NANFA-- octopus life spans
Fri, 12 Mar 2004 16:26:39 EST

I asked the ceph list about the octopus life spans and here is what I got

Hello Moon:

The male giant Pacific octopus may live for a much as 5 years but that is not
yet proven. My research was able to follow both sexes up to a body weight of
about 15 - 18 kg (33 - 40 lb) and at that point they are about 32 months of
age. Sexually mature, the females mate, build a nesting site, lay their eggs
and then brood the eggs for 6 - 8 months. At that point the females die having
lost more than 50% of their body weight. Age is approximately 3 years old
plus a few months.

The males at sexual maturity become very mobile and difficult to track.
Judging from the fact that males are often found weighing 30 kg (66 lb) or more
they have continued to feed. What I don't know is what the growth rate curve
looks like after they reach sexual maturity. If they are doubling their body
weight every 120 days (which is what is happening near sexual maturity) then to
go from 15 kg to 30 kg would only take another 120 day (4 months). If that's
the case the males would not live much longer than the females. If the growth
rate is slower (as I strongly suspect it is) than the males are older but not
by much as I seldom find animals in excess of 45 kg (99 lb). My best guess
is that the males are less than 4 years old when they die.

Other species may be longer lived but I don't know of any strong evidence to
support that.



James A. Cosgrove, M.Sc.
Manager, Natural History Section
Royal British Columbia Museum
675 Belleville Street
Victoria, B.C.
V8W 9W2
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