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Defense mechanisms are a series of adaptations, including organs, that some animals have and that allow them to avoid being hunted by their predators. They are conserved evolutionary advantages because they increase the species’ chance of survival in a world where natural predators are constantly trying to hunt them down.
Types of defense mechanisms in the animal kingdom
Any adaptation that in one way or another allows an animal to evade a predator, drive it away, or survive its attack can be considered a defense mechanism. In this sense, animal defense mechanisms are many and varied. However, they can be classified into the following categories:
- escape mechanisms.
- Hiding place.
- Animal mimicry.
- Bioluminescence.
- Secretion of chemicals.
- Sound generation.
- Protective physical traits.
- Animal defense weapons.
- Defense by behavior (playing dead, aggressive behavior).
- Detachment of body parts.
- Cunning.
- Group surveillance.
- Association with other species.
escape mechanisms
One of the first ways animals avoid becoming prey is through flight. In this sense, agility and speed are the keys to success, and there are multiple examples of animals that are capable of surviving and evading the attacks of their predators thanks to their ability to escape. Examples of this are numerous in the African savannah, where animals such as gazelle, impala and zebra depend on their ability to run long distances at high speed to evade lions, cheetahs and leopards.
However, the ability to run is not the only form of escape defense. Birds also use their ability to take off quickly and take flight to avoid being eaten by terrestrial or aquatic predators. In the case of the blue Morpho butterfly, it is characterized by undertaking an erratic and unpredictable flight that makes it very difficult for its predators to catch it.
Likewise, in the sea many fish depend on their ability to swim quickly in a straight line and to make sudden changes of direction that confuse their predators.
Hiding place
When we talk about hiding, we refer to the ability of many animals to find places where predators cannot reach them. We are not referring to camouflage, which will be discussed in the next point, but to the ability to hide in holes, between rocks or at the height of the treetops. Many animals depend on their ability to hide so that predators can’t find them. Animals like the weasel and the scorpion hide in caves to defend themselves from their predators.
Other species of animals live and hide in burrows built by themselves or by others who abandoned them. Common examples of animals that live in burrows include moles, foxes, groundhogs, and devilfish.
The color
Color is an important element of defense in the animal kingdom. Most poisonous or toxic animals are brightly colored, and many predatory species have learned not to mess with these animals. Thus, the presence of bright colors in other harmless animal species also serves as a defense and warning mechanism that deters many attackers.
animal mimicry
Perhaps one of the most striking and well-known animal defense mechanisms is mimicry. This refers to the ability of some animals to imitate the appearance or some other characteristic of their natural environment or of other animals.
The best known form of animal mimicry is camouflage, which consists of the ability to blend in with the environment until it becomes almost indistinguishable from it. In some cases, the camouflage is permanent and only works in certain environments, such as owls, whose plumage makes them almost indistinguishable from the logs in which they nest.
On the other hand, other mimicry mechanisms are more spectacular, such as the popular chameleon, which is capable of altering the color of its skin by imitating the color of its surroundings, effectively blending into it in the eyes of its predators (and also of their prey, by the way).
There are also more extreme cases in which the animal appears to be invisible or transparent, as is the case of the glass butterfly, which literally lets you see through its wings.
But mimicry is not used solely to become invisible to predators. In some cases, the animals present physical traits and even behaviors that mimic those of other dangerous or disgusting animals, in such a way that they scare off their predators. This mimicry, called Batesian mimicry, is very common in the animal kingdom. For example, such is the case of the caterpillar of the Hemeroplanes triptolemus butterfly , which has the peculiarity of presenting a thickening at one of its ends with two lateral spots that makes its tail almost identical to a snake.
There are different species of this caterpillar that resemble different snakes, but their resemblance does not end with their appearance, but this caterpillar, apparently aware of the fear that snakes instill in the animal kingdom, also imitates snakes by raising its tail and moving it in the same way that a snake would move its head.
Another example of Batesian mimicry is the one used by the false coral or Lampropeltis triangulum , which has a size and a combination of color rings very similar to that of the highly poisonous coral snake ( Micrurus frontalis altirostris ).
bioluminescence
Bioluminescence, or the ability of a living organism to produce and emit light, can be used as a defense mechanism in the animal kingdom. In these cases, the animal in question lights up like a light bulb when it feels threatened by a predator, which, in some cases, manages to scare it away or, at least, confuse it. A species that uses this kind of defense mechanism is the millipede, which is also capable of secreting a toxic substance as an alternative defense mechanism, in case the light warning is not enough, which leads us to the next mechanism animal defense.
Secretion of chemicals and other fluids
Bioluminescence as a defense mechanism is rare in the animal kingdom (in fact, bioluminescence in general is rare). Instead, the secretion of chemical substances of different types is a common and effective mechanism present in all types of animals, from terrestrial to aquatic animals, vertebrates or invertebrates. The types of chemical substances are very varied and so is their function. Some examples of the use of chemical substances as means of defense are:
- Poisons and other toxic substances: Many animals have special glands that secrete potent toxins capable of poisoning their predators. In some cases these substances are limited to causing discomfort, but in other cases they can be fatal. Some common examples of this mechanism can be found in many species of toads (such as the natterjack toad, for example), in which the substances are usually irritating and in some cases hallucinogenic. However, frogs are famous for the dangerousness of their secretions. For example, the golden dart frog found in the Colombian jungles is considered one of the most poisonous animals on earth.
