Evolutionary arms race is a term used to describe escalating adaptations and counter-adaptations between certain predators and preys. When one evolves an adaptation to better defend or attack, it is countered by an even more effective adaptation that cancels out that initial adaptation. This back and forth continues on and on and on and on…

An example of an arms race between a crab and its prey, a snail.

Here on Catalina, where resources are scant and evolution moves quickly, we have our very own evolutionary arms race that has intensified. The battle is between the ground squirrel and the rattlesnake, with the ground squirrel in the ‘Prey’ corner and the rattlesnake in the ‘Predator’ corner.

A Catalina Island rattlesnake basks in the sun, contemplating how to defeat its nemesis, the ground squirrel.

Our battle starts off with the rattlesnakes’ initial strike…. Due to the isolation of the island, the rattlesnakes here have evolved intensified venom to more easily subdue their prey. In response, however, the adult squirrels have gained the ability to neutralize venom. So, in turn, the snakes began to then target only juvenile squirrels who have not yet developed strong enough resistance. But the squirrels had something remarkable up their sleeve…. The ground squirrel began to use the snake’s amazing infrared vision against it! Usually the snake can sense heat to more easily find these juvenile squirrels. Using this to their advantage, the squirrels began to throw dirt at the snakes’ eyes and shake their tails high above their body, producing heat and making themselves seem much larger and more intimidating! Adult squirrels have also been known to eat snake skin and lick their offspring to mask their scent!

A ground squirrel contemplates its place in the universe, and how to ultimately defeat its arch enemy, the rattlesnake.

Time will only tell where this amazing evolutionary battle continues to go and who comes out on top!

 

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