AN EAGLE-eyed teenager spotted an unusual river inhabitant.

Jonathan Raiseborough, 17, was walking home after a visit to South Park in Darlington when his 13-year-old sister Hannah spotted what appeared to be a tortoise by the side of the River Skerne.

The teenager did not believe his sister at first but when he used his camera to zoom in on the creature, the photographs he took show that it could be a tortoise or a terrapin.

He said: “It did look very wet so it had been in the river, but I’m pretty sure that tortoises don’t live there naturally.”

Jonathan suggested that the tortoise was an escaped pet.

He spotted it on the river embankment by the South Park entrance gates at the end of Victoria Embankment.

Tortoises are not native to the UK but are relatively popular as pets.

Their popularity led to a ban on importing 18 species from Mediterranean, African and Eurasian countries in 1999, meaning that only captive-bred tortoises or those imported before the ban are allowed to be sold as pets in this country.

Terrapins, meanwhile, have been a feature of UK waterways since the 1980s when many people bought them as pets after being inspired by the popular Teenage Mutant Ninja Turtles cartoon.

When they got too large, they were often dumped in rivers and streams.

Terrapins can live up to 40 years in the wild, living on frogs, fish, and even ducklings, and it is not uncommon to see them swimming or basking in Britain's waterways during hot weather.