number of individuals within a given area (population density.)
detritus: broken up parts of
dead, decaying organic material
detritovore: animals that eat detritus, detritovores allow for the rapid recycling of organic material
that would otherwise be lost to an ecosystem
diadromous: A lifestyle of where fishes live in two areas with different salinities within there life cycle.
See also catadromous and diadromous
diatoms: (fam. Diatomacea) single celled (often colonial)aquatic algae. Diatoms are characterized by having
a two part siliceous cell wall or "frustule." They are an important component of the phytoplankton in many environments,
especially higher latitudes.
The break town of materials for utilization as energy or building blocks.
dinoflagellate: (order Dinoflagellata) single celled aquatic algae
with a cellulose cell wall and two locomotor flagella. The are an important component of the phytoplankton in many areas.
Dinoflagellates may bloom and cause toxic red tides, some are endosymbiotic with animals and many are bioluminescent.
directional selection: type of
natural selection, when one extreme of a trait is selected. Accounts for rapid evolution of a single species.
disphotic zone: The depths of
the ocean without plentiful light penetration, and very little photo synthesis. The actual depths of the disphotic zone depend
on the turbidity of the water.
selection: type of natural selection, when two extremes of a trait are selected. Accounts for rapid speciation.
diurnal: During the day, within
the day. Animals which are active during the daylight. Contrast with crepuscular and nocturnal.
diurnal tide: the condition where there
are two tidal events, one high and one low per tidal day.
divergent evolution: When traits with a similar form or purpose become dissimilar,
filling different roles. Animals that are similar become less similar. An example of this would be the walking
limbs of land turtles and the flipper limbs of sea turtles. At one time these animals had a common ancestor, but evolved
to exploit very different resources. Contrast with convergent evolution. See also homologous
diversity: see biodiversity
dissolved oxygen (DO): the amount of
oxygen dissolved in a sample (of water) usually between 0-10 parts per million (milligrams per liter) or in percent saturation.
Colder water can hold more dissolved oxygen.
-dont: Refers to teeth or tooth structure, as in heterodont, meaning "different teeth."
dormancy: a period of inactivity,
usually in plants
refers to the upper side of bilatteraly symmeterical organisms, especially the fishes
ebb tide: the tide condition/ state when the water is falling, when the next
tide event is a low tide
The act of shedding and exoskeleton, as arthropods must do periodicaly during growth.
Echinodermata: (phyla) These are marine animals characterized primarily
by a spiny endoskeleton and a water vascular system. Echinoderms are, oddly enough an very advanced group of animals. They
are scizocoelus meaning that there body cavity is formed by a split in the mesoderm. This is characteristic of the higher
animals including the vertebrates. This group exhibits much diversity. There are four major classes separated mainly by body
form. The Asteroidea are the sea stars. The Ophiuroidea are the brittle stars. The Echinoidea are the sea
urchins and sand dollars. The Holoththuroidea are the sea cucumbers
ecosystem: The sum of all biotic (living) and abiotic (non living) factors
in a given area.
Any animal that does not contain the heat (energy) produced by its metabolic processes. This is generally a trait of
lower animals. See also heterotherm, contrast with endotherm.
egestion: The removal of the unusable materials
Ekman spiral, Ekman transport- when the deeper layers of a body
of water tend to veer to the right or left (Coriolis effect) and the net movement of a current is at a right angle to the
when animals leave a population. Contrast to immigration.
endemic: When an animal is native to an area it is said to be endemic to that area. This
may also be used to refer to a species that is unique to a given area.
endoderm: (endodermis) inner tissue layer, synonymous with gastroderm
endogenous: originating internally,
as in an internal mechanism
Generally the internal cartilaginous and or calcified skeleton of the vertebrates
endotherm: Any animal which contains (turns inward) some of the
heat form its metabolic processes. This is generally a trait of higher animals. See also homeotherm, contrast
Epipelagic and epibenthic refer to the upper reaches of the ocean. The epi zone generally extends from the ocean surface to
a depth of 200m. An animal that is benthic and lives in the epi zone would be epibenthic when a pelagic animal in the epi
zone would be epipelagic see picture
epiphyte: A plant or algae which grows on something, usualy another
organism-plant or animal
the outer developmental tissue layer, forms nerves, skin and exoskeleton
eutrophic: large amounts of available nutrients, this usually causes
an overabundance of simple algaes that choke ecosystems.
eukaryote: organisms that have membrane bound organelles in their cells, includes all plants,
animals, fungi and protists
(order) Shrimp like crustaceans which occur in large numbers in the higher latitudes. These are the "krill" which
are a very important link in the Arctic and Antarctic food webs
eury- (prefix): This prefix denotes the ability of an organism to live within a wide
range of environmental factors, for example a eutyhaline organism can survive within a wide range of salinities. See also
(biological): A change in allelic frequencies in successive generations. Alos used to refer to the theory that all organisms
have evolved from common ancestors with modification, leading to the diversity of life on earth
excretion: Ridding the body (on an organismal level) or the cells
(on a cellular level) of wastes from biological process
exoskeleton: The hard jointed covering of arthropods, made of chiton. The exoskeleton
does not grow, and as the animal grows it must molt, or undergo ecdysis in order to have an exoskeleton of the correct size
exotic species: a species introduced
to an area that (usually) displaces natural species.
endemic: Organisms that are native to an area, animals that evolved within an area or habitat
endo: Inside of, the inner
that grow on top of other things, especially other organisms
eury- gr. prefix meaning broad, adapted to withstand a wide range of some parameter.
IE an euryhaline animal can withstand a wide variation in salinity. Contrast with steno-
Eubacteria: (kingdom) the "modern" bacteria, characterized
by distinct cell walls that contain peptidoglycan
evolution: A change in the allelic frequency of a population over time. Also refers to the theory that
all organisms are descended from previously living organism through descent with modification
evolutionary stable strategy (ESS): A behavioral or morphologic
strategy that offers the optimal cost-benefit ratio. Can not be bettered if widely adapted by most individuals in a
species or group of organisms which have living representatives today
extinct: Any species or group of organisms which do not have living representatives