The gripe is a large (3-4 meters) aquatic rodent distantly related to the coypu and the voorngk. The gripe inhabits shipyards, wharves, and brackish marshes on the eastern coast of South America and in northern Michigan.

The gripe is nocturnal except during the daytime, when it forages for thistles, grape vines, and prebendaries. Its coat is long and thick, in heft and odor closely resembling that of the coypu. Its young are born live, but the condition seems not to be permanent. In mating season, the gripe will often impersonate the thrush with some success. Gripes are solitary, moody, and tedious.

There are two subspecies of gripe: The Greater and the Lesser. They are identical.