The Beasts-of-Burden resemble a hybrid of a large bear and a giant sloth, except that they have a green coat. They run preferably on all fours, the front legs are on the outside of their inwardly curved claws and supported with raised shoulders, with which they are on average 2.50 meters high. (In a completely upright posture they would probably reach a standing height of at least 3.50 meters, although it is not known whether this species is capable of this). They are vegetarian and seem to particularly like nuts.
Cartoon Series (2003)
The Beasts-of-Burden were originally people who more than ten thousand years ago were enslaved by the Y'Lyntians and turned into monsters in order to maintain their decadent lifestyle. However after a time living as slaves the other human cultures banded together to destroy Atlantis. The Y'Lyntians used their sun crystal to annihilate the human fleets. But the Beasts-of-Burden were allied with the humans and redirected the Sun Crystal's energies back at it, sinking Atlantis to the bottom of the sea. This was revealed in the episode The Entity Below.
Somehow some of the Beasts-of-Burden managed to escape, onto the nearby mainland where they have since eked out an existence in the primeval forests. The Beasts-of-Burden came up in occasional sightings in oblivion and became mythical creatures, but a few managed to survive in the woods until the modern era. The Beasts-of-Burden made their first appearance in the episode The Monster Hunter, where one was hunted by Abigail Finn. One of their females randomly met Michelangelo, Donatello and Casey Jones in the woods of Northampton near the Jones Farm, who then helped her to slip through the cracks, of the possessed monster hunter Abigail Finn. At the end of the episode, it was revealed this was a mother with several children. The current status of the species is not known.