By Maria Yagoda
Updated February 12, 2016 04:00 PM

1. When a male penguin falls in love with a female, he searches the whole beach to find her the smoothest, most perfect pebble to present her as a proposal. (If she approves, she puts the stone in her nest.)

2. Cows have best friends.

3. Sea otters hold each other’s paws as they fall asleep so they don’t drift apart.

4. Seahorses are monogamous life partners. Sometimes they travel around holding each other’s tails.

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  • 5. Worms communicate by snuggling/squirming all over each other.
  • 6. Dolphins have NAMES FOR EACH OTHER, making them the only animal (besides humans) that are able to identify fellow creatures with a distinct sound. That we know of.
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  • 7. White-handed gibbons live in close-knit families. Coupled male and females spend a ton of time grooming each other and hanging out together.
  • 8. Swans swim beak-to-beak and tend to stay together forever.

9. Prairie voles mate for life – and are mad faithful. (A study found that when wifed-up males were tempted with “unfamiliar, virgin females,” fewer than 10 percent of them gave into the temptation.)

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  • 10. Bowerbirds construct fancy houses for the female they’re courting.
  • 11. Lions can have sex for up to 20 hours straight.

12. Albatrosses tend to settle down with a single mate for life.
13. Black vulture mates share parenting duties equally.

14. Sandhill cranes call out in unison, stick close together and often synchronize their movements.
15. Once cichlid fish hatch eggs, they spend all of their time fanning the larvae and fighting off potential predators. (If any of them wander off after hatching, the parents suck them into their mouths to keep them safe.)
16. Beavers spend as much time bonding with their life partners as they do building dams.
17. Male barn owls woo females with screeches and gifts of dead rodents. DAWWWW.