Tentacle tales

PhD student Peter Morse with a deadly blue-ringed octopus. Picture: Andrew Ritchie d421378
PhD student Peter Morse with a deadly blue-ringed octopus. Picture: Andrew Ritchie d421378

‘Essentially, it’s studying the population distribution and genetic structure of the southern blue ring octopus because it’s an animal we know virtually nothing about,’ Mr Morse (28) said.

The third-year James Cook University doctorate student has been working out of UWA.

His traps, hidden under small black buoys near rock reefs, caught none of the cephalopods |at the Dutch Inn break about 1km south of Cottesloe but the |creatures were found on open seabed, possibly providing some of the only shelter for the small octopus.

Traps were also set off Marmion, Hillarys, Rockingham, South Fremantle, with about 110 animals caught in Cockburn Sound found to be closely related.

Mr Morse obtained other genetic samples between his catches by recruiting commercial fishermen.

They contributed 90 per cent of about 200 animals caught between Albany to Dongara since January that were used in his research.

A genetic map of the species along the WA coast may show if there are sub-species, whether development such as dredging or marinas could interfere with mating, how newborn octopuses reach new coast, and if distinct groups exist.

‘In Albany we were getting them in one bay where they were huge, about the size of your fist, whereas in another bay they were about 3cm at the largest,’ Mr Morse said.

It is possible the short life of the blue-ringed octopus ” thought to last seven months ” could play a part in producing the genetic differences by expediting many generations over a short time span.

‘And they go out with a bang, with the males spending the last one to two months of their lives breeding furiously and the females guarding eggs, before they die a few weeks after the eggs hatch,’ Mr Morse said.

He will analyse the samples at laboratories in Queensland.

‘I suspect not many people see them in WA because they are nocturnal,’ Mr Morse said.

‘Preliminary findings during laboratory observations show octopus spend most of the day hiding under rock shelves, coming out at night to find food and mates.’