Bassia bassensis

Bassia is a monotypic siphonophore genus in the family Abylidae. The genus contains the single species Bassia bassensis.^[5]

Bassia bassensis
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Hydrozoa
Order:	Siphonophorae
Family:	Abylidae
Genus:	Bassia L. Agassiz, 1862[1]
Species:	B. bassensis
Binomial name
Bassia bassensis (Quoy & Gaimard, 1833)[2]
Synonyms[3][4]
Genus synonymy Sphenoides Huxley, 1859 Species synonymy Abyla bassensis Huxley, 1859 Abyla pentagona Mayer, 1900 Abyla perforata Gegenbaur, 1859 Bassia obeliscus Haeckel, 1888a Bassia quadrilatera Haeckel, 1888b Bassia tetragona Haeckel, 1888b Calpe bassensis Lesson, 1843 Diphyes bassensis Quoy & Gaimard, 1833 Sphenoides australis Huxley, 1859 Sphenoides obeliscus Haeckel, 1888a Sphenoides perforata Haeckel, 1888a

Description

The species reaches body lengths of 6–8 cm. The body plan is radially symmetric around a central mouth, with a polyhedral shape bearing 4 main ridges which end in short basal teeth. The species is bioluminescent and has a bluish tint on the ridges of the nectophores and is covered in gelatinous sheets that form a "box" around the mouth.^[6] As in all cnidarians, there is a single gastrovascular cavity (the coelenteron) and the mouth acts as both mouth and anus; it is surrounded by a layer of tentacles bearing nematocysts.^[7]

Distribution

Bassia bassensis is common in warmer and tropical waters in the Atlantic and Pacific oceans, specifically around the African and Asian coasts.^[8] It is common in the Humboldt Current system,^[9] along with other gelatinous zooplankton off the coast of South America, where three currents mix together. The species is generally found in the top 50 meters of the epipelagic zone of the ocean.^[10]

Ecology

The species primarily preys on copepods in the 0.4-1.2 mm size range.^[10]

Populations can be among the most abundant species of siphonophores. Abundance may be impacted by small variations in salinity and temperature, leading to great increases at temperatures below 28 degrees Celsius, and dwindling in temperatures greater than 28.5 degrees.^[11] Enough food availability in the concerned areas might mitigate the negative effect of low or high salinity waters, given the positive and significant relationship between siphonophore WDV and zooplankton wet weight biomass.^[12]