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Not one, but 2 new Australian shark species have recently been described by CSIRO scientists and both have pretty cool appearances!

Long, thin, dark, catshark with a pointy nose.
Look at those haunting white eyes
Credit: CSIRO Australian National Fish Collection

CSIRO researchers Will White and Helen O’Neill lead the team of scientists who introduced the world to these new sharks, both found in deeper waters off north-western Australia.

The CSIRO team first published the ridged-egg catshark (Apristurus ovicorrugatus), which they found 300 kilometres west of Broome at depths over 400 metres. Its most recognisable feature is its unusually bright white eyes.

Orange coloured, ridged sack with two long strands on either side of the opening
Scientists don’t yet know what purpose the ridges serve
Credit: CSIRO Australian National Fish Collection

As you might have guessed from their name, these sharks lay eggs with distinctive ridges. They lay these eggs and attach them to branching corals to stop them from drifting away. It was the unique ridged eggs that first alerted Helen and Will to this new shark species. The eggs of all other Australian demon catsharks (genus Apristurus) have smooth egg cases.

“The egg cases of sharks are amazing to study – they come in a variety of different shapes, colours and sizes. It’s been really fascinating to match up what eggs belong to what species and to learn about the function of different structures,” says Helen.

Twisted brown shark egg with tangled string like tendrils on one end.
The sharks wrap the stringy tendrils around coral to keep the eggs in place
Credit: CSIRO Australian National Fish Collection
Small striped shark from above and the side.
The painted hornshark holotype specimen
Credit: CSIRO Australian National Fish Collection

The second shark to be described was the painted hornshark (Heterodontus marshallae). Previously thought to be zebra bullhead sharks (Heterodontus zebra), due to their very similar skin patterns. But once Will and Helen compared genetics, appearance and egg cases, they determined that the sharks were actually 2 different species.

Painted hornsharks are found only off north-western Australia at depths of 125 to 230 metres and they have an unusual set of teeth. The front of their mouth has shark-like teeth, while the back has rows of human-like molars to crush their hard-shelled prey!

New species need a holotype – the specimen from which the species can be formally described. Fortunately, at the end of 2022, while Will and Helen were surveying Western Australia’s Gascoyne Marine Park, they collected a 54-centimetre male. This male was in perfect condition, allowing it to become the painted hornshark holotype. This will support future research on this new, unusual shark.

 

 

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