March 21, 2017 | David F. Coppedge

Clever Critters

Small animals accomplish mighty wonders that require knowledge of advanced mathematics, physics and genetics.

Moths: How do insects see in the dark? Some moths and bees get by with only a few photons – they seem to defy what is physically possible, remarks Erik Warrant, professor of zoology at Lund University, in The Conversation. He studied hawkmoths, dubbed the “hummingbirds of the insect world” because of their bright colors. The moths are able to perform summation on photons similar to keeping the shutter of a camera open longer in order to collect more light. The method sacrifices acuity, but works well enough to find a mate, avoid a predator or get by. “In fact,” Warrant says, “thanks to these neural mechanisms, Deilephila can see at light intensities around 100 times dimmer than it could otherwise.”

Fruit flies: These tiny dipteran insects make use of a property called ‘optic flow’ in their aerobatic feats. Current Biology says that fast flight introduces photon noise and lowers the signal-to-noise ratio as much as darkness does. To solve this, flies employ a trick called ‘facultative summation,’ described by Jamie Theobald:

Amazing FactsPhotoreceptors need quick temporal dynamics to cope with fast motion, so the ideal filtering would additionally be spatial. To determine if fruit flies implement filtering driven by background optic flow, I tested their frequency-dependent steering and found that flow transiently eliminates high spatial frequency responses. This effect increases from forward to lateral visual regions, acts only parallel to flow direction, and filters only high spatial, not temporal, responses. Facultative summation may maximize visual information by improving sensitivity during fast flight, but limiting acuity loss when the fly is still.

Tardigrades are able to survive long periods of dessication. Live Science explains how they do it maintaining a special supply of unique ‘intrinsically disordered proteins’ or TDPs. “TDPs protected the tardigrades in much in the same way that trehalose [a sugar] protects other animals, by forming glass-like structures that help to preserve cells that are in a dehydrated state.”

Birds and mammals need to keep track of the seasons to know when to grow more feathers and fur, reproduce, and carry on other vital functions of life. PhysOrg describes how scientists at the University of Bristol monitored secretions of the hormone melatonin in sheep. Produced at night, melatonin triggers other enzymes and genes depending on length of the daylight. This affects blood vessels near the pituitary gland and also signals different parts of the pituitary gland that control functions like fertility.

Who taught these small animals these tricks? Performing these feats require technology aware of quantum mechanics and calculus. They involve advanced optics, information technology, and biomechanics. A country bumpkin has enough sense to know what’s going on: “Someone’s running this concern that ain’t got nothin’ else to learn.”


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