Some scientists theorize that high oxygen levels during the Paleozoic era allowed dragonflies to grow to monster size. There are more than 5,000 known species of dragonflies, all of which (along with damselflies) belong to the order Odonata, which means “toothed one” in Greek and refers to the dragonfly’s serrated teeth.

In their larval stage, which can last up to two years, dragonflies are aquatic and eat just about anything—tadpoles, mosquitoes, fish, other insect larvae and even each other.

At the end of its larval stage, the dragonfly crawls out of the water, then its exoskeleton cracks open and releases the insect’s abdomen, which had been packed in like a telescope. Its four wings come out, and they dry and harden over the next several hours to days.

Dragonflies catch their insect prey by grabbing it with their feet. They’re so efficient in their hunting that, in one Harvard University study, the dragonflies caught 90 to 95 percent of the prey released into their enclosure. Some adult dragonflies live for only a few weeks while others live up to a year.