Larvae Survive Freezing

close up photograph of insect larvae on a log

Biological Strategy

Midge

AskNature Team

Image: Katja Schulz / Flickr / CC BY - Creative Commons Attribution alone

Protect From Ice

Freezing temperatures can be difficult for living systems to manage. They can cause ice crystals to form in blood and tissues, which causes damage to cells and ultimately, death. Living systems can’t afford the energy required to melt ice crystals, so instead, many have strategies to prevent crystals from forming in the first place. Many amphibians, plants, and insects have chemicals that act as antifreeze to prevent icy crystal formation. Another challenge ice presents is that it creates a slick surface, requiring friction to traverse. This is why polar bears’ paws have a rough surface that grips ice.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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Larvae of midges survive freezing by having a high supercooling point.

“Certain insects, moreover, can even survive the formation of ice crystals within their bodies. One example is the larva of the midge Chironomus, which can be repeatedly frozen to a temperature as low as -13°F (-25°C), up to 90 percent of its body fluid is frozen. Such creatures are said to be freezing-tolerant.” (Shuker 2001:110-111)