7 Impressive Animal Defense Mechanisms

NOAA Photo Library, Flickr // CC BY 2.0
NOAA Photo Library, Flickr // CC BY 2.0

The deep-sea squid known as Octopoteuthis deletron has a startling defense mechanism: When threatened, the squid attacks its predator and then pulls away, breaking off the tip of its own arm and leaving it behind as a diversion. As the arm continues to glow and twitch, the squid makes its escape.

But this squid isn't the only creature with a bizarre tactic for keeping itself alive. Here are several other animals with impressive defense mechanisms.

1. THE LIZARD THAT SHOOTS BLOOD FROM ITS EYES

The Texas Horned Lizard is a scary-looking creature. Brown, plump and perfectly camouflaged in its native sandy environment, its first line of defense is its spiky demeanor. If the sharp spikes and horns don't ward off predators, the lizard steps it up a notch and squirts a well-aimed stream of blood out of its eyes. The stream of blood, which can go as far as 5 feet, is mixed with a foul-tasting chemical that wards off predators. But this odd weapon comes at a cost: The lizard may release one-third of its total blood supply this way, amounting to 2 percent of its body mass. Unfortunately, its population numbers are dropping thanks to a threat that won't retreat after a well-aimed squirt: habitat loss due to rapid urbanization in the Lone Star State. 

2. THE HAIRY FROG THAT BREAKS ITS OWN BONES

Trichobatrachus robustus, aka hairy or horror frog

Emőke Dénes, Wikimedia Commons // CC BY-SA 4.0

What if every time you felt threatened, your first and only method of defense was to break your own bones and use them for weapons? Meet the hairy frog, a Central African species. When breeding, the male frogs develop thin strands of skin along the sides of their bodies that resemble hair. In theory, these strands also allow the frogs to take in more oxygen while they watch over their eggs. But what's really compelling about this frog is its ability to crack its own toe bones and push them through their skin to form sharp claws, which are great for warding off would-be attackers.

While it's not completely clear what happens to the bones after the threat of attack subsides, researchers believe the bones slide back under the skin when the frog's muscles relax.

3. THE NEWT THAT TURNS ITS RIBS INTO SPIKES

spanish ribbed newt

The hairy frog isn't the only amphibian that uses its bones for weapons. When attacked, the Spanish ribbed newt shifts its ribs forward at an angle and pushes them through its stretched skin. The resulting effect is a row of spikes on either side of its body. Like the hairy frog, the newt has to force the bones through its skin every time it is attacked, but the mechanism seems to cause little or no harm to the creature. Maybe one day it'll get its own robot protector: A team of researchers at the the Swiss university EPFL created a robotic salamander inspired by the newt, which they called the Pleurobot (after its scientific name, Pleurodeles waltl).

4. THE TERMITE THAT BLOWS ITSELF UP

Talk about taking one for the team. When under attack, a species of termites found in the French Guiana rain forests sends older worker bugs on suicide missions to defend the whole colony. These older bugs, no longer as useful to the pack as they once were, come equipped with "explosive backpacks" that, over a lifetime, fill with toxic crystals produced by glands in the abdomen. When mixed with salivary gland secretions, these crystals create a toxic liquid that explodes on enemies, paralyzing them and killing the worker at the same time. These termites aren't alone among insects in using a suicidal defensive tactic: When faced with a threat, an ant found in Borneo expands its abdomen until it ruptures, shooting out a toxic liquid

5. THE FISH THAT SLIMES ITS ENEMIES

Hagfish are eel-shaped marine animals with the incredibly useful ability to slime their enemies. When threatened, the hagfish emit a slime from their pores that, when mixed with water, expands into a gelatinous goo that can either trap predators or suffocate them by clogging their gills. The video above shows a hagfish being attacked 14 separate times by sharks and other big fish, and coming out completely unharmed. Each predator took one bite before immediately spitting the hagfish out and swimming away, gagging. The best time to encounter a hagfish is probably after it's emptied its slime glands withstanding such an onslaught; the glands take three to four weeks to refill.

6. THE SEA CUCUMBER THAT SHOOTS ORGANS OUT OF ITS ANUS

sea cucumber on coral reef
iStock

Sea cucumbers can seem pretty boring. There are some 1250 known species of these sedentary creatures in the world, and many of them do indeed look like cucumbers. But when it comes to survival, things get interesting. Like starfish and sea urchins, sea cucumbers are echinoderms, and they can regenerate lost body parts if necessary. This comes in handy when they're threatened. The sea cucumber will expel its internal organs, which are sticky and sometimes contain a toxic chemical that can kill predators. They don't have much of a defense against pollution though, which is a problem, because they're superstar ocean-floor cleaners.

7. THE OPOSSUM THAT PLAYS DEAD

possum playing dead in the grass
Tony Alter, Flickr // CC BY 2.0

You can't do a roundup like this without at least mentioning the opossum. We typically refer to this creature's infamous defense mechanism as "playing dead," but there's actually nothing playful about it; the act is completely involuntary. Under intense fear, opossums fall into a comatose-like state that can last for hours, long enough to convince any predator that the opossum is already dead. Also unappetizing: Fear causes these animals to emit a corpse-like smell that only adds to their act. Thank the opossum for providing some defense for us too: They eat venomous snakes and ticks, gobbling up to 4000 insects a week.

