While resting by a river, Team Avatar encountered a platypus bear attacking a man from Makapu Village, though the man nimbly managed to avoid all of the bear's blows. Aang proceeded to intervene and attempted to placate the animal; his efforts had no effect, however, and Appa instead frightened the creature from behind with a loud roar. Terrified, the platypus bear laid an egg and fled.
During the spring of 100 AG, a Fire Nation circus owned two platypus bears, one of which was a cub. During Princess Azula's visit to the circus, the 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.
A platypus bear was among the animals that lived at the Ba Sing Se Zoo, though its conditions were poor and the animal itself was unhappy. Aang came across the zoo during his stay in Ba Sing Se, and seeing the poor conditions, endeavored to release the animals from their cages and move them to a more expansive zoo in the Agrarian Zone. However, after being released, the platypus bear began terrorizing the citizens of the city, causing mayhem along with the other animals. Upon hearing the signal from Aang's bison whistle, the platypus bear ceased its destruction and rushed with the other animals to follow the sound, eventually finding itself in the much larger zoo Aang had created outside the city walls.
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.
The platypus bear is quite vicious and is known to attack humans; when it does attack, it uses its clawed paws and its rudder-like tail, which also helps it swim. Platypus bear assaults are even more likely to occur when a baby platypus bear is involved, as a mother platypus bear is protective of her young. However, despite its wild nature, the platypus bear can also be trained and domesticated, having been used as both a circus animal and a brute enforcer and having been kept as a pet.
The platypus bear is capable of standing upright and also lays eggs, rather than giving birth to live young. These eggs can be laid involuntarily when the platypus bear is in a heightened state of emotion, such as fear or anger. The animal is usually found inland, swimming in rivers and hunting for its favorite food, the se tu fish.
As the name implies, this animal is a cross between a platypus and a bear, sharing many characteristics with both of its namesakes. In particular, the platypus bear has webbed feet, a bill, and the ability to lay eggs, much like the platypus, while also being bipedal and equipped with claws and sharp teeth, like a bear.
- Decades after the Hundred Year War, a pro-bending team named itself the Pinnacle Palace Platypus Bears.
- 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.
- In 171 AG, Varrick and Zhu Li hid inside a stuffed platypus bear named Ping-Ping in order to avoid being arrested by the Northern Water Tribe soldiers. Together, they were able to move the limbs of the animal in a way that made it appear as though it were alive.
- Following the premiere of The Adventures of Nuktuk: Hero of the South, Bolin used part of his earnings to buy a luxury platypus bear rug for his and Mako's apartment.