Ask Dr. Universe: What Did Praying Mantises Evolve From?

Washington State University

Dr. Universe: What did praying mantises evolve from? – Tara, 12 years old

Dear Tara,

When you think of the Jurassic period, you might think of dinosaurs, but all kinds of insects, including praying mantises, also roamed the Earth back then.

Some mantises died and became fossilized in rock and amber, which helped preserve them for hundreds of millions of years. As scientists uncover these fossils in modern times, they can learn more about the life history of insects.

That’s what I learned from my friend Elizabeth Murray, an entomologist at Washington State University, who was very curious about the diversity of insects on our planet.

She said that in addition to fossils, scientists sometimes study insect DNA, or their genetic material, to learn more about how insects evolved and what ancestors they might have in common.

If you’re like me, you might be surprised to learn that mantises share a common ancestor with another well-known insect.

“We have evidence that comes together and shows that cockroaches and mantids are most closely related,” Murray said. “They had a common ancestor that maybe even looked like a mix of the two bugs.”

Like many insects, cockroaches and mantises have six legs and three main body segments. Not only do they share a genetic history, but they also lay their eggs the same way. Cockroaches and mantises make a special case for protecting their eggs.

The ability to build a sturdy egg box, or what scientists call an ootheca, helps give insects an advantage as they protect their tiny eggs from hazards like pests, predators and the weather.

Over hundreds of millions of years, the traits and abilities that help different insects survive have been passed down from parents to their offspring.

Murray reminded me that when we talk about how an insect evolves, we are talking about all those changes that occur in a species through millions of generations.

Scientists are still learning more about the history of praying mantises and are even discovering species that lived in the past.

Last year, researchers reported their findings of a fossil that helped them identify a previously unknown species of praying mantis. This praying mantis lived about 100 million years ago at the end of the Cretaceous.

By using modern imaging tools and computer models, scientists can help identify differences and similarities between species that existed millions of years ago and species that exist now. This helps to paint a better picture of the insect family tree.

It is also a fairly large tree. Murray told me that there are at least a few million known species of insects, but according to some estimates there could be 10 million species of insects on our planet.

Maybe one day you can study to become an entomologist and help us learn more about different species of insects. The next time you see a cockroach or praying mantis, think about how they share a common ancestor — and as always, keep asking good questions.

Truly,

Dr. Universe

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