Spined pygmy shark

Taxobox
name = Spined pygmy shark
status = LC | status_system = IUCN3.1
trend =


regnum = Animalia
phylum = Chordata
classis = Chondrichthyes
subclassis = Elasmobranchii
ordo = Squaliformes
familia = Dalatiidae
genus = "Squaliolus"
species = "S. laticaudus"
range_

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range_map_width = 200px
range_map_caption = Range of spined pygmy shark (in blue)
binomial = "Squaliolus laticaudus"
binomial_authority = Smith & Radcliffe, 1912

The spined pygmy shark, "Squaliolus laticaudus", is a sleeper shark of the family Dalatiidae with a circumglobal distribution between latitudes 48° N and 40° S, at depths between 200 and 1,200 m. Its length is up to 22 cm.

The spined pygmy shark is a very small dogfish with a large eye (diameter 73 to 86% of interorbital width). This species is the holotype of the genus which has the following distinctive features: fin spine on its first dorsal fin but not on its second dorsal fin; second dorsal fin long-based and low, about twice the length of first dorsal fin base; first dorsal-fin base closer to pectoral fins than to pelvic fins; and the caudal fin nearly symmetrical, paddle-shaped, with a subterminal notch present. There are low lateral keels on caudal peduncle. The body is cigar-shaped, with a very long bulbously conical but slightly pointed snout. The mouth is ventral with thin lips and teeth strongly different in both jaws, uppers small, narrow and erect cusps, lowers larger, blade-like and semi erect.

It is an oceanic, wide-ranging, tropical pelagic species occurring near continental and insular land masses, sometimes over the shelves, but usually over the slopes. It undergoes vertical migrations on a diel cycle, seen at the bottom during the day and travels to 200 m at night. Feeds on deepwater squid, lanternfish, gonostomatids and idiacanthids, and probably follows its prey on their diel migrations.Has well-developed photophores densely covering the ventral part of the body and sparsely seen on the sides and hardly developed on the dorsal surface.

Reproduction is ovoviviparous.

Coloration is dark with conspicuously light-margined fins - the edges of fins have bright borders.

References

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