A review of the biology of the diamondback squid, Thysanoteuthis rhombus (Oegopsida: Thysanoteuthidae)
Nigmatullin, C.M.; Arkhipkin, A.I. (1998). A review of the biology of the diamondback squid, Thysanoteuthis rhombus (Oegopsida: Thysanoteuthidae), in: Okutani, T. Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. pp. 155-181
In: Okutani, T. (1998). Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. Japan Marine Fishery Resources Research Center: Tokyo. 269 pp., more
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| Authors | | Top |
- Nigmatullin, C.M.
- Arkhipkin, A.I.
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| Abstract |
The diamondback squid Thysanoteuthis rhombus Troschel, 1857 is a large nektonic squid occurring worldwide in oceanic tropical and sometimes, subtropical oceanic waters. Distribution and migrations of T.rhombus depend on the surface circulation of oceanic waters. Despite its nektonic shape, T. rhombus is a relatively inactive migrant that undertakes long seasonal migrations in the waters of warm peripheral oceanic currents. During a major part of the life cycle, T. rhombus does not move actively, but is propelled slowly by undulations of its long triangular fins. However, when it encounters danger T. rhombus is capable of making one or several powerful contractions of its muscular mantle to escape. These squids feeds mainly in day time at deep water layers (400-600m) on concentrations of nonactive midwater fishes. The behavior of T. rhombus leads to a decreased energy consumption in the costs of active metabolism, enabling the squid to maintain very high growth rates. Age and growth of T.rhombus has been studied by analysis of micro-growth increments. Life span has been estimated to be about one year , and males and females mature at age 6 -8 months. T. rhombus is one of the fastest growing squids: by the age of 300 days, they reach 750-800 mm ML and 17-17.5 kg of body weight (BW) T.rhombus has high potential fecundity (up to 4.8 million oocytes), but the maximum volume of oviducts is small (up to 140 thousand eggs) and so are the egg masses (35-75 thousand eggs). It is suggested that T.rhombus is an intermittent spawner with multiple filling and evacuation of oviducts.T. rhombus is characterized by low population density. It appears to have a unique social organization for squid: they live in pairs consisting a male and female of the same size from immaturity until death. These reproductive and behavioral strategies may be an adaptation to low population density and inactive life style. |
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