Shivering Muscles Produce Heat

close up portrait of yellow and black bumblebee with longer fuzz

Biological Strategy

Bumblebee

AskNature Team

Image: Arnstein Staverløkk / Wikimedia Commons / CC BY SA - Creative Commons Attribution + ShareAlike

Transform Mechanical Energy

Mechanical energy is made up of kinetic energy (the energy of an object in motion) and potential energy (stored energy). Organisms use mechanical energy in a variety of ways, including capturing prey, transporting seeds, and moving around.

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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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The thoracic flight muscles of Arctic bumblebees generate heat by shivering.

“The major cold weather adaptations of bumblebees in general, and of the arctic bees in particular, however, are the mechanisms that allow them to raise their body temperatures and to be active when the weather forces other insects into a deep torpor. The shivering of their flight muscles generates heat in the thorax up to 60 degrees F above the air temperature. Like all other bumblebees so far investigated, arctic bumblebees require a flight muscle temperature of at least 86 degrees F in order to fly. But flight is clumsy at such muscle temperatures, and fast-flying bees need to heat up to at least 95 degrees F. Being able to shiver, to heat up, and to fly so early in the season means being able to go out and bring back nectar and pollen to the colony. This allows colonies to grow during the cold nights as well as during the days.” (Heinrich 1990:52)