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a brown pseudoscorpion photographed on a black background, its long claw like arms are red and its entire body is covered in small hairs

Biological Strategy

Pseudoscorpion

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Image: Yellowstone National Park / Wikimedia Commons / Public Domain - No restrictions

Move in/Through Gases

Living systems must move through gases (which are less dense than liquids and solids) such as those in the earth’s atmosphere. The greatest challenge of moving in gases is that because the living system is heavier than the gas, it must overcome the force of gravity. Moving efficiently in this light medium presents unique challenges and opportunities for living systems. As a result, they have evolved countless solutions to optimize drag and increase lift so that they can stay aloft and take advantage of variable currents. Additionally, they must overcome gravity when moving from a liquid or solid into the air. The fairyfly, the smallest known insect, is a tiny wasp that must move through the air. To the wasp, air feels like a heavy liquid and to move through it, it uses special feathery oars rather than wings.

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Adapt Behaviors

The environment is constantly changing, and if living systems can’t adapt to these changes, they don’t survive. Environmental changes can be cyclic such as seasons, sudden such as floods or forest fires, or gradual but long-term, such as ecosystems shifting from early to mature stages. These changes require some flexibility in behavioral responses to match the specific conditions. For example, as a fish called the lamprey swims, it constantly faces changes in currents. Skin sensors help it detect those changes and adjust its motion accordingly.

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Optimize Shape/Materials

Resources are limited and the simple act of retaining them requires resources, especially energy. Living systems must constantly balance the value of resources obtained with the costs of resources expended; failure to do so can result in death or prevent reproduction. Living systems therefore optimize, rather than maximize, resource use. Optimizing shape ultimately optimizes materials and energy. An example of such optimization can be seen in the dolphin’s body shape. It’s streamlined to reduce drag in the water due to an optimal ratio of length to diameter, as well as features on its surface that lie flat, reducing turbulence.

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Arachnids

Class Arachnida (“spider”): Spiders, mites, ticks, scorpions

Arachnids get a bad reputation, but they play an important role in the ecosystem by controlling insect populations. Almost half of the species in the class are spiders, and most live in terrestrial environments. Unlike insects, most arachnids have two body sections: the cephalothorax, which is the head and thorax fused together, and the abdomen. Mites and ticks, on the other hand, have only one body section that is relatively flat. This body shape comes in handy for the species that are parasitic, because it makes it harder for their hosts to bite or scratch them off.

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One species of pseudoscorpion fights for mating privileges while emigrating to a new tree on a harlequin beetle.

“A beetle’s belly may seem an unlikely place for a sexual playground, but that is precisely what it is for the pseudoscorpions of Central and South America. These creatures make their homes in the wood of decaying fig trees. They travel to fresh trees by hitching a ride under the wings of a giant harlequin beetle. But a free ride is by no means all that pseudoscorpions get from their beetle host. In flight, they use the beetles as a mobile mating ground, pursuing the objects of their desire back and forth across the beetle’s abdomen.

“David Zeh and Jeanne Zeh of the Smithsonian Tropical Research Institute in Panama have studied this peculiar relationship between beetle and pseudoscorpion (Cordylochernes scorpioides). They discovered that as harlequin beetles (Acrocinus longimanus) emerge from the rotting wood of fig trees, they attract scores of pseudoscorpions eager to be flown to newly rotting trees (Behavioral Ecology and Sociobiology, vol 30, p 135). ‘Both males and females compete to board the beetles,’ say the researchers.

“Most of the emigrating females are sexually receptive, so males are intensely keen to retain a toehold on the beetle’s belly. As the beetle flies towards its destination, in search of mates or trees suitable for egg-laying, the male scorpions on its belly fight among themselves to establish ‘mobile mating territories’. The bigger males fare best in the competition, shoving smaller males off the beetles before mating, say the Zehs.” (Vines 1992)

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