All animals are besieged by danger. A brutal and merciless struggle is the only survival route in the animal kingdom. Many of us are aware of a few external organs of defence such as teeth, horns and claws among others. Many animals depend on muscular and internal power too. But another interesting thing is to have a spine on the body and to use the spine as a weapon for self-defence.

The spines are a remarkable anatomical structure seen in many shapes and sizes. Example is the porcupine quills, which can be more than a feet long in size, they can create trouble even for animals such as tigers and leopards. Following examples are even more interesting and fascinating to discover. The little Hedgehog has been quoted in a saying that “a fox knows many big tricks to survive, but a hedgehog knows only one amazing trick.” They have 5,000-6,000 quills on their outer shell. Looking at it, you may feel how uncomfortable its life is, but in reality, this is its only trick to survival. Whenever the hedgehog feels insecure in his environment, it would curl inside the spiny shell making it impossible for any predator to enter inside. The spines are pointed enough for any predator to leave the creature after little struggle.

Similarly, the spiny-tailed lizard, one of the most distinguishable lizards, is herbivore and has spines distinctively surrounding its tail, which act as a weapon for its safety. When a predator like raptors, monitor lizards or foxes would attack, the lizard would try and hit it with its spiny tail to get out of its catch. Also, it would keep the tail outside its burrow, so that its predators would not try to enter inside its hideaway. This is also a notable defence against other reptiles.

Coming to smaller micro fauna, the spider world has various mechanisms for survival. One of them is called the ‘sun spider’ as it has spines on its abdomen to prevent themselves from birds. Also for most small birds, it has a difficult shape to be swallowed easily. There are about 70-75 kinds of gastercantha spiders found in the world.

Most moths and caterpillars have hair and spines to prevent themselves from predators. However, they are mostly harmless. But there are some caterpillars, who do not like to be touched -- such as the stinging caterpillar. It has a mechanism wherein, if touched, the sting or hair would release toxins, which would enter the predator’s skin leading to burns, rashes and even nasty wounds. The spines like structures are actually stings, which serve the purpose when needed.

Next, we come to some birds like lapwings, which have interesting sharp claw-like structures, not on the foot but on the wings. Due to these structures only, their name was derived -- ‘Spur Winged Lapwing’. Although spurs in birds are common, but near the legs, birds like francolin, spur fowl among others, show interesting spurs. However, a unique bird like lapwing and jacana have them on their wings, which is used during a flight combat.

Just like plants have thorns, which protect them from external factors, many animals too, have evolved some mechanisms like spines to protect themselves.