Citizen scientists find rare crab, spectacular anemone off WA's Kimberley coast

A crab that has only been documented a handful of times around the world has been found off the West Australian coast for the first time.

Sharmaine Donnelly-Chorlton said she was doing a regular wander at a rocky subtidal reef at Entrance Point in Broome when she spotted the odd creature.

"When I saw these two crabs I was very intrigued, as I hadn't seen them before," she said. 

Western Australian Museum crustacean and worms curator Andrew Hosie said it was "quite a mystery" when he could not identify the species.

"Mentally going through the list of crabs that are in my head for what I know was in the area … it just didn't quite match," he said. 

Dr Hosie said he began an extensive search because he disliked "not being able to finish a quest".

By studying photographs he identified the species as Rathbunaria orientalis.

"We haven't seen it in WA before," Dr Hosie said.

He said very little was known about the crab, but it was "certainly not something that's just crawling around on every rock".

The welfare of marine life near Entrance Point has been a focus in recent years ahead of planned development in the area.

Not the first rare sighting

Nearby in Broome, resident Dianne Bennett made another rare sighting.

She was walking at the Reddell Beach side of Entrance Point last week when she came across a creature in the sand she had never seen before.

"My first thought was, 'There's a weird bunch of eels going down a hole,'" Ms Bennett said.

The Medusa-like creature was identified as an armed anemone.

WA Museum marine invertebrate curator Zoe Richards said the "spectacular" anemone was rare to see but was on occasion also found in Queensland.

"I think I've only seen it one time on my surveys," she said.

"It can occur in the mangroves and all the way out across the sand, in the mud, and onto the reef itself.

The species uses a neurotoxin to switch off electric currents between their prey's cells, which affects the nervous system.

"This can lead muscles to go into paralysis and basically stops the communication between the cells," Dr Richards said.

This is how the toxin is working inside the body of the crab, but also inside human's cells."

An untouched landscape

Ms Bennett said there was likely a significant amount of undiscovered species along Australia's coastal landscapes. 

"The marine environment is like another world, you never know what you're going to stumble across," she said.

To find out more and fully confirm the species of the crab, Dr Hosie said the next step would be to obtain a specimen.

He said there were species waiting to be discovered across WA.

"Broome would be a very good starting point for anyone wanting to find them," Dr Hosie said.