Scientists have for the first time discovered the tiny baby larvae that grows into one of the world’s largest but most mysterious fishes.
The bump-head sunfish – which can grow to 2,000kg in weight and 3metres in length – are highly fertile and produce about 300million egg cells in a single season.
But it was not until a biologist at the Australian Museum Research Institute in Sydney extracted DNA from larvae found off the New South Wales coast last year that the link to the giant creature was finally made.
By taking genetic material from the eyeball of the 2mm-long larval specimen, molecular biologist Andrew King found a perfect match with an adult sunfish preserved at the museum.
The sample had been one of several collected by marine researchers in 2017 and sparked the curiosity of sunfish expert Dr Marianne Nyegaard – a researcher at the Auckland War Memorial Museum.
Dr Nyegaard said the link between baby and adult sunfish had been so difficult to make because the adult version looks nothing like their larvae.
She added it was even harder to do because sunfish larvae are not commonly found in the ocean.
‘If we want to protect these marine giants we need to understand their whole life history and that includes knowing what the larvae look like and where they occur,’ Dr Nygaard said.
‘This is the first time we have been able to genetically identify a Mola alexandrini larval specimen anywhere in the world.
A full-sized bumphead sunfish, known by the Latin genus mola alexandrini, is on display at the Australian Museum.
All three sunfish species – with the others being the ocean sunfish and the hoodwinker sunfish – can be found in Australian waters.
Their large dorsal fin and tendency to swim close to the water’s edge mean they are often mistaken for sharks.