It is more eel-like in appearance than Earth whales, and is unlikely to be related to Earth's mammalian variants.
When Harvest was glassed, the human population suffered tremendous losses, and the natural environment fared little better. The entire ecosystem was turned to a toxic environment, leading many native species to die off because of the toxic air. The Harvest Whales suffered such a fate. The fate of the Harvest Whales and the animals on the planet Harvest is unknown, though most likely died or became extinct due to the environment.