Summer World_ A Season of Bounty - Bernd Heinrich [76]
Some desert animals similarly store water. The frog Cyclorana platycephala, from the northern Australian desert, fills up and greatly expands its urinary bladder to use as a water bag before burying itself in the soil, where it spends most of the year waiting for the next rain. While in the ground it sloughs off skin and forms around itself a nearly waterproof cocoon that resembles a plastic bag and reduces evaporative water loss.
Desert ants of a variety of species (of at least seven different genera) in American as well as Australian deserts collectively called “honeypot ants” have evolved a solution that combines water storage with energy storage. Ants typically feed each other; and some of the larger worker ants may take up more liquid than the others, and others may bring more. Those that take the fluid may gorge themselves until they distend their abdomens up to the size of a grape, by which time they are unable to move from the spot. They then hang in groups of dozens to hundreds from the ceiling of a chamber in the ant nest, where they are then the specialized so-called repletes that later regurgitate fluid when the colony members are no longer bringing the fluid in but rather needing it. In western North America about twenty-eight species of one genus, Myrmecocystus, have adopted the storage strategy of water and sugary secretions that are secured from aphids, flower nectar, and other plant secretions when summer is not yet too severe.
Animals’ solutions to the extremes of desert summer have also been exploited by people. In the Australian deserts the Aborigines have learned to find and access the water-holding frogs and use this resource as a last resort in times of need. In central Australia also the repletes of one honeypot ant species, Camponotus inflatus, are large enough to be commonly used by Aboriginal peoples. Those of Myrmecocystus mexicanus in the southwest in North America, who store water or honey or both, were also used by native peoples (Conway 2008). The Bushmen of the Kalahari Desert, instead of exploiting the fluid stores of frogs and ants, use the shells of ostrich eggs as containers for underground water storage caches; but as mentioned previously, when they exhaust these stores they resort to water stored by plants in underground tubers.
Fig. 32. The Apache cicada is active during the hottest part of the day in the summer, when most animals try to escape the heat.
For those who solve the water problem, the desert can be a haven. For peoples living in the American southwest, the Namib, and the Negev, the desert has often been a refuge from persecution. Under what circumstances except necessity would people be so ingenious and hardworking as to try to make the desert bloom and grow crops? Why would animals live where they are physiologically tested to the limits of their endurance? Where else except where they were severely tested would they evolve to extend their tolerances? The Apache cicada, Diceroprocta apache, of the Sonoran Desert of Arizona, is one such animal. It not only tolerates the severe summers there; it courts the heat.
As with the cicadas in New England, and those at numerous other places all over the globe, the larvae of the Apache cicada live underground, where they are relatively safe, and they could potentially emerge as adults