It is not known how the 20ft whale died

The whale was first found at a beach on the Lizard on 11 February. Researchers were able to take measurements and samples for scientific research.

But before they could examine its lower right hand jaw it was washed out again.

The Cornwall Wildlife Trust said it was not known how the 6.2m (20ft) long whale died. Anyone who finds it washed up again is asked to call the trust.

Official recorder

Jan Loveridge, one of the trust's Marine Strandings Network's coordinators, said: "When we were first called out, we assumed it would be a minke whale.

"We couldn't believe that what we actually had was a very young fin whale which, at that length, could have only recently been born.

"The last fin whale we had in 2004 was over 15m long and they can grow up to 22m."

Mrs Loveridge said the volunteers were fully expecting the whale to wash up again the day after they examined it but, so far, it has not done so.

She said: "We went back the next day to see if it had rolled over so we could examine the other side.

"But, to our surprise, it had washed out on the tide despite being wedged behind a large rock.

"We really want to get a look at the lower right hand jaw as this is a distinctive feature in fin whales."

Fin whales are toothless, filter-feeders which feed on small fish, squid and crustaceans.