Does This Insect Actually Come Back to Life?

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Animals all over the planet have adapted to take full advantage of the habitats within which they live. However, the mountain stone weta (Hemideina maori) has one of the most extreme adaptive processes ever seen. As the fascinating clip above explains, this insect can survive being frozen solid over winter. It appears to die and then comes back to life as temperatures rise. Let’s take a look at the science behind this incredible ability.

What Are Mountain Stone Wetas?

The mountain stone weta is a large, flightless insect. It looks a little like its relative, the grasshopper. They are nocturnal and live in the alpine habitats of New Zealand. You will mostly find them in cavities under rock slabs, and their range covers the Kaikoura Ranges south to the Rock and Pillar range in Otago. There are also two island populations on Mou Waho Island and Mou Tapu Island. They mainly feed on plants but will occasionally eat invertebrates. Interestingly, they stay remarkably close to home and don’t wander far during their lifespan.

This is a harsh environment where temperatures can plummet and the winds are strong so only those animals that have adapted to low temperatures can survive.

Does the Mountain Stone Weta Actually Die and Come Back to Life?

No, this animal does not die in the cold conditions. Instead, it enters a sort of suspended animation where its metabolism slows down. If you find one in this state, you would be forgiven for thinking that it is dead, as it even has ice crystals on its cuticle. But on a warm day, it will revive and start moving around. They can survive for 17 days in this state and have tolerated temperatures as low as 14 degrees F.

How Do They Survive?

When it gets very cold, up to 85 percent of the weta’s body water turns into ice crystals. That’s higher than nearly any other animal known to science. Without available water inside their bodies, very few animals can survive. However, the mountain stone weta gets around this. As the clip above shows, their blood contains special chemicals called cryoprotectants, which their bodies produce in the fall in readiness for the winter. These include an amino acid (protein) called proline and tiny sugars called trehalose. The cryoprotectants work in a number of ways to protect cells, membranes, and delicate proteins from being damaged by ice crystals.

This does not just happen once. The weta can survive repeated freeze-thaw cycles, which is very useful considering the temperature fluctuations in the New Zealand mountain ranges.