A Prison Service spokeswoman said: "An incident at HMP Long Lartin on Thursday February 14 resulted in the death of prisoner Subhan Anwar.
"Two prisoners are now in police custody and the matter is being investigated by police."
More top news
The dolphin-like mammal was found between Hornsea and Bridlington. Six whales have also washed up on the East Yorkshire coast this year.
Olympic sprinter races RAF Red Arrows for new ITV show 'It’s Not Rocket Science'.
The afternoon weather update for Yorkshire and Lincolnshire with Jon Mitchell