Results for “fin”

localised

Confined or restricted to a particular place or area.

Used in 48 profiles

Mollusca

Large, highly diverse invertebrate phylum. Members are difficult to define but generally possess a soft, unsegmented body, and often a shell or shell-like structure secreted by a mantle. Includes all bivalves, cephalopods, and gastropods.

nano aquarium

Small aquarium of arguable definition. Freshwater nano-aquaria are generally accepted to hold between 5-10 US gallons (4.16-8.32 UK gallons; 18.93-37.85 litres) whereas in the marine hobby any aquarium with a volume of 30 US gallons (24.98 UK gallons; 113.56 litres) is generally considered to be a nano-system. These definitions vary, however. Also known as a nano tank.

Used in 5 profiles

nominal taxon

A nomenclatural concept denoted by an available name used in an original description, and based, actually or potentially, upon its name-bearing type but having no defined taxonomic boundaries. Often used when the precise definition of a species or genus is unclear, such as when a name may refer to more than one taxon and is therefore in need of clarification.

Used in 33 profiles

palatine

In morphology, a paired lateral bone above the mouth lying between the vomer and maxillary; the presence or absence of teeth on the palatine is a defining character in the classification of some fishes. Also known as autopalatine.

Used in 12 profiles

phylogenetic species concept

Species concept based on the evolutionary relationships among organisms, specifically using common ancestry and shared evolutionary history to define species. Under this concept a species is essentially the smallest group of organisms that share a common ancestor and can be distinguished from other such groups via phylogenetic analyses. Each such grouping constitutes a distinct branch on an evolutionary tree. Subspecies tend not to be recognised and it is generally less restrictive than the biological species concept. Often abbreviated to PSC.

Used in 1 profile

pico aquarium

Tiny aquarium of arguable definition, but generally considered to have a volume between 2.5-5 US gallons (2.08-4.16 UK gallons; 9.46-18.93 litres). Also known as a pico tank.

plesiomorphy

In cladistics, a character or trait shared by two or more taxonomic groups but derived from a remote or much earlier common ancestral form and therefore cannot be used to define a clade. Also known as an ancestral state and generally appears at the base level of a cladogram.

Used in 2 profiles

river

Vaguely-defined, generic term for a variably-sized, natural, usually freshwater, watercourse, that empties into an ocean, sea, lake, or another river.

Used in 1,266 profiles

species

Taxonomic rank into which a genus is divided, but otherwise difficult to delineate precisely with a single definition satisfying all eventualities still lacking to date. There exist a number of concepts of which the most popular in vertebrate taxonomy include the biological species concept and phylogenetic species concept.

Used in 1,790 profiles

thorax

Middle section of the body containing the main organs of circulation and respiration. Not easily defined in fishes.

Used in 1 profile

type

Can be used to refer to any taxonomic group, the characteristics of which are used for defining related, higher or lower ranking groups. For example, the type of a nominal species is a specimen (type specimen), the type of a nominal genus is the nominal species (type species), and the type of a nominal family is the nominal genus (type genus).

Used in 783 profiles