Animals Where You'd Be Surprised to Learn How Much They Are Related

Nowadays, animals (and living creatures in general) aren't classified based on morphological similarities but rather on genetic relationships. In some cases, these relationships differ greatly from what we might expect. For instance, while most of us know some close relations like the mammoth and the elephant, can you guess who the closest living relatives of elephants are? You might assume rhinoceroses or hippos, but the actual closest relative doesn't resemble elephants at all.

You might wonder how close the relation needs to be between animals to qualify for this list. For example, you could say, "Of course elephants and hyraxes are related. They are both mammals." That's correct, but such a connection might not seem surprising. This is a subjective list, so if you add items, you need to determine whether a relationship is close enough to be surprising.

1. Crocodiles and Birds

   While at first it may be a surprise that birds' closest living relatives are crocodiles, it isn't astounding if you think beyond. Most of us know birds are related to reptiles, but it's a lesser-known fact that crocodiles are less related to turtles (some other reptiles) than to birds.

2. Elephants and Hyraxes

   Hyraxes are the closest living relatives of the three elephant species. There is even an African language in which hyraxes are called the small brothers of elephants. Hyraxes have no very close relatives, so they make up an individual order called Hyracoidea. If you haven't heard of them, check them out. They don't resemble elephants in any way.

3. Primates and Treeshrews

   This is actually a pretty well-known fact, but it still surprises most people. Treeshrews have the largest brains in proportion to the rest of their body. While the resemblance is minimal, I actually find treeshrews' ears somewhat similar to human ears. The order of animal groups from the most related to humans:

   1. Chimpanzees

   2. Gorillas

   3. Orangutans

   4. Gibbons

   5. Cercopithecidae (e.g., swamp monkey, talapoin, macaque, vervet)

   6. New World monkeys

   7. Tarsiers

   8. Every other primate

   9. Flying lemurs

   10. Treeshrews

   All these animals together make up the clade Euarchonta.

4. Sharks, Raja Rays, and Rabbitfish

   Sharks and rajas are two types of cartilaginous fish commonly known. Rabbit fish (not to be confused with rabbitfish) are lesser-known and they look nothing like sharks and rajas.

5. Cats and Dogs

6. Flies and Fleas

   Not the most surprising on the list, but I would think that flies' (which includes mosquitoes) closest relatives are bees or wasps. Flies and mosquitoes make up the order Diptera, while they form a bigger clade with fleas (which is a separate order as well). Their next closest relatives (excluding some obscure groups) are butterflies.

7. Hedgehog Tenrecs and Golden Moles

   This is more like "animals you'd be surprised are NOT related." Hedgehog tenrecs look exactly like hedgehogs at first glance, then you realize their heads don't resemble hedgehogs at all. Together with golden moles (who aren't closely related to moles), hedgehog tenrecs (not closely related to hedgehogs) belong in the order Afrosoricida. Real hedgehogs' relatives are shrews (who aren't relatives of treeshrews and elephant shrews).

8. Hyenas and Cats

   Believe it or not, hyenas are closer relatives of cats than dogs. They both belong in the suborder Feliformia, while dogs are in Caniformia, together with bears, weasels, and seals.

9. Elephant Shrews and Elephants

   When you see an elephant shrew, you would think there's more shrew in it than elephant, but it is the opposite case. I put it low because the relation isn't very close: they only belong to the same superorder of placentals but different orders.

10. Albatrosses and Penguins

    Not sure if this is surprising or not. Penguins make up a separate order of birds, and the closest related order of birds consists of various seabirds, including albatrosses, petrels, storm petrels, and shearwaters.

The Newcomers
11. ?

    Sloths and Anteaters

    Can't believe I had to add this one. They are members of the same order: Pilosa, which is part of Xenarthra (which also includes armadillos).

12. ?

    Kangaroos and Koalas

    Yep, both are diprotodonts. So are wombats, possums (not opossums - those are didelphimorphs), cuscus, etc.

The Contenders

13. Carnivorans and Pangolins

    Carnivore here refers to an order of mammals consisting of (among others) wolves, foxes, seals, hyenas, and cats. Together with pangolins, they make up the clade Ferae, which was the original name of the carnivore group in Linnaeus' times.

14. Hippos and Whales

15. Falcons and Parrots

    Falcons are more closely related to parrots than to hawks.

16. Chickens and Dinosaurs

    Birds and reptiles are often considered by some to be "the last living dinosaurs." I'm not sure if they're related, but they were living at the time of the dinosaurs.

17. Canines and Raccoons

    Dogs are related to trash pandas? Interesting.

18. Crustaceans and Insects

    Wait, the crabs, lobsters, crawdads, and shrimp (crustaceans) we eat are related to the little buggers that fly around us? I never knew that.

19. Carnivorans and Ungulates

    Together with pangolins, cetaceans, and bats, they are the clade Scrotifera.

20. Crocodiles and Alligators

21. Tenrecs and Elephants

22. Humans and Lemurs

23. Deer and Cattle

24. Horses and Rhinos

    Tapirs are the third family of the order Perissodactyla.

25. Jellyfish and Sea Anemones

26. Cephalopods and Gastropods

27. Spiders and Horseshoe Crabs

    I've actually heard about that before.