A sucker for sex life of oc­to­pus

Western Suburbs Weekly - - Street Watch - By JON BAS­SETT

MAS­TER­ING oc­to­puses’ sex lives is the fas­ci­nat­ing sub­ject of a study by Univer­sity of WA Ocean’s In­sti­tute­backed James Cook Univer­sity re­searcher Pe­ter Morse this sum­mer.

“We want to know just how the fe­males are choos­ing some males’ sperm over oth­ers, be­cause there are of­ten many fa­thers in any egg clutch,” Mr Morse (28) said.

Last sum­mer, his traps for the cephalopods along the WA coast, in­clud­ing Cottes­loe and South Fre­man­tle, con­trib­uted to re­sults pub­lished in the sci­ence jour­nal Be­hav­iour last month.

The ven­omous male south­ern blue-ringed oc­to­pus be­ing stud­ied is al­lo­cated about 50 sperm dur­ing its sev­en­month life.

Fe­males store dif­fer­ent males’ sperm in a gland be­hind their heads, be­fore po­ten­tially de­cid­ing which to use to fer­tilise pre­cious eggs, then they dig a bur­row or hide to pro­tect their young.

The moth­ers even­tu­ally die af­ter pro­tect­ing the eggs for two months, while the males die when they have ex­hausted their sperm.

“We also would like to know how the males seem to be aware of how much sperm the fe­males are hold­ing, and be­cause they have a lim­ited amount of sperm in a life­time they seem to be reg­u­lat­ing the amount they are us­ing,” Mr Morse said.

His pre­vi­ous stud­ies in­di­cated males ap­pear to be able to gauge just how much sperm from their com­peti­tors is be­ing held by the fe­males and males change the amount of sperm they leave with a fe­male, while en­sur­ing they have enough left for mat­ing with other fe­males.

“They ap­pear to strate­gi­cally al­lo­cate their lim­ited sperm,” Mr Morse said.

Last month, he started weekly col­lec­tions from about 200 oc­to­pus traps 50m-100m off­shore from the former South Fre­man­tle power sta­tion, near to where he trapped more than 110 an­i­mals in Cock­burn Sound a year ago.

”What we’re do­ing now is ver­i­fy­ing the be­hav­iour in­di­cated by our pre­vi­ous re­search that showed males mate to max­imise re­ten­tion of a lim­ited amount of sperm,” Mr Morse said.

Pic­ture: Marie Nirme www.com­mu­ni­typix.com.au d444981

Pe­ter Morse with two blue-ringed oc­to­puses col­lected.

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