A Museum fish curator has identified a skate's unusual appendage as an extra pelvic fin, rather than a genetic throwback to its shark relative.
An unusual skate has been caught by fishermen in the Solent with an extra fin.
It was taken to the Portsmouth Blue Reef Aquarium for identification, where it is now being held for safekeeping.
Aquarium staff have nicknamed it Elvis because the fin resembles a quiff.
Aquarium staff originally thought the extra appendage was a dorsal fin from a genetic throwback to a shark. Skate are distantly related to sharks.
On closer inspection, however, they realised it was more likely a bizarre mutation.
Natural History Museum fish curator James Maclaine, who was brought in to identify the fin, realised it was something entirely new.
'Mutated skates do turn up from time to time, sometimes with fin anomalies that make them heart-shaped, but we still have never seen anything quite like this one before,' Maclaine said.
'The general consensus is that it’s a mutation, and probably more likely an out of place extra pelvic fin rather than a new dorsal fin,' he said.
Elvis showing off the full extent of his quiff, a mutated fin.
Thornbacks are the most common skate in British waters and can grow up to 1.2 metres in length. Rays and skate are effectively flattened out versions of sharks.
Elvis appears to be in prime condition, so the fin doesn't seem to have hindered the ability to hunt.
The skate is being kept in a quarantine tank at the Portsmouth Blue Reef Aquarium until it's given the all-clear, after which it'll be on display to the public in an open-top tank.