Origin of Venom

             Venom is a widely used trait among the animal kingdom.  It has gone through convergent evolution throughout the animal kingdom.  Convergent evolution is when the same trait evolves for the same reasons, but in completely different lineages.
             Many animals use venom either to hunt or to protect themselves from predators.  "Venom is the mark of a special club, a select subset of the animal kingdom. It includes vipers, jellyfish, spiders, scorpions, centipedes, bees, cone snails, newts, platypus, and even a primate" (Zimmer).  Venom is made up of molecules specifically designed to harm another animal.  There are two types of venom, neurotoxins and  hemotoxins.  A neurotoxin is designed to break down the nervous system and the brain, causing a swift death in many animals.  A hemotoxin is designed to break down blood cells and organs, causing a slow and painful death.

 

            All the animals containing venom evolved this unique trait completely separate, but only for two main reasons.  They all evolved venom to either hunt prey or defend from predators.  Snakes, scorpions, and spiders developed venom to both hunt and defend themselves.  The black widow spider has one of the most potent venoms in the animal kingdom, but it cannot inject larger animals (such as humans) with enough venom to cause immediate fatality.  Many other animals like poison dart frogs, puffer-fish, and even some mammals developed venom to protect themselves from predators.  The poison dart frog has a unique, bright colored pattern to warn predators that its skin is highly toxic.

            Venom is a highly unique trait, but it is extremely advantageous to many different animals all throughout the animal kingdom. 

http://phenomena.nationalgeographic.com/2013/01/09/on-the-origin-of-venom/