DEFENSE MECHANISMS OF ANIMALS

Different Defense Mechanisms

of Animals

By: Jorgielyn C. Serfino BSIS 1-A

Defense Mechanisms

Defense mechanisms are very important to all animal life. Animals must eat to survive. With predators always on the lookout for a meal, prey must constantly avoid being eaten. Any adaptation the prey uses adds to the chances of survival for the species. Some adaptations are defense mechanisms which can give the prey an advantage against enemies.

Types of Animal

Defense Mechanisms

Types of Animal Defense Mechanisms

The best way to defend oneself is to run away from the clutches of the enemy. Some animals can bite when seriously provoked, but their first line of defense is usually to hide or flee.

SPEEDY ESCAPE

Fish use their genius at swimming and kangaroos use their talent for fast running to escape from predators.


fishes kangaroo


WEAPONRY Animals use their unique body parts to fight or

to defend themselves from predators. Some animals' physical features make them a very undesirable meal.

Antlers and horns or teeth or claws and hoofs are used with full force when an animal senses a threat to its life. The canine teeth and sharp claws of carnivores are actually related to their carnivorous feeding habits but may also be used for defense.


Spikes on a hedgehog’s back Spines on a sea starSharp toothed hippopotamus

Wild rams fighting Short-beaked echidna Gavial


ARMOUR

Some animals have developed external or superficial protection against attack by predators, formed as part of the body usually through the hardening of body tissues, outgrowths or secretions.

Scales and scutes cover the body of certain animals such as pangolin (the scaly anteater) and crocodiles.The shell of tortoises and turtles also forms armour against enemies. In most turtles a horny layer of epidermal scutes overlies the dermal shell.


Giant tortoise Red Rock Crab

Nile Crocodile

Chinese alligator Alligator snapping turtleScaly Pangolin


Some animals use chemical secretions from their body to deter attackers.

Ex. Striped and spotted skunks simply direct the anal glands which produce the stinking secretion straight at their foes. Sea cucumbers turn themselves inside out by excreting sticky filaments from their anus when attacked by their enemies. African spitting cobra sprays venom at the eyes of a predator as far as 3m. When under threat, sea cucumbers rapidly eviscerate, ejecting part or all of their digestive tract. This is done to either anchor the cucumber into a rock fissure, or to eject toxins at the predator.

STINKING SECRETIONS


Beetle excretes hot gas

Octopus ejecting ink

Spotted skunk produces foul smell

Poison arrow frog

African spitting cobra


FEIGNING DEATH OR PLAY INJURED

Some animals freeze in cover or play dead to appear as lifeless to a predator. Often this is accompanied by foul smells, as if their corpse is in an advanced state of decomposition, one which many animals would avoid consuming. As an absolute last line of defense, many insects taste extremely bitter, so that once a predator has begun to feed they quickly stop, and, if this is a less vital area such as a leg or a wing, the insect survives the encounter.


OpposumThe opossum has an involuntary comatose-like state induced by extreme fear.

Plovers move away from the nest site and bend down on the ground as if they are injured so that their predators feel they can catch them very easily. Later they escape.


Animals produce ultrasonic noises and sounds to escape from predators or to give a message to their predators that they will be difficult to capture.

PRODUCING SOUND/NOISE

Tiger moth Skylark


This can also be used as a formidable defense. False features that appear to be enormous eyes or appendages can serve to dissuade potential predators.

TRICKERY

The moth Automeris io possesses eyespots hidden on its hindwings. When under threat, the moth suddenly reveals these spots, aiming to startle its predator. Fearful of their own consumption, predators often retreat when startled. Eyespots are also used by some animals to trick a predator into thinking it has been spotted (when in fact, it may not have been), and so is less likely to succeed in pursuit.

Cuban brown anole with extended dewlap

Automeris io with false eyes

Australian moth with false eyes


• Autotomy, the shedding of a non-vital body part, is utilized by some species to escape the grasp of a predator.

Armored crickets also utilize the method, known as autohaemorrhaging. These animals are able to survive the loss of these tissues, and later regenerate them. Horned lizards, when threatened, increase the pressure in their sinus cavities until the blood vessels in the corners of the eyes burst, squirting blood at the attacker.

oDRASTIC APPROACH


The Camponotus saundersi soldier ant undergoes a process called autothysis to defend their ant colony. They have two large glands that run the entire length of their body, and when stressed during battle, abdominal muscles contract, causing the glands to explode, killing the ant, but spraying poison in all directions.

Lizards sacrifice part of their body to save their own life. It can shed its tail and run off when attached leaving the predator distracted by the wriggling body part. The tail eventually grows back, but the predator cannot even eat the tail that was left by the lizard because of the parasites in its tissue.


Lizard shedding off tailA fishing spider with two limbs missing

A white-headed dwarf gecko with tail

lost due to autotomy.

Soldier ant explodes


Mimicking an animal that is dangerous to a predator is another effective means of avoiding being eaten.

Nonvenomous Sinaloan milk snake (right) mimics the venomous coral snake.(left)

MIMICRY



Another defense mechanism is camouflage or protective coloration. One form, cryptic coloration, allows the animal to blend in with its environment to avoid being detected. It is important to note that predators also use cryptic coloration to avoid detection by unsuspecting prey.

CAMOUFLAGE /PROTECTIVE COLORATION


Matamata Leaf mantis Moth tree

spider flounderLeech camouflaged as a thorn


Pufferfishes have the ability to inflate themselves into a balloon shape by swallowing water. Their bodies are also covered with thorny spikes, which stand out on inflation, providing a formidable defense against attack.

ABILITY TO INFLATE SELF


Defense mechanism of a Pufferfish

Click on the video to play and stop


Animals that are the frequent target of predation often make use of 'safety in numbers'. This results in a situation where any one herd member is unlikely to be preyed upon, and in high populations.

oBEING SAFETY IN NUMBERS

Grazing animals such as sheep, working as a group, a stalking predator is likely to be detected earlier, and when it attacks, the herd scatters, causing difficulty for the predator and allowing most, if not all, of the prey animals to escape.


elk sheep

Defense Mechanism in relation to

Ecological Balance(Predator-Prey Relationship)

To sum it all up, the predator-prey relationship is important in maintaining balance among different animal species. Adaptations that are beneficial to prey, such as defense mechanisms, ensure that the species will survive. At the same time, predators must undergo certain adaptive changes to make finding and capturing prey less difficult.

Without predators, certain species of prey would drive other species to extinction through competition. Without prey, there would be no predators. Thus, this relationship is vital to the existence of life as we know it.

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DEFENSE MECHANISMS OF ANIMALS