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Flesh-Eaters: 5 Cannibalistic Animals

Did you hear about the cannibal who was late for dinner? He got the cold shoulder.

Some humans might find cannibal humor in bad taste, but for some animals, it’s no joke. Here are a few creatures for whom “I’d like to have you over for dinner” is a terrifying invite. (See “Surprise! Male Spiders Eat Females, Too.”)

Sand Tiger Shark 

They say the earlier you learn something, the better it will stick. Well, no wonder sharks are such world-class killers: They start before they’re born.

Grey Nurse Shark (Carcharias taurus) swimming near Papoose Wreck off North Carolina
A sand tiger shark swimming off the shores of North Carolina. Photograph by Norbert Wu/Minden Pictures/Corbis

The year-long pregnancy of a female sand tiger shark may begin with six or seven embryos in her two wombs, but only one per womb will make it to birth, the CBC reports.

The first to break out of its egg capsule will start feasting on its siblings. When this baby shark finishes off its brothers and sisters, it will start on unfertilized eggs that have entered the womb. The protein-rich diet works: At already about three feet (a meter) at birth, the newborn sand tiger shark is unlikely to become prey.

Prairie Dog

They’re the cutest infanticidal cannibalistic serial murderers you ever did see.

Two Black-Tailed Prairie Dogs, cynomys ludovicianus,.
These black-tailed prairie dogs may look cute, but… Photograph by Universal Images Group via Getty Images

Not all prairie dogs merit such dastardly designations, but we know some do, thanks to the tenacious research of John Hoogland, behavioral ecologist at the University of Maryland Center for Environmental Science. After some major detective work discovered cannibalism among black tailed prairie dogs. (See video of Hoogland on NatGeo Wild: “Prairie Dog Alarms.”)

“We noticed that almost all the females were mating, but very few were weaning babies,” said Hoogland, who began researching the rodents in 1974.

The team also noticed females going into the burrows of their closest female relatives, and “when they come up, they frequently had some blood on their faces.” Mothers in those burrows stopped showing any signs of maternal behavior.

Eventually, after much effort, “we found decapitated babies that had mostly been cannibalized down there,” Hoogland said. “Now we had the smoking gun.”

Another species, the Utah prairie dog, also eats its young but the behavior is rare or non-existent in other species.

“My guiding hypothesis,” he said, “is that competition is so extreme that sometimes natural selection favors prairie dogs to kill the offspring of close relatives because doing that raises the chances that their own babies make it.

“In that sense,” Hoogland says, “it really is a dog-eat-dog world.”

Cane Toad

Dog-eat-dog, yes … but frog-eat-frog?

Some of the thousands of cane toads caught by the residents of Cairns Australia overnight and entered into the "Toad's Day Out" program, await euthanasia by freezing in Cairns, Australia, Sunday, March 29, 2009.
Thousands of cane toads await euthanasia by freezing in Cairns, Australia, on March 29, 2009. Photograph by Brian Cassey, AP

Well, sort of. The tadpoles of cane toads, which are native to South America, like to dine on cane toad eggs, which they sniff out in the water. They’re specifically attracted to an egg-protecting toxin called bufadienolides. The nutritious caviar helps them develop and cuts down on future competition, according to a 2011 study from the University of Sydney and James Cook University.

But it’s not just the kids: A 2008 study found that cane toads waggle the middle toe of their hind foot in a luring display to attract prey, including young toads. In that study the researchers dissected 28 juvenile cane toads and found that 64 percent of their 149 prey items were other cane toads.

Alas, like so many of us, the cane toad may be undone by its own appetites. They’re an invasive species in Australia, and many people are working to eradicate them. (See a picture of a monster cane toad caught in Australia.)

Snakes

Just because you’re a snake doesn’t mean you won’t end up as a snake snack: Some species of garter snakes and king snakes might eat each other if housed together.

Close up photograph of Mexican Lance Headed Rattlesnake. Crotalus polystictus
A Mexican lance-headed rattlesnake. Photograph by Darren Green Photography/Alamy 

2009 study of Mexican lance-headed rattlesnakes showed that 68 percent of new mothers ate all or part of their non-surviving offspring, probably to recover the nutrients needed to reproduce again.

