1. Dolphins are incapable of smiling. They open their jaw not to grin, but to listen.

2. In the 1950s series “Flipper,” all the dolphin noises were made by humans.

3. Dolphins don’t have vocal chords; instead, they use their blow holes to make sounds.

4. They pass air back and forth between the four air sacs in their heads to make whistle sounds.

5. Dolphins rely on eco-location—, a sonar-like ability to find objects— to hunt and stay with the pod. When eco-locating, they move their heads back and forth.

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6. Breaching can mean different things: For dusky dolphins, which feed at night, these leaps allow them to slap large surface areas of water and make noises to alert the pod that it’s time to hunt.

7. Male dolphins have thinner skin, which explains why they are often more scarred and scratched from acts of play and aggression.

8. The dorsal fin on a male killer whale can be up to 7 feet tall.

9. Bottlenose dolphins can’t be housed with beluga whales or harbor porpoises in captive facilities because they’ll kill them. They’re very aggressive.

10. In the United States, it’s illegal to swim with dolphins. You need a permit to do so.

11. Bottlenose dolphins live to be 45-50.

12. They weigh 300-400 pounds.

13. A dolphin’s age can be determined from a tooth: A special process of slicing and staining it reveals rings that can be counted like those of a tree cross section.

14. Dolphins don’t sleep the way we do because they are voluntary breathers. If they slept, they would suffocate or drown.

15. Dolphins don’t have hands, but they are capable of gesturing: the way they move their bodies, how they use their pectoral fin, where they touch each other, and whether they swim with their head up or down are just some of the ways they communicate physically.

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16. Dolphins are capable of using tools. In the wild, they’ve been seen carrying objects such as twigs and rocks.

17. Amazon river dolphins have been observed carrying big rocks. Marine biologists believe that the males do this to demonstrate to the females that they’re strong and that they have good genes.

18. The power stroke of a dolphin’s dorsal fin is the upswing.

19. Hector’s dolphins of New Zealand are the most threatened: Less than 8,000 individuals remain.

20. Only five species of river dolphins have existed (that we know of). One of those, the Chinese river dolphin, has been named functionally extinct. In other words, a few remain but the species will not survive.

All the above information was provided by Kathleen Dudzinksi, director of the Dolphin Communication Project, during Sea & Learn, a series of lectures and discussions held every October on the tiny Leeward Caribbean island of Saba. Special thanks to J.D. Ebberly for the dolphin photo.