This small amphibian, five centimeters in length, releases a neurotoxin that inhibits neuromuscular conduction, leading to almost instantaneous respiratory and cardiac arrest and causing the death of anyone who dares to threaten it. A single golden dart frog can release enough toxin to kill 100 adult humans.
- Irritating substances: in some cases, the animal is capable of releasing and even spraying a substance that is irritating to its predator. Many beetles and other insects such as ants have the ability to release formic acid. In the case of the bombardier beetle, it combines a set of chemicals in a special abdominal chamber, which react explosively before being expelled at boiling temperatures in the form of a boiling and irritating spray.
- Stinky Substances: Another classic example of chemical defense is the release of foul-smelling substances. Skunks, mapurites, and skunks are examples of animals that, when threatened, contract specialized glands that spray a stinking musk that is also irritating to the eyes.
- Blood secretion: there are cases in which the threatened animal sprays the predator with blood to scare it away. This is the case of the horned lizard, which releases jets of blood through two shuttles that it has in each of its eyes.
sound generation
Certain animals emit particular sounds as a warning to their predators. For example, the rattlesnake is known mainly for the presence of a structure in its tail that, when shaken, emits a characteristic sound like a maraca. Whenever this snake senses a threat approaching, it begins to wag its tail in warning.
In other cases, they use sounds to alert other members of their community to the presence of a predator. For example, many monkeys scream and make different noises to communicate with each other and have different warning signals for different predators.
Protective physical traits
Mechanical defense mechanisms are also typical in the animal kingdom. In the sea we can find many animal species such as mollusks that have an exoskeleton or protective hard shell that allows them to avoid being eaten by fish and octopus. Some crabs also use shells from other animals as shields to protect themselves from predators.
In the case of terrestrial animals, we can find animals with almost indestructible shells, such as those of turtles. There are also animals whose skin is extremely thick and difficult to penetrate, such as elephants and rhinos.
On the other hand, animals such as the armadillo and the cachicamo also have hard cuticular structures around their body that allow them to protect the softer parts such as their belly. Many prehistoric animals also had these same types of defense mechanisms to protect themselves from large carnivores.
Finally, some animals, such as hedgehogs and porcupines, are lined with spines that stick into the mouths of predators that try to eat them. They are even capable of projecting these spines as a defensive attack.
animal defense weapons
While shields such as carapaces and shells provide defensive protection against a predator, there are animals that possess weapons that they can use to engage predators and literally fight for their lives. Horns are the most common example of this type of defense mechanism, although other types of weapons existed in prehistoric times, such as the tail of the stegosaurus or the massive ball- or hammer-shaped tail of the ankylosaurus.
defense by behavior
There are two very different kinds of defense that are related to an animal’s behavior when feeling threatened.
The first is to play dead. Unlike scavengers, predators only eat what they or other predators kill and will typically leave an animal that appears to have died of natural causes such as disease. Some animals take advantage of this and play dead when they sense danger is near. A classic example of an animal using this defense mechanism is the North American opossum, which, to be more convincing, lies motionless with its mouth open and tongue out, and in addition to emptying its intestines, secretes foul-smelling substances that they make it look like the animal has been decomposing for several days.
At the other extreme, we have really harmless animals that, feeling threatened by a predator, engage in extremely aggressive behavior in order to intimidate the predator and drive it away.
detachment of body parts
Those species that have the ability to regenerate the body often take advantage of this ability as a defense mechanism. In these cases, the animal sheds some unimportant part of its body to confuse and entertain the predator while it flees. An example of this defense mechanism is lizards that detach from their tail, which continues to move even after it is separated from the animal’s body.
On the other hand, sea cucumbers have the peculiarity that they can send part of their internal organs through their anus.
Swarm behavior and other collective defense mechanisms
Something that some animal species understand very well is that there is strength in unity. When you’re a small, helpless creature like an ant, there’s no way you can stand up to a large predator on your own. However, when instead of one ant an army of thousands of them appears, things change. Many insects have collective defense systems that allow them to deal with threats much larger than themselves. Ants are just one example. Bees and wasps are too.
In the case of the marine world, many fish move in large schools sometimes made up of thousands of fish. In these groups, the fish move in unison, as if they were a single organism. This coordinated collective behavior is one of the keys to preventing sharks, dolphins, whales and other predators from catching them.
Association with other species
Lastly, some animals develop symbiotic relationships with other animal species or with some plant species, taking advantage of their characteristics to defend themselves from their natural predators. There are many examples of this type of defense mechanism in the animal kingdom, but perhaps the best known is that used by the clownfish, made popular by the Pixar film Finding Nemo. This species of fish is capable of living among the poisonous anemones, covering itself with a film that makes it undetectable for them. Anemones are very poisonous to most other fish and marine life, so living among anemones gives clownfish very good protection from predators.
On the other hand, butterfly caterpillars of the Lycaenidae family secrete a sweet liquid when they feel threatened. The ants love this liquid and are attracted to it, defending the caterpillar against its predators in order to enjoy it.
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