A Queensland marine biologist has come face to face with a rare rainbow-like species of octopus while snorkelling off Lady Elliot Island on the Great Barrier Reef.
Sightings of the blanket octopus are so rare it is believed to have only been spotted three times in waters off the island.
This latest encounter takes that tally to four.
Marine biologist and reef guide Jacinta Shackleton has been conducting research and diving around Lady Elliot Island for almost four years.
"I was just out on a bit of a snorkel [on January 6], we were looking for some manta rays and turtles," she said.
"We came across what I thought was initially a juvenile fish, with some really long fins, but as it came closer, I saw it was really colourful, like a bright red and bright orange, and realised it was a blanket octopus.
She said the species generally spends its time in the open ocean, so to see it on the reef was "really special".
"This particular one had eye spots all over its blankets, which we think is a method to deter predators.
"I knew so little about them … I didn't even know whether it was a dangerous species, but I later learnt that it was, so it was lucky that we did keep a bit of distance.
"They're actually able to take stinging cells from other animals [like jellyfish] and then utilise those themselves.
"It was just really hard to take my eyes off it, it was so beautiful."
Male only spotted 21 years ago
Sightings of the species are so rare the first male was only spotted on the Ribbon Reefs, near Cairns, 21 years ago.
The species takes its name from the webbed cape or blanket that trails behind the female, a feature the males do not display.
Females of the species can grow up to two metres in size, while males only grow to about 2.4 centimetres in size, one of the largest gender size discrepancies in the marine world.
"It's quite unusual compared to a lot of species," Ms Shackleton said.
"The individual I saw, a female, she was also very small, maybe the size of a large walnut. That added to my initial confusion when I saw it, because it was so little.
According to the Great Barrier Reef Foundation, blanket octopuses are nomadic creatures that move to different locations every couple of days and can adapt to a variety of water temperatures.
They are carnivorous, with a diet consisting of mostly smaller fish.
Ms Shackleton said she was inspired to read research from Museums Victoria senior curator for marine invertebrates Julian Finn and colleagues after her encounter.