5 Times the Jig Was Up Because the Parrot Squawked

iStock
iStock

Most of our feathered friends can sing, but only a few can talk. And if those talkers witness something naughty, they might just tell on you.

1. SUSPICIOUS SWEET TALKING

A woman in Kuwait, where adultery is illegal, had been suspicious for some time that her husband was carrying on an affair with their housekeeper. There were little signs, like when she returned home from work early and noticed that he seemed nervous. But it was when the family parrot squawked unfamiliar sweet nothings that she decided to take her suspicions to the police. If her husband wasn’t saying those things to her, how was the parrot learning them? However, because it could not be proven that the parrot hadn’t heard the phrases from a steamy TV show, the bird's evidence was deemed inadmissible.

2. THAT'S NOT MY NAME

In another case of infidelity revealed with a squawk, a man was surprised to hear his beloved African Grey parrot Ziggy say, “Hiya Gary!” when his live-in girlfriend’s phone rang, because his name was not Gary. After he heard the parrot say, “I love you, Gary,” and make kissing sounds when the name Gary was said on TV, he confronted his girlfriend, who admitted she was having an affair with Gary. Not only did he lose his girlfriend, but when the parrot continued to chatter on about Gary in her voice, the man was forced to give his pet up too.

3. THE AWFUL LAST LAUGH

Even when other evidence is already damning, a parrot can add an extra sinister twist to a crime investigation. When an elderly woman was found in a filthy South Carolina home, covered in bedsores and near death, her daughter was charged with elder abuse and neglect (her mother died the next day). The police noted that a parrot in the house repeatedly cried for help and then laughed. They believe it was mimicking the interaction between the mother and daughter: The mother pleading for help and the daughter laughing.

4. REPLAYING THE LAST WORDS

After a Michigan man was found shot to death in his home, his parrot kept repeating a dialogue, alternating between a man and woman’s voice, that went: “Get out.” “Where will I go?” “Don’t f***ing shoot!” His wife—who police believe tried to kill herself but did not succeed—was charged with his murder and was convicted in 2017.

5. GIVING THE CRIMINAL AWAY

Tales of parrots giving the criminal away go back to the 19th century, when the leader of a Paris crime syndicate who went by Victor Chevalier escaped with his beloved parrot from the residence he shared with his wife Marie before the cops descended on him. When an officer was called to another residence for a seemingly unrelated search, he heard as he walked in, a parrot cry out “Totor! Riri!” which happened to be the pet names of Victor and Marie. The discovery of the parrot eventually led to the capture of Victor.

This piece originally ran in 2016.

Scientists Reveal the Most Comprehensive Map of Butterfly Evolution Ever—and It's Gorgeous

Espeland et al., Current Biology (2018)
Espeland et al., Current Biology (2018)

There are 18,000 known butterfly species in the world, so maybe it’s not surprising that scientists haven’t quite worked out how they’re all related. Recently, scientists developed what is currently the most comprehensive roadmap of butterfly evolution ever, one that includes 35 times more genetic data and three times as many classifications as past butterfly evolutionary trees. Oh, and as Fast Company found, it’s beautiful.

The study, published in Current Biology, drew on genetic data from 207 butterfly species that together represent 98 percent of butterfly tribes (the classification just above genus). Led by Florida Museum of Natural History curator Akito Kawahara and Marianne Espeland of the Alexander Koenig Research Museum in Germany, the study used this genetic data and the fossil record to trace the evolution of different butterfly species and figure out when different species split off from their cousins.

A circular visualization of the butterfly family tree
Espeland et al., Current Biology (2018)

Needless to say, millions years of evolution means a lot of information to visualize in one family tree. Each bold label on the very outside of the circle represents a tribe, like Tagiadini, followed by the individual species that made it into the study, like Tagiades flesus (the clouded skipper). Species are clumped together by subgroup—in this case, Pyrginae (spread-winged skippers)—and color-coordinated by family—in this case, Hesperiidae (skippers).

The solid gray circle near the center, labeled K-PG boundary (for Cretaceous–Paleogene boundary) represents the mass extinction event that killed off most of Earth’s plant and animal species, including the dinosaurs.

A close-up of a circular visualization of the butterfly family tree
Espeland et al., Current Biology (2018)

The study confirms several pieces of information that butterfly experts had hypothesized about in previous studies, while overturning other hypotheses. Butterflies can be divided into seven different families, and though previous research estimated that the first butterflies appeared around 100 million years ago, this study pushes that date back to around 120 million years ago. But there were just a few early ancestors of butterflies prior to the mass extinction event that wiped out the dinosaurs, after which the butterfly family tree explodes into different branches.

Swallowtail butterflies (the subfamily Papilioninae, to the left in blue) were the first butterfly family to branch off, so they’re a “sister” species to all other butterfly species. Skippers (the family Hesperiidae, in purple) likely branched off next, then nocturnal butterflies like the Hedylidae family (in gray). However, some species that scientists previously thought were sister groups do not, in fact, share common ancestry, including swallowtails, birdwings, zebra swallowtails, and swordtails. The timeline shows that some butterfly species seem to have evolved together along with the plants they feed on or, in some cases, ant species with which they now have a mutually beneficial relationship.

[h/t Fast Company]

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