Taxonomic group into which a family is divided and which contains one or more species characterised by a shared trait or traits. The generic name is used, either alone or followed by one or two specific epithets, to form a binomen or trinomen.

Period of embryonic development in a viviparous organism.

Abbreviation for general hardness.

Respiratory organ of fishes and some other aquatic organisms comprising a highly-vascularised membrane or outgrowth.

Bony or cartilaginous arch in the pharynx to which the gill filaments and rakers are attached.

Chambers located on either side of the head into which the gill filaments project.

See operculum.

Comb-like lamellae found in the gills, through which oxygen is extracted and carbon dioxide expelled.

Type of net normally suspended vertically in such a way that fish become ensnared by their gills.

Opening connecting the gill chamber to the exterior environment. Also referred to as the gill slit.

Any of the bony processes located on the gill arch which function to either retain food items or otherwise prevent solid matter from entering the gill chamber. Vary in number and size depending on taxon and therefore useful in identification.

See gill opening.

The distance around something; circumference; size; bulk.

Cell, cell group, or organ secreting a substance used elsewhere in the body.

Of or relating to the jaw.

Any organ that produces gametes, e.g., a testicle or ovary.

Former supercontinent also known as Gondwanaland existing from approximately 510 to 180 Mya and comprising the majority of the landmasses in today’s Southern Hemisphere, including Antarctica, South America, Africa, Madagascar and the Australian continent, plus the Arabian Peninsula and Indian subcontinent.

Modified anal fin used in copulation for the transfer of male gametes to a female. In many cases only the anterior part of the fin is modified.

Method of differentiating bacterial species into groups based on the structure of their cell walls, using a particular, violet-coloured, staining technique.

Of, relating to, or being a bacterium that does not retain the crystal violet dye used in Gram's method of staining.