Invertebrates:
Many Arthropods have mechanism for surviving temperature extremes.
Temperature zone insects avoid freezing by reducing the water content in their tissues as winter approaches. Other insects can produce glycerol or other glycoproteins that act as antifreeze. Some moths and humble bees warm up prior to flight by shivering contractions of their thoracic flight muscles. In most large flying insects blood circulating through the flight muscles carries heat from the thorax to the abdomen which gets rid of the heat. Certain cicadas that live in the Sonoran desert have cooling by evaporation like vertebrates.
When threatened with overheating, these cicadas extract water from their blood and transport it through large ducts to the surface of their body, where it passes through sweat pores and evaporates. In other words these insects can sweat. Porching dragonflies and butterflies can regulate their radiation heat gain by postural adjustments to sun. To prevent over heating many ground dwelling arthropods (beetles, locusts and scorpions) raise their bodies as high off the ground as possible to minimize heat gain from the ground. Some caterpillars and locusts orient with reference to both the sun and wind to vary both radiation heat gain and convective heat loss. Some desert dwelling beetles can exude waxes from thousands of tiny pores on their cuticle. These ‘wax blooms’ present dehydration and also are extra barrier against the desert sun.
Many black beetles may be more active earlier in the day because they absorb more radiation and heat faster. Conversely white beetles are more active in hotter parts of the day because they absorb less heat.
Fishes:
The temperature of the surrounding ater determines the body temperature of most fishes. Fishes that live in extremely cold water have “antifreeze” material in their blood. Poly alcohols (e.g. sorbitol, glycerol) or water soluble peptides and glycopeptides lower the freezing point of blood plasma and other body fluids.
These fishes also have proteins or proteins sugar compounds that stunt the growth of ice crystals that begin to form. These fishes stay flexible and swim freely in a super cooled. Some active fishes maintain a core temperature significantly above the temperature of the water. Blue fin tuna and great white shark have major blood vessels just under the skin. Branches deliver blood to the deeper, powerful red swimming muscles, where smaller vessels are arranged in a counter current heat exchanger called miraculous net. The heat that these red muscles generate is not lost because it is transferred in rete mirabile from venous blood passing outward to cold arterial blood passing inward from the body surface.
This arrangement of blood vessels enhances vigorous activity by keeping the swimming muscles several degrees warmer than the tissue near the surface of the fish. This system has been adaptive for these fishes. Their muscular contraction can have four times as much power as those of similar muscles in fishes with cooler bodies. Thus they can swim faster and range more widely.
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