Results for “várzea”

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.

placoid scale

Tooth-shaped scale-type found in certain fishes, e.g., sharks, rays. Structurally homologous with vertebrate teeth.

planaria

Generic term applied to numerous non-parasitic flatworms of the class Turbellaria. Also a genus within that class, Planaria. Various species occur in aquaria where they're most often associated with accumulation of uneaten food or organic material and normally considered pests.

planktonic bloom

A visble population explosion in plankton, typically involving phytoplankton, and normally resulting from an increase or excess of available nutrients.

poikilotherm

An organism having a body temperature that varies with the temperature of its surroundings; a cold-blooded organism.

polymorphism

The occurrence of different forms, stages, or types in individuals or multiple organisms of the same species independent of sexual variation.

Used in 2 profiles

pored scale

A scale possessing a visible pore, e.g. a lateral line scale.

Used in 38 profiles

postoral pouch

A transverse, hollow, pouch-like structure opening anteriorly and located on the ventral surface, immediately posterior to the mouth, in some members of certain balitorid genera, e.g., Gastromyzon, Neogastromyzon.

Used in 13 profiles

prefilter

A preliminary filter or filter stage, most often used to trap solid particles via mechanical filtration prior to a biological or chemical stage.

principle caudal-fin rays

Fin rays forming the dorsal or ventral margins of the caudal fin, supported by the supported by the hypural and parahypural.

Used in 1 profile

progenesis

Form of paedomorphism characterised by retention of juvenile features in an adult individual via accelerated maturation.

protein skimmer

Mechanical device used to remove organic compounds in marine aquaria via the process of foam fractionation.

Used in 1 profile

pseudobranch

Accessory or spurious gill, often located on the inner surface of the operculum in various fishes, that is usually small and sometimes completely obscured beneath the epithelium. Also referred to as pseudobranchia.

pterygiophore

Bony or cartilaginous structures via which the rays of the median fins articulate and connect to the body.

Used in 31 profiles

redescription

New, updated, corrected or more complete version of a species description.

Used in 13 profiles

reduction

Chemical process whereby an atom or ion gains electrons and undergoes a subsequent increase in valence; the act or process of being reduced. Opposite of oxidation.

Used in 60 profiles

refractometer

Instrument used to measure salinity or specific gravity via the refractive index (basically, the degree that light bends when shined through something) of a liquid. Most models are designed to measure sodium chloride or brine solutions and not seawater which contains a more complex range of salts and minerals, but usually more accurate than a hydrometer nevertheless.

reproduction

Production of offspring via a sexual or asexual process.

Used in 111 profiles

resource partitioning

Form of niche differentiation by which two species partition (divide) a resource based on behavioral or morphological variation in order to ensure their mutual survival by reducing competition.

Used in 11 profiles