Animal self-defence experts

Predation is a natural part of animal life but some creatures put up a fight with weird and wonderful defence mechanisms

Skunks spray an obnoxious smelling musk

Although skunks look rather cute, they also have a very smelly trick that enables them to ward off predators. At the base of their tails are two large scent glands from which they can spray a pungent musk in the direction of their attackers. Skunks tend to aim for their victims’ eyes, shooting the fluid up to six metres (20 feet) away. The terrible rotten-egg like odour clings to skin and fur. It can also cause illness and temporary blindness, allowing the skunk to get away. The musk is composed of seven volatile components, including chemicals called thiols that produce the smell. Despite its effectiveness, skunks use this trick sparingly since they only have enough stored for a small number of sprays, and it can take up to two weeks to replenish. Only when an animal doesn’t pick up on the warning signs – the stamping of feet and the raising of the tail – does the full skunk force get unleashed.

Hairy frogs break their own bones and turn them into claws

Native to Cameroon, the hairy frog has a gruesome defence mechanism that could easily feature in a blockbuster science fiction movie. Studied by scientists at Harvard University’s Museum of Comparative Zoology in 2008, the frog has shown that it can break its own bones to produce sharp claws that slice through the toe pads of its hind feet. When it is resting, each claw is usually connected with collagen to a tiny piece of bone found at the tip of the frog’s toe. But by pulling the claw into the foot, the claw breaks away from the bone, producing a razor edge. This cuts through the skin and allows the bony claw to emerge through the toe pad. It is then used to fight off a predator.

Arthroleptidae --- Image by © Paul Starosta/Corbis
Uniquely, the hairy frog’s claw does not have a coating of keratin – it is just bone

 

Texas horned lizards shoot blood from their eyes

Texas horned lizards are fearsome-looking creatures with sharp spikes along their camouflaged bodies, and a couple of sizeable horns sticking out from the back of their heads. In most cases, the sight of the lizards alone would ward off curious predators but for the undeterred, there is a surprise in store. When the horned lizard feels threatened, it inflates its body to such an extent that it appears to be up to twice as large. Sometimes it also flips over, lies on its back and plays dead. Most predators turn away at this point, fearing the potential damage the protruding body scales could cause to their innards. Yet there are some that will persist. At this point, a stressed lizard allows blood pressure to build up around its face until vessels in the eye burst. This shoots jets of blood mixed with a foul-tasting chemical from the corner of its eyes at distances of some 1.5 metres (five feet) into the air. A lizard can do this a few times in quick succession, precisely directing the flow. Startled, the predator moves away.

corbis_42-25789520
The lizard allows blood pressure to build up around its face until vessels burst

 

Geckos discard their tails to baffle predators

A gecko can simply scream to ward away trouble when it feels threatened, but if that fails and an attacker gets hold of its tail, the lizard can fully detach it in a process known as autotomy. As the gecko continues on its way, the tail writhes and twitches in a complicated set of moves that lasts for a couple of minutes and makes the predator believe it has a live catch. Feeling victorious, the attacker is then distracted, giving the gecko enough time to scarper. Within six to eight weeks, the gecko’s tail grows back.

APWADC Leopard Gecko Eublepharis macularius Dist Asia India Iraq Afghanistan Pakistan
Geckos often return to eat their lost tail to give them the nutrients to grow another

 

Termites blow themselves up to defend their colony

Termite soldiers are able to destroy themselves in order to defend their colonies in a process known as autothysis. By putting pressure on a salivary gland until it bursts, they cause their bodies to explode, blocking tunnels and covering enemies in a sticky and corrosive substance. In 2012, scientists in French Guiana observed pale blue spots on the backs of older termites. It has emerged that these are explosive crystals that the insects store within exterior pouches, with the number of crystals increasing with age. This means that the older, less able termites still play a crucial defensive role within the colony. When attacked, the termites’ crystals mix with the salivary gland secretions to produce a highly effective toxin five times more deadly than normal. The enemy is showered with this deadly liquid as the termite’s abdomen explodes.

Termites (Nasutitermes sp) soldiers, Panguana Reserve, Huanuco province, Amazon basin, Peru.
Termite soldiers are able to destroy themselves in order to defend their colonies

 

Spanish ribbed newts rip their ribs through their skin

The first instinct of a Spanish ribbed newt when it feels threatened is to try to escape. If that fails, it will emit a toxin from the side of its body and neck, covering itself in a nasty-tasting substance that, in a lot of cases, proves to be very effective in warding off potential problems. But there is one, final stage for the most persistent or dangerous of predators. During an attack, the newt swings its ribs forward so that they are at a 50 degree angle to the spine, pushing against the skin. At this point, the ribs skewer through the skin and become spiky, external weapons. Surprisingly, this doesn’t appear to harm the newt. Indeed, it will happily continue to make fresh wounds every time it feels a threat to its life. It is certainly a good defence mechanism; not only do these new spikes puncture the mouths of predators, the skin glands secrete a toxin which coats the tip of the ribs. When a predator decides to take a bite, the terrible tasting poison is essentially injected into the thin skin of its mouth. Victorious, the newt is then able to heal.

Spanish Ribbed Newt (Pleurodeles waltl) against a white background. Captive occurs in Iberian Peninsula and Morocco.
The ribs skewer through the skin and become spiky, external weapons

 

Porcupines have a prickly suit of armour that can stick in the throat of predators

Porcupines have one of nature’s most distinctive defence mechanisms: hard, prickly hairs called quills. They have as many as 30,000 of these spiky structures covering every inch of their body except for the stomach. Should a predator get too close, they will suffer painful injuries. Each of the quills is made from keratin, the substance that forms our own hair and nails. A study by researchers at the City University of New York in 1990 showed that the quills have antibiotic properties, which help the porcupines to heal if they fall and accidentally prick themselves. They also each contain hundreds of microscopic barbs on their four-millimetre (0.15-inch) conical tips. This allows the quill to pierce the skin and flesh of a predator with greater ease but it also means that once they are embedded, they are notoriously difficult to pull out without causing further pain and injury. Predators are given ample warning, though. Porcupines are not normally aggressive, preferring to chatter their teeth, make grunting noises and emit a terrible odour when danger approaches. If that does not deter the oncoming animal however, the porcupine will lash out with its tail. It will also contract the muscles at the base of the quills, forcing them to stand erect. If a predator makes contact, several quills are pushed into the porcupine’s body. This cuts into the connective tissue, freeing them to stick into the predator’s skin. The porcupine can then make its escape. Its lost quills will grow back within a few months.

rexfeatures_4466480a-copy
The quills of a North American porcupine are usually 75mm (3in) long and 2mm (0.1in) wide.

 

World of Animals issue 40 is available from all good retailers, or you can order it online from the ImagineShop. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of World of Animals magazine, make sure you subscribe today!