They can’t put a ring on it, but when these animals find a mate, they’re ready to commit.
The furry, tree-swinging gibbon doesn’t monkey around with a lot of partners in its 35- to 40-year lifespan. Males and females form strong bonds and exhibit a surprising amount of relationship equality as they raise a family. They care for their young together, groom each other, and spend quality time vocalizing and hanging out. But not every relationship is perfect. Cheating, breakups, and remarriage all occur within the gibbon community. Sexting and online dating, however, do not. Yet.
2. Schistosoma mansoni
What’s a nice girl like you doing in a human like this? There’s nothing romantic about Schistosoma mansoni, a parasitic flatworm that uses freshwater snails to get to humans. Once it attaches to human skin, it usually penetrates the epidermis through a hair follicle and deposits larvae that feed on blood in the lymphatic system and lungs. When the larvae migrate to the heart, they start looking for The One. Male and female larvae monogamously pair off and eventually travel to the mesenteric veins that drain blood from the intestines. Together, they reach sexual maturity and produce about 300 eggs per day. Postively heartwarming.
It’s usually “’til death do us part” for wolves. In the wild, they start breeding by age 2, and mated pairs build their wolf pack by having a new litter every year. (Most wolves don’t experience reproductive senescence, either, and can have babies until they die.) So when you see a lone wolf, have some sympathy: He’s single and looking for love, mourning his dead partner, or, in extreme cases, nursing a breakup with the pack.
5. Shingleback Skinks
Unlike most reptiles, the shingleback skink of Australia only has eyes for one mate. Males make a series of moves—including caressing and licking females—before copulating. Courtship takes months, but partnered bliss can last over 20 years.
Only about 3 percent of mammals are socially monogamous, but leave it to beavers to show us how it’s done. After mating, the rodents spend as much time maintaining their relationships as they do their dams and lodges. The males and females co-parent their young and stay together until one partner dies. Attached beavers occasionally philander, but it’s not enough to break up the family.
6. Barn Owls
Some 90 percent of birds are socially monogamous, but that doesn’t mean they’re completely faithful to one mate. Barn owls, however, put all their eggs in one basket. Males woo females with screeches and gifts of dead mice. If the female responds with croaking sounds, she’s basically saying, “I do.”
7. Bald Eagles
Long-distance relationships aren’t easy, but bald eagles thrive in them. The birds fly solo during winter and migration, reconnecting with their mates each breeding season. Most eagles pair off by the age of 5 and stay together at least 20 years.
8. French Angelfish
Don’t let the name fool you. These lovers are aggressive fighters that do almost everything as a pair—hunting, hanging out in the reef, and defending their territory. And you thought your ex was clingy.
The brainiest invertebrate of them all usually keeps others at eight arms’ length. But when it’s time to mate, they dedicate their lives to one partner. Well, sort of. Octopuses only live one or two years, so they spawn once and then die shortly after. But the Pacific striped octopus is an exception; it has the ability to lay multiple clutches of eggs. Instead of mating once at a distance to avoid being eaten, these creatures mate face to face a number of times and even appear to kiss and fondle each other’s suckers. Get a room, you two!
We’ve already established that birds of a feather like to flock together, but the commitment of the male swan really stands out. In addition to helping their mates build nests, they’re one of only two male birds in the Anatidae (ducks, geese, and swans) family that share egg incubation duties.
A version of this story was published in 2016; it has been updated for 2023.