Cephalopod Biology

Abstract

Since 1983, when Caddy was able to state that ' ... except in a few ocean regions, they (cephalopods) are not subject to exploitation', the decline in many fmfish stocks has led to increased attention on other groups such as cephalopods, the increasing economic importance of which is evidenced by the rapid rise in their global landings over recent decades. World cephalopod landings (capture fisheries) rose from 500,000 t in 1950 to a peak of more than 4 million t in 2007, with landings increasing in most regions with the exception of the Northeast Atlantic. New regions such as the Southwest Atlantic and the Southeast Pacific subsequently became important cephalopod fishery areas, supplying new abundant species to worldmarkets (notably Illex argentinus and Dosidicus gigas). In Europe, the potential expansion of cephalopod fishing will require a new focus on monitoring, assessment and management of these fisheries, taking into account the differences in life history between cephalopods and fish. The increasing demand for cephalopods on the intemational markets has stimulated research on rearing and 'ongrowing' of cephalopods (mainly common octopus) as an altemative to reliance on fisheries.

Cuttlefish can school in the field

“…supposed to be older member) forming large schools. Therefore, Sepiidae might have particularly strong social relationships during young and reproductive stages, although they have the tendency to spend time alone as subadults, characterized by an adult-like external morphometry even though they are not sexually mature (Boletzky and Villanueva 2014).…”

“…Based on the videos, we estimated the dorsal mantle length (ML), sex, and maturity (Boletzky and Villanueva 2014). Sex and maturity were determined by body colouration [males with closely set irregular transverse lines exhibited on mantle and fin; females with no transverse lines exhibited on body but elongated iridescent spots exhibited on the fin, female body appears to be more translucent than males (Corner and Moore 1980)], and mating behaviours.…”

Composition and metabolism of phospholipids in Octopus vulgaris and Sepia officinalis hatchlings

“…In fish, PLA 2 activity tends to increase during development, with seabream and sea bass larvae showing no PLA 2 activity during very early larval stages (Izquierdo and Henderson, 1998;Zambonino Infante and Cahu, 2001). Both octopus and cuttlefish possess inner yolk reserves that could last for a few days after hatching (Sykes et al, 2004;Boletzky and Villanueva, 2014) and it is known that it can take up to 30 days for the digestive system to fully mature in cuttlefish (Boucaud-Camou and Yim 1980;Yim and Boucaud-Camou 1980;Boucaud-Camou 1982). Nonetheless, these species may feed on size-appropriate prey from day 1 (Hanlon and Messenger, 1988), when mixed feeding overlaps inner yolk reserves and external food consumption (Boletzky, 1974;Sykes et al, 2013).…”

A practical staging atlas to study embryonic development ofOctopus vulgarisunder controlled laboratory conditions

“…At Stage IX, the arm buds are clearly separated from one another, the mantle appears more elevated and first yellow pigmentation of the retina is visible. The yolk sac envelope that contains blood lacuna and a network of muscular elements starts to create peristaltic waves of surface contraction at this stage, establishing blood circulation for the early embryo (Additional file 14 shows yolk contraction at Stage XI) (34). This phenomenon will cease around Stage XVI, when the embryonic heartbeat is well established and when the area of contact between the yolk envelope and the chorion becomes too small (12).…”