Slug sex and species celebrated at Nudi Festival

Though they live for less than a year, the lives of nudibranchs are filled with lots of colour and uncomplicated, unconventional sex.

Nudibranchs – better known as sea slugs – are hermaphrodites and engage in copulation as both male and female, simultaneously impregnating each other.

They are also poisonous. The more colourful the nudibranch the more toxic it is.

This weekend (12-13 December) scuba divers from across Australia will converge on Port Stephens for the Nelson Bay Nudi Festival, which will incorporate the ninth Sea Slug Census.

The festival is a collaborative citizen science project celebrating the diversity and amazing body-forms of the colourful nudibranch. The shell-less, soft-bodied molluscs live on seabeds and are particularly abundant in shallow waters.

Festival co-organiser Associate Professor Steve Smith, from Southern Cross University’s National Marine Science Centre, said the weekend would be an opportunity to collect new scientific data about the butterflies of the sea.

“Nelson Bay is world renowned for the diversity of marine life at dive sites, and colourful nudibranchs are particularly abundant,” Professor Smith said.

“Divers travel from all over Australia and overseas to see and photograph them, so it’s a real opportunity to tap into this interest and gather some critical data at the same time.”

Professor Smith said there was no special formula to finding nudibranchs, ‘you just dive in and start looking’.

“There are 3000 known known species of sea slug with estimates at least another 2000 are yet to be discovered.

“In previous years we’ve found previously unrecorded species and introduced species of sea slugs that had extended their southern range on Australia’s east coast.

“Sea slugs have got very rapid life cycles and they can respond quickly to changing environments so they have great potential as indicators of environmental health.”

Divers participating in the festival will be in the running for the title of best nudi spotter, most unusual nudi spotted and for the best nudi photo and video.

Getting nudi – some sea slug facts:

- Nudibranchs have no shells and defend themselves by using borrowed toxins from their food sources.

- Nudibranchs are the most commonly photographed marine invertebrate.

- Most nudibranchs live for less than a year.

- Every nudibranch is a hermaphrodite and can mate with any other member of their species.

- There are about 3000 known species of nudibranch and at least another 2000 yet to be discovered.
Photo: The Goniobranchus Splendidus could be spotted at the Nelson Bay Nudi Festival.