From the size of a 50p coin to a dinner plate how terrapins spread across East Yorkshire

That's the conclusion of naturalists who have been out looking for terrapins in Hull and East Yorkshire's parks and ponds.

So far four species have been spotted in 32 locations including Hull’s East Park, Walkington village pond and Pocklington Canal.

Dr Africa Gómez, a Senior Lecturer in Biological Sciences at the University of Hull, said they sold in their millions in the 1990s, largely because of the Teenage Mutant Ninja Turtles craze.

People are spotting them more now - possibly because they’ve now grown to full size.

However they could eventually die out, as Yorkshire’s climate is not warm enough for their eggs to hatch.

It is also an offence to release them into the wild as they are regarded as non-native.

Dr Gómez said: "In the 90s when people were getting them at Hull Fair they were tiny like a 50p coin, the chances of seeing one was really minimal. When they get to dinner plate size they are hard to miss."

Terrapins are related to tortoises and sea turtles and can live to 40 years in the wild.

There have been releases into the wild since Victorian times, although the earliest definite record is at Brandesburton in 1992.

They've often been blamed for killing ducklings and waterbirds, but Dr Gomez said there was little evidence of this. And she said it wasn't fair to label them as invasive when they weren't even breeding.

She said: "Pike and gulls are likely to represent more serious predatory threats to chicks than terrapins. “However, we don’t know enough about the diet and ecological impacts of introduced terrapins, and this should be the focus of further research."