NW dolphins throw sponges to attract mates

Diamonds might be a girl’s best friend, but it appears the North West’s male humpback dolphin population believes marine sponges are the way to a female dolphin’s heart.

UWA, University of Zurich and Murdoch University researchers off the North West coast captured the bizarre sexual display, where males were presenting the sponges to female dolphins.

They documented adult male Australian humpback dolphins presenting large marine sponges to females, as well as performing visual and acoustic displays.

The use of objects in sexual displays by non-human mammals is rare and the researchers say it could be a display of the male’s quality as a mating partner.

UWA school of biological sciences lead author Simon Allen said the findings suggested an unrecognised level of social complexity in humpback dolphins.

“We were at first perplexed to witness these intriguing behavioural displays by male humpback dolphins, but as we undertook successive field trips over the years, the evidence mounted,” he said.

“Here we have some of the most socially complex animals on the planet using sponges, not as a foraging tool, but as a gift, a display of his quality, or perhaps even as a threat in the behavioural contexts of socialising and mating.”

Co-author Stephanie King said some adult male dolphins appeared to be working in pairs.

“The formation of alliances between adult males for the purposes of coercing females is uncommon, since mating success cannot be shared,” she said.

“This is a new finding for this species, and presents an exciting avenue for future research.”

Researchers hope to determine whether or not presenting sponges and engaging in sexual displays improves an individual’s chance of mating success.