Love in the octopus' garden

"If you're going to spend time guarding a female, you want to go for the biggest female you can find because she's going to produce more eggs," biology professor Roy Caldwell said. "It's basically an investment strategy."

Caldwell said he believes the behaviour is common to many of the nearly 300 species of octopus.

The animals usually mate several times a day once they reach sexual maturity. Males have a specially designed arm they use to deposit a sperm packet into the female, who retires to her den and lays tens of thousands of eggs.

Both parents die within a few months of mating, leaving the newborns to fend for themselves.

(Reporting by Maggie Fox)