New Zealand Journal of Marine and Freshwater Research abstracts
First encounter with a live male blanket octopus: the world’s most sexually
size-dimorphic large animal
M. D. Norman1,2
D. Paul2
J. Finn3
T. Tregenza4
1Sciences, Museum Victoria
GPO Box 666E, Melbourne
Vic 3001, Australia
email: mnorman@unimelb.edu.au
2Department of Zoology
University of Melbourne
Vic 3010, Australia
3Institute of Antarctic and Southern Ocean Studies
University of Tasmania, Hobart
Tas 7000, Australia
4Ecology and Evolution Group
School of Biology, University of Leeds
Leeds, LS2 9JT, United Kingdom
email: T.Tregenza@leeds.ac.uk
Abstract The first encounter with a live male blanket octopus, Tremoctopus violaceus
Chiaie, 1830, illustrates the most extreme example of sexual size-dimorphism
in a non-microscopic animal. Females attain sizes of up to 2 m long-almost
2 orders of magnitude larger than the 2.4-cm-long male. Weight ratios between
the sexes are at least 10 000:1 and are likely to reach 40 000:1. Sexual
selection and the unique defensive strategy of carrying cnidarian stinging
tentacles may both have contributed to the evolution of this extreme size-dimorphism.
Such dimorphism is not seen in any other animal remotely as large.
Keywords blanket octopus; Tremoctopus; sexual dimorphism; evolution; defences; Physalia
M02017 Received 8 March 2002; accepted 24 June 2002; published 14 November
New Zealand Journal of Marine and Freshwater Research, 2002, Vol. 36: 733-736
0028-8330/02/3604-0733 $7.00 © The Royal Society of New Zealand 2002
PDF file of entire paper: Print-quality (353K) | screen-quality (57K)
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