Thousands of toxic jellies have been washed up at a popular beach on the NSW far south coast, triggering curiosity and a warning to pet owners.
Sea hares, which are a type of sea slug, began washing up at Aslings Beach at Eden a week ago.
Macquarie University marine biologist Culum Brown said it was no coincidence they arrived alongside a naturally occurring algal bloom.
"They graze on algae," he said.
"The danger here is that some of the algae they eat contain various toxins which the slug can maintain and use as a predator defence."
Thousands of sea hares were first spotted at Aslings Beach on Tuesday, October 13. (Supplied: Bega Valley Shire Council)
High tides caused many of the toxic sea hares to disperse back into the water.
The Bega Valley Shire Council also organised local contractors to remove them from the beach.
However, some still remain in patches along the shore, causing intrigue among beach goers.
"When they're underwater, they have protrusions that look a bit like the ears of a rabbit or a hare," Professor Brown said.
"They produce an ink-like excretion when they're alarmed, a bit like squid."
The tides and council clean-up efforts have reduced the number of sea hares at Aslings Beach. (ABC South East NSW: Adriane Reardon)
Toxic and slimy
The algae itself was identified by the Bega Valley Shire Council (BVSC) as a mix of red macroalgae native to south-eastern Australia and non-toxic.
But sea hares feeding on the algae can pose a serious risk to dogs if they lick, mouth or ingest them.
Pet owners visiting the beach are advised to keep a distance.
“Council crews removed thousands of sea hares from Aslings Beach last week," BVSC sustainability manager Derek Van Bracht said.
"The volume of sea hares on the beach has since reduced, however a visible algal bloom remains offshore.
"So dog owners are advised to stay vigilant when walking their pets in the area."
The algal bloom at Eden, photographed on October 9. (Supplied: Joanne Korner)
Professor Brown said although sea hares were a bit "odd looking", it was not unusual to see them wash ashore in large numbers on the southern-Australian coastline.
He said their arrival usually coincided with rough seas and strong on-shore winds.
Professor Brown said while sea hares were not dangerous to humans, precautions should still be taken.
"If you do handle them, you should definitely wash your hands," he said.
"Don't touch your eyes, because they can cause irritation."
Dozens of sea hares are still appearing at Aslings Beach. (ABC South East NSW: Adriane Reardon)