Terminal spawning in the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae)

Abstract

Maturation in the onychoteuthid squid Moroteuthis ingens was found to be irreversible, with death following shortly after sexual maturation and spawning. Both males and females were found with spent gonads. The ovary reaches very large sizes in mature females and probably prevents feeding by constricting the caecum. There was also a marked difference in the tissue integrity between immature females and females which had reached sexual maturity. Mature and spent females showed advanced tissue breakdown with individuals having a thin mantle wall with an inelastic, gelatinous appearance. Histological examination of the mantle wall revealed that the tissue breakdown was due to a drastic histolysis of muscle tissue and, to a lesser extent, collagen fibres. Mature males also showed some tissue breakdown and loss of muscle fibres but this was not as dramatic as in the females. These features are considered in relation to processes contributing to terminal maturation in M. ingens.

Diet of the squid Moroteuthis ingens (Teuthoidea: Onychoteuthidae) in the upper slope waters of the Kerguelen Islands

“…They were weighed and measured (dorsal mantle length, DML). Squids were allocated a maturation stage according to Jackson & Mladenov (1994). Of the 87 individuals, 52 were males and 35 were females.…”

“…Unlike other onychoteuthids, its occurrence and abundance at the bottom in the lower sublittoral and bathyal make M. ingens a bycatch in commercial and research trawling (Jackson et al 1998a(Jackson et al , 2000b, which has contributed to studies on its biology. Studies in New Zealand have demonstrated that the species is annual, undergoes an ontogenic migration from pelagic to benthopelagic waters and is a terminal spawner (Jackson 1993, 1997, Jackson & Mladenov 1994. Analysis of stomach contents showed that large individuals of M. ingens are primarily piscivorous, feeding mainly on mesopelagic fish in New Zealand waters and at Macquarie Island (Jackson et al 1998b, Phillips et al 2001.…”

Growth and reproduction of the squid Illex coindetii Verany, 1839 in the central Mediterranean Sea

“…Jackson & Mladenov (1994) suggested that there is likely a continuum of reproductive strategies among cephalopods from single spawning to multiple spawning species. Rocha et al (2001) described I. coindetii as an intermittent terminal spawning species, with behaviour more similar to a multiple than to a single spawning species.…”

Spawning cycle of onychoteuthid squids in the southern Indian Ocean:new information from seabird predators

“…The only possible explanations for this discrepancy are, first, that mating/spawning takes place at the surface, or, second, that after copulation and spawning at deep depths, incapacitated and dying squids rise to the epipelagic. The second hypothesis is most likely to occur because onychoteuthid squids are true terminal spawners, mature and spent individuals showing advanced tissue breakdown, and some of them, including Kondakovia longimana, having been observed floating dead or dying at the sea-surface (Clarke 1980, Jackson & Mladenov 1994, Lu & Williams 1994, Vacchi et al 1994. Arkhipkin & Nigmatullin 1997, Bello 1998.…”