Antiopi, a loggerhead, was rescued by the sanctuary in the 1990s after she suffered a gaping head wound off the Greek coast.
The brain-damaged reptile could not be released back into the wild, and Scarborough staff took her from a research facility in Athens and gave her a loving home.
But now a collaboration with the Royal Veterinary College in London has seen Antiopi receive a CT scan which revealed the full extent of her injuries - as well as a surprise.
“It confirmed that Antiopi suffered major damage to the hind part of her brain, from either a collision with a boat or a deliberate blow from an unsympathetic fisherman,” said displays supervisor Lyndsey Crawford.
“The neurological tests also suggested a corresponding lack of sensation down the left hand side of her body.”
Antiopi appeared otherwise to be in good health, but there was a surprise for Lyndsey and her team when the scan also revealed that she is carrying eggs.
“She doesn’t have a mate, and the eggs will not be fertile, but it was really useful to know she’s carrying eggs.
“We have built a haul-out ramp and a small beach at the top of her tank so she can lay the eggs, and can now watch out for signs she is ready to do this and make sure she is not disturbed when the time comes.
“We drove her down to London and back again in a specially built transport box and she seemed pretty relaxed the whole time,” Lyndsey added.
Antiopi is now back in her ocean tank preparing for the arrival of her clutch of eggs.
Another Sea Life Centre attraction, at Weymouth in Dorset, is also taking part in the project, allowing their green sea turtles who have had their spines severed in collisions with boats in the Florida Keys to be scanned.
“The RVC’s support should help us tailor the care we provide for all our rescued sea turtles to ensure we give them the best quality of life possible.”