An Australian scientist has described an invasive marine pest from New Zealand as the cane toad of the sea.
The New Zealand screwshell, which arrived in Tasmania 70 years ago in ballast water, has spread as far as Sydney Harbour, the ABC reports.
Scientists using a new remote-control underwater camera have for the first time revealed the extent of the invasion. They say it covers an area of the seabed the size of Tasmania.
Dr Neville Barrett, of the Tasmanian Aquaculture and Fisheries Institute, says the number of screwshells has grown dramatically and it is out-competing other species for space on the seabed.
"There's nothing that seems to be controlling it," he told the ABC. "It's a bit like the cane toad. It has a very, very tough and very, very thick shell."
It is feared that the pest will displace species like the scallop.