Dolphins

A genetic scientist managed to create dolphins that would live to 250 years of age - if they were fed seagulls. One day the scientist's supply of gulls ran out, so he went out to trap some more. On the way back, he came upon two sleeping lions. Not wanting to wake the big cats, he gingerly stepped over them and was promptly arrested for... Transporting gulls across sedate lions for immortal porpoises!