Think you know everything there is to know about your favorite furry, finned or feathered friend? Chances are there are some interesting facts that even the most ardent animal-lover may be surprised to learn.

1. Tough tongue: Cats’ tongues are covered with little structures called “filiform papillae,” which are like tiny hooks pointing toward the throat. These hook-like structures help hold food while a cat is eating. The papillae also help with grooming. Humans can feel these barbs when licked by cats.

2. Seeing spots: Dalmatians are born all white. Their spots will develop within the first few weeks of life and can be black, brown or liver colored.

3. Sleepy time: Cats are born loungers and will spend on average 16 hours of the day snoozing. Only sloths spend more time asleep.

4. Send a message: Fish do not have vocal chords, but they can use low-pitched moans, grunts, hisses, and wails to communicate with one another.

5. Watch the eyes: Pet birds can communicate feelings through their pupils. If pupils are dilated, the bird is calm. Pinprick-sized pupils mean birds are agitated and may bite.

6. Meeeoooowww: Cats only meow to communicate with humans, not amongst themselves.

7. Seeing colors: Dogs are not color blind as once presumed. They can see colors, just not as vividly as humans.

8. Kindles are not just for reading: A group of kittens is called a “kindle,” while a group of cats is a “clowder.”

9. Almost wild: Dogs are so genetically similar to wolves that they can interbreed.

10. Noseprints: Cats’ and dogs’ noses are unique, just like human fingerprints.

11. Fishy growth rings: Fish do not add new scales as they grow. The scales increase in size and form growth rings that can reveal the age of the fish.

12. Not domesticated: Birds are not domesticated. They’re still rather wild and must be taught acceptable pet behavior.

13. Barkless: Many dogs do not actively bark. One dog that rarely ever barks is the Basenji, due to a narrow larynx. It can yodel, however!