An 'alien' sea creature caught off the coast of Mexico which had been baffling internet users has been identified as an albino swell shark. The shark was pulled on board by Jamie Rendon, who took pictures of it before releasing it back into the sea of the Cabo corridor.

He shared the images with Pisces Sportfishing Fleet, a local fishing and tourism business. The pink, bulbous shark was about two feet in length and had "raspy skin, three rows of tiny teeth and three gill slits on each side of the head", Rendon told the company.

Rendon, the captain of the Dr Pescado boat, said he had been fishing with a client about a mile off shore. "I was really surprised but what caused most impact were the eyes, so strange," he said.

He thought the shark might be an endangered species so released it back into the wild and sent images off to marine experts. A number of people said it looked like a swell shark, which can fill its stomach with water to make itself swell to about twice its normal size in order to avoid being swallowed by other sea predators.

Swell sharks are found in the Eastern Pacific, central California coast, the Gulf of California and the southern tip of Mexico. They are normally a greyish brown colour with black spots so the pinkish colour of the shark was unusual. As was its three gill slits – most sharks have five to seven gills on each side.

Eventually scientists confirmed it was a swell shark, but an albino variety: "Alien Fish Mystery Solved," Pisces Sportfishing Fleet wrote in a Facebook post. "After studying the photos the experts agree that the strange fish is an albino swell shark - still alive and well! Thanks Jaime for the great story and for releasing this cute critter."