Baby boxers

Written by      

Richard Robinson

The mantis shrimp subdues its prey by punching it with a blow that’s strong enough to crack a glass aquarium and generates enough heat to boil water. So when do baby mantis shrimp develop this super-smash prowess?

To find out, Duke University researcher Jacob Harrison headed to Hawai‘i with a high-speed camera in search of Gonodactylaceus falcatus larvae—one of the world’s 450 species of mantis shrimp.

First, he had to catch a four-millimetre-long larva. “It can be incredibly challenging to sift through a bucket teeming with larval crabs, shrimp, fish and worms to find the mantis shrimp,” says Harrison.

Then he had to position the larva in front of his high-speed camera—a task that ended up taking a year to perfect (and involved supergluing the larva to a toothpick).

But the effort was worth it. The high-speed footage revealed the mantis-shrimp punch in action: the limb bending back like a spring, before a tiny latch is released that flings the appendage forward with impressive acceleration and speed—around 38 centimetres per second. While the larva was slower than full-grown adults, the jabs were still five to ten times faster than the swimming speed of similar-sized organisms, and 150 times speedier than their prey.

After raising some larvae from eggs, Harrison observed that they first began to hunt with their forelimbs between the ages of 9 and 15 days.

Although young mantis shrimp go through six to seven transformations from hatching to fully grown, Harrison’s footage showed that the spring-and-latch mechanism is the same in young and old. And while the larva’s punch may be scaled down, the transparent exoskeleton of larvae revealed remarkable detail previously unseen: the tiny muscles contracting as the mantis shrimp wound up for another devastating blow.

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