A recent survey of the animal kingdom has found that, like humans, animals just wanna have fun. To anyone who's ever spent time with a dog, it may seem obvious that animals can enjoy play for the sake of it—though this hasn’t been so well documented in the scientific realm. Jonathan Balcombe, a research scientist with the Physicians Committee for Responsible Medicine, has now gathered a list of ways that animals get pointless pleasure, and published it in the journal Applied Animal Behavior Science. A few examples:

Herring gulls play "drop-catch," tossing around clams and other small, hard objects. Hippos go to the spa. When a hippo wants to unwind at the freshwater springs, they relax with their legs spread out and mouth wide open, and let the surrounding fish suck off parasites, flaky skin, fungus, and other blemishes. Sometimes they get so relaxed that they fall asleep. Dolphins use vibrators. They’ve been caught making low-pitched buzzing clicks near each others' private areas, and researchers say it seems to be an enjoyable experience. Certain birds have been caught masturbating, while goats, hyenas, primates, bats, and sheep appear to engage in oral sex.

In order to have fun, animals must have a brain that can process the pleasure. Some aren’t so lucky: Sponges and jellyfish aren’t conscious enough to really know what fun is.