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Why Have Australia’s Cane Toads Become Cannibals?

Cane toads were originally brought to Australia to get rid of farm pests, but now that their job is over, they're still hungry – and they've turned their appetites to the only available species: themselves.

With no predators to lessen the cane toad population, resources have become scarce, and tadpoles engage in battles to the death, with the winner dining on the loser. This cannibalistic behavior isn't uncommon in the species' natural home in South America, but the Australian version is much more widespread.

Due to cannibalistic behavior, Australia's cane toad tadpoles have sped up their development to avoid being eaten.
Due to cannibalistic behavior, Australia's cane toad tadpoles have sped up their development to avoid being eaten.

With cane frog tadpoles facing such dire danger of being devoured, they have somehow learned to grow up faster, thus becoming less of an easy mark for other hungry tadpoles. For example, the hatchling stage of South American cane toads is five days; in Australia, it's only three days. For the record, there are now an estimated 200 million cane toads in Australia, all coming from an original 2,400 released in 1935.

Cane toad talk:

  • Western Colombian Choco Indians once coated the tips of their arrows and darts with concentrated poison from cane toads.

  • One cane toad raised in captivity grew to a record 14 inches (35.5 cm) in length, and 5 pounds 13 ounces (2.6 kg) in weight.

  • Despite common belief, licking a cane toad won't get you high, but it can make you incredibly ill.

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    • Due to cannibalistic behavior, Australia's cane toad tadpoles have sped up their development to avoid being eaten.
      By: Michael Eisen
      Due to cannibalistic behavior, Australia's cane toad tadpoles have sped up their development to avoid being eaten.