Original photo by © Poelzer Wolfgang/Alamy
There’s no doubt that evolution is an incredibly creative problem-solver. Given enough time, it finds ways to overcome even the most complicated matters, including fundamental issues of survival.
For the majority of Earth’s living creatures, a crucial part of life is protection against predators. And here, evolution has been particularly resourceful — in some cases, creating survival tactics so strange they seem like the stuff of fanciful fiction. Here are seven of the weirdest animal survival tactics known to science.
The Frog That Freezes Solid in Winter
Most animals deal with winter by migrating, hibernating, or simply growing a thicker coat. But wood frogs — native to the northern forests of Alaska and Canada — take more extreme measures: They freeze themselves solid to survive the frigid winters.
The animals achieve this seemingly miraculous biological feat by pumping their body tissues with large amounts of glucose, which acts as a form of natural antifreeze to limit the formation of ice crystals which would otherwise burst their cells open. Their hearts, brains, and other organs are put into a form of stasis, their eyes turn white as the lenses freeze, and up to 70% of their total body water becomes extracellular ice. They can remain in this suspended state for 8 months, until spring arrives and the wood frogs defrost and hop away.
The Sea Cucumber That Expels Its Own Organs
The previous defense mechanisms may sound extreme, but the humble sea cucumber takes things to a whole new level. When threatened, the sea cucumber contracts its muscles, stretches out its sticky internal organs, and then blows them out of its anus into the path of any approaching threat.
The sticky organs are enough to distract, and potentially blind, the predator, giving the sea cucumber time to escape. This self-evisceration may sound like a bad deal for the sea cucumber, but it actually isn’t — sea cucumbers can regenerate their expelled organs within a few weeks.
The Fish That Produces a Whole Lot of Slime
The hagfish is a primitive, bottom-dwelling, eel-shaped jawless fish that’s been around for roughly 300 million years. When threatened, it uses specialized glands to emit a slime that expands in the water into a gelatinous goo that can either trap predators or suffocate them by clogging their gills.
Hagfish aren’t the only animals to produce slime under duress, but hagfish slime is unique because of the large volumes produced — one hagfish can eject several liters — and the near-instantaneous speed in which it’s generated. It’s a highly effective defense mechanism, but the hagfish can also get trapped in its own slime — something it deals with by tying a knot in its own tail, which it then passes forward along its body to remove any goop.
The Lizard That Shoots Blood From Its Eyes
The Texas horned lizard has a number of ways to avoid predation, including camouflage, sharp cranial horns, and the ability to flatten out its body. It’s also capable of squirting a foul-smelling, pressurized stream of blood from its eyes, up to a range of 5 feet.
When threatened, the lizard restricts the blood flow leaving its head until the pressure builds high enough to burst tiny vessels in its eyelids, launching the stream of blood and noxious biochemicals with impressive precision. Any predator gets a face full of nasty fluid, and the lizard lives to fight another day. Despite the auto-hemorrhaging, as it’s known, the lizard itself doesn’t suffer too much — it can even repeat the process several times within a short period of time if still threatened.
The Opossum’s Apparent Death
“Playing possum” is such a well-known phrase that many people assume the opossum is a skilled actor deliberately pretending to be dead. But in fact, the opossum has no control over the comatose-like state into which it falls when subjected to extreme fear. When confronted by a predator such as a dog, fox, or bobcat, the opossum involuntarily collapses — its body goes limp, its lips pull back, it drools, and it produces a smell like that of rotting flesh just for good measure.
The whole performance is entirely beyond the animal’s control, including when it snaps out of the coma-like state. It sounds like an incredibly high-risk strategy, but many predators are hardwired to attack only live prey and/or avoid decomposing flesh that could be toxic. As such, they often leave the “dead” opossum and move on, leaving the poor creature to eventually recover its senses and go about its business.
The Cute Primate With a Venomous Bite
With its large eyes, soft fur, and tiny hands, the slow loris is one of the cutest-looking creatures on Earth. But appearances can be deceiving: This furry mammal is actually the world’s only venomous primate.
Bizarrely, the slow loris produces a toxic secretion from a gland on the insides of its forelimbs, near the elbows. When threatened, it licks this gland, mixing the secretion with saliva to activate the venom, readying a toxic bite that can cause potentially fatal anaphylactic shock in predators.
Studies have shown many of those bites are intraspecific, meaning they occur within the same species, with territorial lorises biting even members of their own kind. So while they may look adorable, slow lorises are far from angelic.
The Octopus That’s a Master of Disguise
Mimicry is a fairly common survival mechanism in nature, but the appropriately named mimic octopus is a true master of disguise. Like other octopuses, it uses camouflage to blend into its surroundings — but it takes things a step further by actively impersonating more than 15 marine species, imitating not just their color and appearance but also their behavior.
The mimic octopus is a clever creature, selecting its impersonation based on the predator it faces. When threatened, it imitates specific venomous animals such as sea snakes, lionfish, and sole, discouraging predators that know to avoid those toxic creatures. It’s a contextual, elaborate theatrical performance — and one of the most impressive survival strategies in the entire animal kingdom.
Tony is an English writer of nonfiction and fiction living on the edge of the Amazon jungle.
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