The female reproductive cycle of the octopus,Eledone cirrhosa

Abstract

Changes in the relative size of the ovary, oviducal glands and eggs are described forEledone cirrhosacaptured from the North Sea off Aberdeen over a 3 year period(N= 488). The analysis is based only on freshly caught animals, excluding those held in aquarium conditions (> 5 days). Ovary enlargement and egg size estimates are used as indices of sexual maturity. Between 0–15% and 18–95% of total body weight is contributed by the ovary. Maximum egg length in the ovary ranges up to 7 mm. On these criteria, sexual maturation typically occurs at body sizes between 400–1000 g although some animals of 1000–1200 g are found showing no evidence of ovary enlargement. The majority of the monthly sample is always immature but maturation can apparently occur at almost any time of the year. Increase in mean ovary index and mean values for egg size are strongly seasonal and indicate a peak incidence of sexual maturity over 2–3 months in the July-September period. Spawning is presumed to follow within 1 month. Estimates of the fecundity of the females, based on the egg sample from the ovary, range from 2·2 × 103 to 55 × 10 3 eggs with a mean of 11 × 10 3 and a mode of 7·5 × 10 3 eggs.

Determination of age and growth of the horned octopus <em>Eledone cirrhosa</em> (Cephalopoda: Octopoda) using stylet increment analysis

“…The reproductive peak in the western Mediterranean, at a similar latitude to the above-mentioned study, is similarly timed (Lefkaditou and Papaconstantinou 1995, Mangold-Wirz 1963, Moriyasu 1988. However, studies performed in Scotland indicate that egg-laying occurs later, between July and September (Boyle and Knobloch 1983), suggesting that latitude, through day-night duration, is an important parameter influencing sexual maturation (Regueira et al 2013).…”

Male reproductive maturity in the octopus,Eledone cirrhosa(Cephalopoda: Octopoda)

“…The absolute collective size of the reproductive organs increases throughout life and, if the storage of spermatophores in the spermatophoric sac is an indication that the animal is sexually mature, we presume that the male is capable of insemination at sizes from about 200 g upwards. The male appears to be reproductively active over a significant proportion of its adult life; a contrast to the female, which may be quite immature at large body sizes and which probably matures over a period of a few weeks for a short period of egg-laying (Boyle & Knobloch, 1983).…”

“…It is known that females of this species can store sperm in the ovary (Boyle & Knobloch, 1983;Mangold et al 1971). In this feature E. cirrhosa differs markedly from O. vulgaris, where sperm introduced into the female lodges in the oviducal glands (Froesch & Marthy, 1975).…”

“…Methods for their capture and maintenance have been published elsewhere (Boyle, 1981), and the sample described here was obtained as part of a general study of growth and feeding in this species (Boyle & Knobloch, 19826). The female reproductive cycle in the population has been described (Boyle & Knobloch, 1983) and some aspects of male maturation were included in Boyle & Knobloch (1982a).…”

Reproductive status of opisthoteuthis sp. over an annual, cycle

“…is very low in comparison with that of other octopods, with an overall mean of 2.88% and a maximum of 7%. The GSI of incirrate octopods such as Eledone cirrhosa may reach almost 19% in the field (Boyle and Knobloch 1983) and <36% under aquarium conditions (Boyle and Knobloch 1984). The comparatively small GSI in Opisthoteuthis sp.…”