A wonderfully descriptive New York Times story from 1901 describes an outsize female cobra at the Bronx Zoo who snacked with such gusto on black snakes provided to her that “already her appetite has made black snakes scarce in the park.” (Watch video: “Cannibalistic Snakes.”)

Snakes will even bite themselves on occasion. Check out this video of a copperhead that chomps down on its own tail … after its head has been cut off.

Australian Redback Spider

“Love bites,” “hungry for love,” “I could eat you up”—human sexual desire is rife with food metaphors.

Redback spider (Latrodectus hasselti), female with legs spread out over web; males are small and rarely noticed. Albany, Western Australia.
A female redback spider seen in Albany, West Australia. Photograph by Auscape/UIG via Getty Images

In the micro-world, they’re not metaphors.

Some insects and arachnids practice sexual cannibalism, wherein the female eats the male after mating. Australian redback spiders get both acrobatic and deliciously spiteful about it.

The male redback will sacrifice itself to the female by somersaulting onto her mouthparts during sex and can transfer sperm while being consumed.

Maydianne Andrade of the University of Toronto Scarborough reported in a 2003 study that males that are cannibalized (which happens 65 percent of the time) mate far longer and produce twice the number of offspring than those that are not.

So, ready for that afternoon snack?

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Comments

  1. ramlix
    Rizal , Philippines
    February 19, 4:36 am

    so sad about cute carnivores

  2. jerry swafford
    leesburg FL
    January 20, 6:14 pm

    a snake eating a different type of snake is now cannibalism because they’re both snakes? a human eating a cow would be cannibalism by that definition, since they’re both mammals. really hoping for slightly better scientific accuracy from a natgeo article.

  3. Melissa
    Atlanta
    January 18, 10:29 am

    When I was little I had a pet pair of mice. Named Romeo and Juliet. Well needless to say they followed suite. After mating, Juliet decapitated and ate Romeo, only to later die after giving birth. It all apart of natural selection. But very interesting.

  4. Liz Langley
    January 16, 8:55 am

    @Robert C Brooke @Achlen Daniel-Browne

    Interesting! I didn’t find anything about cannibal cats while I was researching but your comments made me curious so I looked around and did, indeed, find references to it online. Thanks!

  5. Dr Bob
    Harlingen, TX
    January 15, 7:22 pm

    I was raised on a farm. We always raised some hogs for meat and market. When the sows had their litters, my sister & I would take the baby pigs from the sow as soon as they were born to prevent the sows from killing and eating the piglets. The same was true of rabbits. If you didn’t remove the babies those cute little bunnies would kill and eat their progeny. Point is, this behavior is nearly not as unusual as you would lead people to believe.

  6. Achlen Daniel-Browne
    Montserrat, West Indies
    January 15, 7:20 pm

    Cats eat still-borns &/or new-borns that don’t survive long. That may be an extension of some animals eating the afterbirth.
    I once saw a documentary where a new anaconda mother Actually Checked to make sure her young were Definitely dead Before she ate them. That was her best option for nutrition since she was weak from giving birth.

  7. Larry Higbee
    Rossmoor, CA
    January 15, 6:48 pm

    I am so surprised that the one animal I find most frightening, didn’t make the list. Chimpanzees are known to attack and devour another of their own tribe in the wild. Yikes!

  8. Robert C Brooke
    January 15, 3:19 pm

    Cats occasionally engage in cannibalism.We’ve had two occasions in which the runt of a litter got eaten.

  9. Suhey Ortega
    Phoenix, AZ
    January 15, 11:10 am

    That’s really funny Ruth!

  10. lola rosique
    Barcelona Spain
    January 15, 10:35 am

    Totally amazing!

  11. Ruth Amick
    Agoura Hills, Ca
    January 15, 1:18 am

    When I worked for a large pet supply store, I used to try to advise them to refrain from housing the Russian hamsters in groups. They would often kill and eat each other; I told them they didn’t enjoy living with other hamsters in such close proximity. The store management never listened.