Harvest whale

The Harvest Whale was a marine animal native to the planet Harvest.

It is rather more eel-like in appearance than normal Earth whales, and is unlikely to be a direct relative of Earth's mammalian variants.

When Harvest was glassed, the Human population suffered tremendous loss, but the natural environment fared worse. The entire ecosystem was turned toxic, leading many native species to die off. The Harvest Whales suffered such a fate.

A dead, beached whale can be seen in the concept art for Halo Wars.