Psychroteuthis glacialis Thiele 1920

Introduction

Psychroteuthis glacialis is a muscular squid of moderate size (44 cm ML) (Nesis, 1982). Studies in the Weddell Sea found that "this is the most abundant muscular squid in the Weddell Sea and the only pelagic cephalopod which occurs in considerable numbers in the Antarctic Sea Ice Zone" (Piatkowski and Steimer, in manuscript). The species is a major prey item for predators such as large fish, birds, seals and toothed whales in Antarctic waters.

A specimen of the second possible species was taken from the stomach of a sperm whale captured off the Bonin Islands in the North Pacific (Nesis, 1982) and Roper et al. (1969) suggest that there may be two species in Antarctic waters. Little is known about the ecology of this squid in spite of its importance in the Antarctic ecosystem.

Brief diagnosis:

A member of the histioteuthid families ...

• without integumental photophores on head, arms or mantle.

Characteristics

1. Photophores
   1. Tips of third arms of mature males with large glandular structures, similar structures on tips of arms II-III of mature females. These structures are presumably photophores; otherwise photophores absent.
      

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      Figure. Immature female of P. glacialis with photophores developing on arms III (arrows). © Michael Vecchione.

2. Tentacles
   1. Club with suckers not in uniform series; four to seven suckers in a transverse row.
   2. Locking apparatus extends distally along the dorsal side of the stalk and proximally along the ventral side.
      
      

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      Figure. Oral view of the tentacular club of P. glacialis, 405 mm ML, Ross Sea, Antarctica. Photograph by Peter Marriott.

      
      
3. Head
   
   1. Beaks: Descriptions can be found here: Lower beak; upper beak.
      
      

Nomenclature

A list of all nominal genera and species in the Psychroteuthidae can be found here. The list includes the current status and type species of all genera, and the current status, type repository and type locality of all species and all pertinent references.

Life History

Size-frequency data suggests a two-year life-cycle with males maturing sooner and at a smaller size than females (Piatkowski and Steimer, in manuscript).

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Figure. Two views of a paralarva of P. glacialis captured in the Ross Sea, Antarctica. It shows striking similarity to paralarvae of the Histioteuthidae in the shape of the fins, tentacular club with small suckers compared to those of the arms, and the anterior position (i.e., adjacent to the cephalic cartilage) of the digestive gland. Photographs by D. Stevens.

Distribution

Vertical distribution

In the Weddell Sea, P. glacialis was taken between depths of 230 and 920 m with bottom and bentho-pelagic trawls (Piatkowski and Steimer, in manuscript).

Geographical distribution

P. glacialis has a circumpolar distribution in Antarctic waters. A map of their distribution can be seen here.

Other Names for Psychroteuthis glacialis Thiele 1920

• Psychroteuthidae Thiele 1920

References

Gröger, J., Piatkowski, U. & Heinemann, H., 2000. Beak length analysis of the Southern Ocean squid Psychroteuthis glacialis (Cephalopoda: Psychroteuthidae) and its use for size and biomass estimation. Polar Biology, 23(1): 70-74.

Nesis, K. N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.

Piatkowski, U. and S. Steimer (In manuscript) The glacial squid Psychroteuthis glacialis: distribution in the Weddell Sea, Antarctica. Antarctic conference abstract.

Roper, C. F. E., R. E. Young and G. L. Voss (1969). An illustrated key to the families of the order Teuthoidea. Smiths. contr. zool., 13:1-32.