A giraffe’s gir dark patches help it cool down
THERMAL BULLSEYE
Bees are experts at distinguishing different types of flower, and are capable of using colour, pattern and smell to help them collect nectar efficiently. But now it seems that temperature is also in their sensory toolbox, and they can distinguish 2°C temperature differences on a flower’s surface. Many flowers have distinctive patterns of temperature across their petals because of differences in solar heating and variations in the heat produced by the flower itself. A recent study used tiny hidden heaters to make patterns in flower ‘ targets’ and showed that bumblebees used those temperature patterns to identify the best flowers to visit.
GREENHOUSE GAS
We’re used to hearing about human-generated carbon dioxide contributing to the greenhouse effect, but the major greenhouse gas in Earth’s atmosphere is actually water. A planet’s temperature is determined by the balance between the incoming solar energy and the heat that’s radiated away. If our atmosphere didn’t contain any water, the energy flowing in and out would be balanced at an average temperature of -18°C. Water vapour in the atmosphere diverts some of the outgoing heat (via the greenhouse effect), and shifts the balance point to a far more pleasant 14°C. Human-generated greenhouse gases are now nudging the average temperature even higher.
SWEAT PATCH
In a hot environment like the African savanna, staying cool is essential for survival. And giraffes have several clever adaptations to prevent themselves from overheating. Their large nostrils allow them to lose huge amounts of heat via airflow, while the dark patches on their skin act as ‘ thermal windows’ from which heat can escape. Beneath each of those dark patches is an especially dense network of capillaries, and the skin itself contains enlarged sweat glands. On a hot day, blood can be redirected to the patches to be cooled efficiently by sweating, before returning to the heart.