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If it Looks Like an Ant and Smells Like an Ant... Batesian Mimicry in the Amazon Jungle

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Over 150 years ago, in the steamy jungle of the Amazon Rainforest, the explorer and naturalist Henry Walter Bates was watching two different butterflies fly side-by-side. He had discovered that one was poisonous, which would make any predator sick if it was eaten. He also knew that the other lacked any poison defense.

The reason Bates was watching them so closely was that, despite being different species and only one being poisonous, the butterflies looked almost exactly alike.

In the animal kingdom, it is s best to advertise you are poisonous before the predator has to eat you to find out, for obvious reasons. This is why many poisonous animals advertise their defenses with bright coloration. Predators then quickly learn to beware of certain patterns and combinations of colors. But of course, this only works if the animal is actually poisonous.

So, what about our non-poisonous butterfly? Well, this is exactly what Bates was thinking as well.

His theory was that the harmless species wanted to trick predators into thinking it was also poisonous. And he was right.

Now a well-known phenomenon, Batesian mimicry (named after Bates) is when a non-harmful species copies the appearance of a harmful species. These non-harmful mimics trick predators into avoiding them as well, without needing to be poisonous or otherwise harmful themselves.

The most familiar animals we know of that mimic other species in this way include hoverflies that imitate wasps and bees, milk snakes that are patterned like venomous coral snakes, and certain caterpillars that seem to resemble snake heads.

But some species that are great models for mimicry, because of their harmful nature to would-be-predators, don’t have actually have showy and colorful appearance.

 

Peruvian tropical rainforest ant-mimicking spider Myrmarachne

Ant-mimicking jumping spider (Myrmarachne sp.) from Tambopata Reseach Center photographed by Paul Bertner.

Ants, for example, are often a dominant insect in an environment. With their vast numbers, biting jaws, and painful stings, many animals quickly learn to stay out of an ant’s way or else face the threat of the colony.

Even the Biblical Solomon recognized the benefit of copying ants. He exclaimed, “Go to the ant, thou sluggard. Consider her ways and be wise.” - Proverbs 6:6

And some species have had this very idea.

Many different bugs and spiders are now known to look like ants. By doing so, they trick their would-be-predators into avoiding them for fear of being attacked by the colony. For example, a well-studied genus of jumping spider is so good at ant-mimicry that the entire genus was named Myrmarachne. Myrm is from the Greek word for ant (think of the Myrmidons led by Achill

es in Greek mythology, resembling ants as they swarmed the beaches), and arachne from the Greek word for spider.

Just as Solomon was referring to an ant’s behavior, we now know that animals not only mimic the ant’s appearance, but also how they hold their antennae and how they move.

This is all very well and good if you want to trick visual predators into thinking you’re an ant. But what if you wanted to trick the ants themselves?

Although some ants are quite visual, most ants live in a world dominated by smells, which are known as pheromones. If they encountered an animal that simply looked like an ant but didn’t smell like an ant, the con-artist would quickly be discovered.

 

Ant-mimicking clubionid spider (Myrmecium sp.) from Tambopata Research Center

An ant-mimicking clubionid spider (Myrmecium sp.) from TRC. Photograped by Paul Bertner.

It just so happens that some mimics trick the ants themselves instead of potential predators. These species may not look like an ant to you or me, but to an ant investigating the stranger, they are accepted as a member of the colony. These species have managed to fool the ants by copying their chemical pheromones.

But why, you ask?

Unfortunately for the ants, animals often want to trick them in order to gain valuable access to the nest to eat their eggs, such as some members of the spider genus Cosmophasis. Other species copy the ant pheromones to create an army of duped ants protecting and caring for the mimic’s every need, as is the case for certain Lycaenid butterflies.

You can see the colorful butterflies, jumping spiders, ants, and the mimics in Peru’s remarkable Tambopata National Reserve.

So remember, things may not always be as they seem in the wonderful world of biodiversity. If it looks like an ant, smells like an ant, or behaves like an ant, it might just be a spider...

 

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