Age and growth of planktonic squids Cranchia scabra and Liocranchia reinhardti (Cephalopoda, Cranchiidae) in epipelagic waters of the central-east Atlantic

Author： Arkhipkin Alexander

Publisher： Oxford University Press

ISSN： 1464-3774

Source： Journal of Plankton Research, Vol.18, Iss.9, 1996-01, pp. : 1675-1683

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Statolith microstructure was studied in two abundant planktonic cranchiids, Cranchia scabra (56 specimens, 38–127 mm mantle length, ML) and Liocranchia reinhardti (34 specimens, 99–205 mm ML) sampled in epipelagic waters of the western part of the Gulf of Guinea (tropical Atlantic). Growth increments were revealed in ground statoliths of both species. It was possible to distinguish two growth zones in statolith microstructure by their colour in reflected light of the microscope: the translucent postnuclear zone and pale white opaque zone. Assuming that growth increments in statoliths were produced daily, ages of the largest immature C.scabra and L.reinhardti were 166 and 146 days, respectively. Both cranchiids are fast-growing squids with growth rates in length resembling those of juveniles of tropical ommastrephids and Thysanoteuthis rhombus. Liocranchia reinhardti grows faster: its growth rate in ML is approximately twice that of same-aged C.scabra. The life cycle of both cranchiids consists of two phases. During their epipelagic phase, C.scabra and L.reinhardti feed and grow rapidly from paralarvae to immature young in the epipelagic waters, attaining 120–130 and 170–200 mm ML by ages of 4–5 months, respectively. Then they change their life style to a deepwater phase.