While spending the day in Australia's Port Hacking, New South Wales local Luke Anslow happened upon a rare find. A small shark had washed up on the beach – and a closer look revealed the creature was completely colourless.
Initial reports suggested the animal was an albino salmon, mako or porbeagle shark, but allow us to set the record straight: what you're looking at is a leucistic great white shark pup.
Though the term leucistic is often used interchangeably with "partially albino," the two conditions are quite different. Unlike albinism, which causes a complete lack of melanin throughout the body, leucism doesn't affect the eyes. Had this animal been a true albino, the eyes would have appeared red or purple, rather than the typical inky black. In fact, most reports of "albino" animals fall into this category.
The shark showed no obvious signs of injury, but the local fisheries department hopes further analysis of the body will shed some light on what caused the animal to strand. "it was thrashing around in the shallows, before it ended up on the beach," recalls Anslow. "I wouldn't go near it, but I was there to take the photos."
Little is known about the early lives of great white sharks. As with most ocean giants, we're only just beginning to figure out the whereabouts of their pupping grounds. So seeing a baby – let alone such a distinctive one – is certainly cause for excitement.
"It is not a salmon shark," explains shark biologist Dr Alison Kock. "They are found only in the Northern Hemisphere. So that leaves white shark pup, or a juvenile mako or porbeagle."
Though the colourless shark's snout is too blunt for a mako, juvenile white sharks do look an awful lot like the much smaller porbeagle sharks. So, how do we get a precise ID? Massachusetts Shark Research Program biologist John Chisholm explains there is one clear giveaway: the caudal keel, a ridge found just forward of the tail fin.
"From the pictures I've seen online I'm confident it's a white shark, but I understand the confusion," he says. "Juvenile white sharks are very similar in appearance to porbeagles. The easy way to tell the difference is the porbeagle has a secondary caudal keel and the white does not. You can see an example of this secondary keel in one of my old tweets:
Because the Port Hacking shark has only one caudal keel, its great white identity is a sure bet (though a thorough analysis of the shark's teeth would confirm this with greater certainty).
This isn't the first time we've seen a leucistic shark pop up in the news. Back in 2000, fisherman Brian Cantrell managed to catch and release a partially albino blacktip shark off the coast of Texas (photos below). But a great white? That's one for the books. We'll be updating you as information from the necropsy comes in, so watch this space!
Top header image: David Remsen/Flickr