While resting by a river, Team Avatar encountered a platypus bear thrashing at a man from Makapu Village, though he nimbly managed to avoid all of its blows. Aang intervened, and Appa frightened the creature from behind with a loud roar. Terrified, the platypus bear laid an egg and fled.
During the spring of 100 ASC, a Fire Nation circus owned two platypus bears, one of which was a cub. One day, the circus directors were struggling to get the full-grown platypus bear to move, though when it did, the bear laid an egg. Weeks later, Appa was brought to the circus and confined in a cage near the platypus bear.
Team Avatar had their second run-in with a platypus bear at the Full Moon Bay ferry terminal, where one was kept by the guards to dispose of contraband vegetables, especially those infected with cabbage slugs. When the cabbage merchant's crops were denied entrance into the city, the guards let the platypus bear destroy all the cabbages. After the passport attendant noticed Momo, she threatened to call security again to have them "dispose" of the animal. Momo cowered away upon viewing the frightening platypus bear.
In Ba Sing Se, when Katara read that the Earth King Kuei was hosting a party for his bear, Aang guessed it might have meant a platypus bear. Later, one was accidentally set loose and chased citizens of the city before Aang created a new zoo.
The platypus bear's fur is mostly brown with a white "V" on its chest similar to that of a sloth bear, and a patch of lighter brown around its eyes. The creature has a large bill lined with jagged teeth and a platypus-like tail. Its front paws are padded with claws and it has large, webbed hind feet.
This animal is quite vicious, and is known to attack humans. When they do attack, they use their clawed paws, as well as their rudder-like tail which also helps them swim. This is an even more likely occurrence when a baby platypus bear is involved; a mother platypus bear is very protective of her young. However, they can also be trained and domesticated.
The platypus bear is capable of standing upright and also lays eggs, rather than giving birth to live young. These eggs often seem to be laid involuntarily when the platypus bear is in a heightened state of emotion, such as fear or anger. The platypus bear can also be trained and has been seen as both a circus animal and a brute enforcer.
As the name implies, this animal is a cross between a platypus and a bear, sharing many characteristics with both namesakes.
- Decades after the Hundred Year War, a pro-bending team named itself the Pinnacle Palace Platypus Bears.
- During the Invasion of the Fire Nation, Azula proved to Toph that she was a good liar by describing herself as a "four hundred foot tall purple platypus bear with pink horns and silver wings".
- Platypus bears seem to have the ability to lay an egg at almost any moment. Twice in the show, a platypus bear laid an egg at a random moment in time, while showing no signs of needing to beforehand.