Family PYROTEUTHIDAE Pfeffer, 1912

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• PYROTEUTHIDAE Pfeffer, G. 1912. Die Cephalopoden der Plankton-Expedition. Zugleich eine monographische Ubersicht der Oegopsiden Cephalopoden. Ergebnisse der Plankton-Expedition der Humboldt-Stiftung 2: 1-815 pls 1-48.

  Type genus:

   Pyroteuthis Hoyle, 1904.

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, Pyroteuthis with three species, and Pterygioteuthis with four 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.

General References

Arkhipkin, A.I. 1997. Age of the micronektonic squid Pterygioteuthis gemmata (Cephalopoda; Pyroteuthidae) from the central-east Atlantic based on statolith growth increments. Journal of Molluscan Studies 63: 287-290

Brandt, S.B. 1983. Pelagic squid associations with a warm-core eddy of the East Australian Current. Australian Journal of Marine and Freshwater Research 34: 573-585

Clarke, M.R. 1988. Classification of the genera of recent cephalopods. pp. 4-7 in Clarke, M.R. & Trueman, E.R. (eds). Paleontology and Neontology of Cephalopods. The Mollusca. Vol. 12. San Diego; London : Academic Press.

Lu, C.C. & Clarke, M.R. 1975. Vertical distribution of cephalopods at 11°N, 20°W in the North Atlantic. Journal of the Marine Biological Association of the United Kingdom 55: 369-389

Lu, C.C. & Phillips, J.U. 1985. An annotated checklist of Cephalopoda from Australian waters. Occasional Papers of the Museum of Victoria 2: 21-36

Riddell, D.J. 1982. The systematics, distribution and biology of the Enoploteuthidae (Cephalopoda : Oegopsida) in the New Zealand region. Unpublished MSc Thesis, University of Auckland New Zealand 102 pp.

Riddell, D.J. 1985. The Enoploteuthidae (Cephalopoda: Oegopsida) of the New Zealand region. New Zealand Fisheries Research Bulletin 27: 1-52

Roper, C.F.E., Young, R.E. & Voss, G.L. 1969. An illustrated key to the families of the order Teuthoidea (Cephalopoda). Smithsonian Contributions to Zoology No. 13: 1-32

Roper, C.F.E. & Young, R.E. 1975. Vertical distribution of pelagic cephalopods. Smithsonian Contributions to Zoology No. 209: 1-51

Young, R.E. 1977. Ventral bioluminescent countershading in midwater cephalopods. pp. 161-190 in Nixon, M. & Messenger, J.B. (eds). The Biology of Cephalopods. Symp. Zool. Soc. Lond. No. 38. London : Academic Press.

Young, R.E. 1983. Oceanic bioluminscence: an overview of general functions. Bulletin of Marine Science 33(4): 829-845

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