Sometimes science does really cool things. Take a hypothesis, for instance. It's an explanation for an observed phenomenon. But to be proven, hypotheses have to be tested, and sometimes it's during this investigation that scientists end up proving something else entirely.
That's what happened with the elusive insect the orchid mantis, who had a few tricks up her sleeve scientists weren't aware of.
What Is an Orchid Mantis?
Orchid mantises, Hymenopus coronatus, live in the rainforests of Southeast Asia. The females are big, measuring 2.3 to 2.7 inches (6 to 7 centimeters) long compared to their male counterparts only 0.7 to 1.1 inches (2 to 3 centimeters) long.
Since their discovery more than 100 years ago, it was thought these floral mantises evolved to their beautiful pink and white colors and wide flat legs to imitate orchid flowers and confuse prey. Then, they sneakily attack insects like moths, butterflies, beetles, or even frogs and scorpions. This type of evolution is called cryptic mimicry or cryptic coloration and can be used for defensive or aggressive purposes. Other insects, such as the leaf-life katydid, do it too.
It makes sense, right? That's what scientists thought until a few years ago a group of researchers decided to put that hypothesis to the test.
In 2014, scientists did systematic field testing to see how adult female orchid mantises operated. Turns out, they don't use camouflage at all. In fact, insects were attracted to the orchid mantises more than any flower. The insects were already beelining toward them without the need for camouflage.
If not cryptic mimicry, why did the mantises evolve this way?
Why Do They Look Like Orchids?
By evolving to be larger and more flower-like, female mantises increase their chances of attracting their preferred prey. It's called aggressive mimicry. They don't look like one flower. Research shows that their color evolved to imitate several species of flowers.
James Gilbert, an insect evolutionary biologist, explained it to The Conversation from a insect's perspective that the color from a distance says to it's brain "delicious nectar here." As the insect approaches the orchid mantis, the petal-shaped legs confirm what the insect thinks to be true — it's a flower. Insects don't have developed brains like ours, their lives are short and they have no critical thinking skills. So naturally, the insect gets trapped, eaten and the circle of life continues, for the orchid mantis, at least.
Why is this so cool to scientists? A 2016 study led by Gavin Svenson of the Cleveland Museum of Natural History (CMNH) says it's important for a few reasons.
First, it's one of the first times that a female adaptation in a species has been for predatory purposes, not reproductive ones. Sexual dimorphism is when a male and female of the same species evolve differently. Usually, the adaptations are both for reproductive purposes.
In the case of adult female orchid mantises, they adapted because they were hungry, not to improve their chances of having babies. Their male counterparts are smaller and do camouflage to avoid being eaten, thus increasing their chances of mating.
Second, this type of study highlights how systematic field research can help reveal patterns in evolution we haven't noticed previously. Svenson's study wasn't looking at orchid mantis evolution specifically. But after he and his team noticed patterns in their data, they began thinking maybe there was more to the story. CMNH reports that for scientists like Svenson, this kind of discovery is the "holy grail" of systematic research.
And finally, the orchid mantis is the first animal known to mimic an entire flower (color, petals, etc.), not just part of it, to attract insects of its own accord.
Once again, animals prove that we can't always predict why they do what they do or look how they look. Mother Nature continues to surprise us in beautiful and deadly (if you're a bug) ways!