Sea bears are a large piranha-like fish species with grizzly/Eurasian brown bear heads who are known for attacking. They come in brown, green, and a lighter green. They first appear in "The Camping Episode."
Squidward initially did not believe in the sea bear's existence, before he was attacked by one in this episode. However, SpongeBob and Patrick are fervent believers, having read about them in The Bikini Bottom Inquirer and Fake Science Monthly, which are both tabloid magazines. Squidward is mauled six times until he finally jumps into the dirt circle with the duo.
The sea bear appears again at the end, but seeing Squidward is now protected makes the sea bear leave the area, thus saving Squidward. The sound of a sea bear attack also attracts sea rhinoceros.
Patrick wonders where the RV is so he points to some growling sea bears. Squidward wants to protect SpongeBob and Patrick from them, thinking that they were attacking them. However, the sea bears were only playing tummy-tickle, which they like to do, although they don't like it when someone karate-chops their knee-highs, which Squidward just did, so sea bears attacked him.