Family PYROTEUTHIDAE

Museums

Museum list

Regional Maps

Family PYROTEUTHIDAE

Compiler and date details

C.C. Lu, National Chung Hsing University, Taichung, Taiwan

Introduction

Members of the family Pyroteuthidae Pfeffer, 1912 are small, muscular squid, abundant at mesopelagic depths during the day and in the near-surface waters at night. They are easily recognised by the sharply pointed tail and the separate, almost circular fins. In common with Ancistrocheiridae, the Pyroteuthidae was considered to be a subfamily of the Enoploteuthidae until elevated to family status by Clarke in 1988. Worldwide two genera are known, each with three species. Four species, representing both genera, have been reported from Australian waters (Lu & Phillips 1985).

The arrangement, size and number of light organs in enoploteuthids are genus- and species-specific characteristics; the functional morphology of these organs has been studied intensively in various species. Like enoploteuthids and ancistrocheirids, pyroteuthids have distinctive photophores which function to provide concealment from potential predators through counter-illumination, i.e. the obliteration of the animal’s silhouette through bioluminescence from below (Young 1977, 1983).

In Pyroteuthis species, enlarged protective membranes are evident distally on the edges of the hook-bearing surface of the ventral arms of mature males; hooks are modified by the development of a secondary cusp. In Pterygioteuthis, all hooks are lost and in their place is a single chitinous plate housed in a fleshy pocket midway along the oral surface of the ventral arm. Spermatophores are transferred to the nuchal crest region of females in some species, although no structures for their storage have been described (Roper et al. 1969; Riddell 1985).

No comprehensive studies of pyroteuthid life histories in Australian waters have been undertaken. Brandt (1983) found multimodal size distributions for Pterygioteuthis gemmata Chun, 1908 from an eddy off the New South Wales coast. The same study found evidence for only a unimodal distribution in Pterygioteuthis giardi Fischer, 1895. Congeners may differ in their reproductive patterns.

Riddell (1982), working in New Zealand waters, concluded from size frequency and data on reproductive condition, that Pyroteuthis margaritifera (Rüppell, 1844) and Pterygioteuthis gemmata spawn during a single restricted period in summer; the largest mature females were larger than the males.

Pyroteuthids are short lived. The maximum age of Pterygioteuthis gemmata is estimated to be 78 days for a female of 30 mm mantle length (ML), with sexual maturity reached at 60–65 days (Arkhipkin 1997).

Pyroteuthids exhibit strong diel vertical migration: they stay below 300 m during the day and ascend to the near-surface waters at night (Lu & Clarke 1975; Roper & Young 1975).

Diagnosis

Pyroteuthids are characterised by a simple, straight funnel locking apparatus, and sharp-toothed suckers or suckers and hooks in biserial rows on the arms and arranged tetraserially on the tentacular clubs. Buccal connectives attach to the dorsal border of the ventral arms and light organs are present on the viscera and eyeballs and embedded in the tentacles, but absent on the surface of mantle, funnel, head and arms. In males, one of the ventral arms is hectocotylised. Hooks are strongly developed on the arms and tentacular clubs of Pyroteuthis species. On the tentacular club of Pterygioteuthis species, sucker rings only are present with slender, pointed teeth on their distal margins. Fins are nearly circular in outline with the sharp conus of the gladius obvious at the posterior tip of the mantle; the lateral arms are keeled.