'Citizen scientists' track rare stingray

Recreational divers are helping scientists understand a rare stingray which has only been recorded 25 times in Australia since 1770.

The porcupine ray was first spotted by Europeans when Captain Cook's HMS Endeavour ran aground on the Great Barrier Reef.

Almost two and a half centuries later, photographs and video footage from "citizen scientists" are helping researchers know more about the elusive and mysterious stingray species, easily identified by its thorns and short tail.

"If you've seen one, consider yourself lucky," said Dr Andrew Chin, the lead researcher on a James Cook University study.

In 2012, scientists asked recreational divers to track the species via appeals in dive magazines, the internet, email lists and social media.

The pilot study doubled the number of records held in Australian museums and databases.

Dr Chin said scientists now know that the stingray lives on the Great Barrier Reef's southernmost coral cay, Lady Elliott Island, dives to a depth of 30 metres and lives in mangroves and mudflats.

The experts previously knew almost nothing about the animal's life cycle.

"It's potentially a very vulnerable species and this is why it's so important to fill in the information gaps," Dr Chin said.

"Scientists can't be everywhere at once.

"But when everyone in the community is 'on watch', we can get some really interesting information."

Climate change and habitat loss are considered the ray's biggest threats.

Video footage of foraging and mating behaviour was included in the study.

Divers also recorded a unique courtship between the porcupine ray being cleaned by a "cleaning wrasse".