Belgica antarctica, the Antarctic midge, is a species of flightless midge, endemic to the continent of Antarctica. At 2–6 mm (0.079–0.24 in) long, it is the largest purely terrestrial animal native to the continent.[2][3] It also has the smallest known insect genome as of 2014, with only 99 million base pairs of nucleotides (and about 13,500 genes). It is the only insect that can survive year-round in Antarctica.[4][5]
| Belgica antarctica | |
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| Two Belgica antarctica adults | |
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| Species: | B. antarctica |
| Binomial name | |
| Belgica antarctica | |
The flightlessness of B. antarctica may be an adaptation to prevent wind from blowing it into inhospitable areas.[3] It can survive freezing, but though local air temperatures may reach as low as −40 °C, this insect cannot survive temperatures below −15 °C. This is comparatively milder than other cold-adapted insects. The reason for this relatively low freezing tolerance is due to thermal buffering: just burrowing at a depth of 1 cm, temperature is stable between 0 and −2 °C for 10 months out of 12, and it seldom goes lower than −7 °C all year round. Ice and snow cover also helps keeping the temperature stable.[6] Freezing tolerance is enhanced by cold hardening.[6]
To adapt to the cold temperatures, B. antarctica accumulates trehalose, glucose, and erythritol. These compounds help the insect survive freezing by reducing the amount of ice that forms within the body. They also stabilize proteins and membranes, binding to them by means of hydrogen bonds. Heat shock proteins also help the tolerance to both high and low temperatures.[7]
B. antarctica not only tolerates, but also requires a freezing climate to survive: exposure of larvae to such mild temperatures as 10 °C is enough to kill them within a week.[6] Exposure to temperatures of 30 °C kills individuals in a few hours.[7] It can, however, resist partial desiccation, surviving the loss of up to 70% of body water.[7]
https://en.wikipedia.org/wiki/Belgica_antarctica
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