Small Wonders: Arthropods With Superpowers
Robot designers know that making things big is easy, but making them small is hard. How do you pack a multitude of capabilities in a tiny space? Consider these little guys.
Tarantulas have eight eyes that are simple (like human eyes) instead of compound. Researchers found that they use their lateral eyes to calculate distance.
Lycosa tarantula, a wolf spider found in Spain, hunts by ambushing its prey and dragging its meal back to its 20cm-deep burrow. Finding the way back, however, can be a math problem after darting this way and that in the chase. Science Daily says it “uses path integration to return to its burrow.” Did this little creature ace trigonometry class? “With this mechanism, it does not follow the same path back to its burrow; instead, it moves as though it had followed the sides of a right-angle triangle, returning along the hypotenuse.” Scientists in Madrid ran experiments in the lab. It must have been fun trying to paint the lateral eyes shut on these speedy runners. The researchers put the spiders through their paces on specially-designed arrays of black and white bands. What they found reveals an astonishing array of instruments packed into a tiny space:
“To calculate the distance it has travelled, the animal needs an odometer that registers the route, its location with respect to the finish point, which would be the burrow, and a ‘compass‘ to track the direction of travel,” according to Joaquin Ortega Escobar, lead author of a paper published in the Journal of Experimental Biology on the function of each eye in these processes.
The ‘compass’ would correspond to polarised light, which the median eyes use to measure the angle; direction is detected by the anterior lateral eyes. Through this research, the scientists have learned that it is principally the anterior lateral eyes (which until now had not been analysed), and to a lesser extent the posterior lateral eyes, that help tarantula wolf spiders measures the distance to their nest.
Mosquitoes have some of the fastest wings in nature. Much as we despise them, we have to have a grudging admiration for a tiny creature that can flap wings 800 beats a second—four times faster than insects of a similar size. In Nature, Laura A. Miller describes efforts to understand the flight mechanics of mosquitoes (many species of which do not bite humans). Despite the fast wingbeats, which make that annoying whine, the thin wings only employ strokes of about 40° in amplitude—much shorter than in other flying insects. Science Daily says that the researchers at Oxford University, curious about the narrow wings and short beats, “predicted that they must make use of clever tricks as the wings reverse their direction at the end of each half-stroke.”
How can a tiny brain of less than a million neurons achieve complex processes?
In particular, the researchers wondered how they get enough lift. Even a mosquito needs lift to fly. The answer, they found with cameras running at 10,000 frames a second, was by a rotation mechanism in the wing attachment muscle that induces vortices on both forward and backward strokes, gaining lift in both directions. This sounds similar to what Illustra Media demonstrated in far larger animals, hummingbirds (see Flight: The Genius of Birds). Miller compares it to the force one feels holding a hand out the window of a moving car, rotating it into and out of the wind. The researchers (who must have had amazing technology to measure lift on such minuscule wings) found that mosquitoes actually employ three mechanisms to get all the lift they can: (1) leading-edge vortex, (2) wake capture, and (3) rotational drag—a trick unique to mosquitoes.
Could drone designers learn from these tricks of the mosquito? “Mosquito-flight investigations are certainly on their way to generating plenty of future research buzz,” Miller quips.
Honeybees have better eyesight than thought, Science Daily reports. They can clearly discern objects at angles of a mere 1.9°, as small as your thumb at arm’s length, but that’s not all; they can make out objects at just 0.6° almost as well, a third as wide. This is 30% better than earlier thought, according to an Australian team that gave eye tests to bees.
“Among other things, honey bees help to answer questions such as: how can a tiny brain of less than a million neurons achieve complex processes, and what are its utmost limits? In the last few decades it has been shown that bees can see and categorize objects and learn concepts through vision, such as the concept of ‘symmetric’ and ‘above and below’….
“Photoreceptors in the visual system detect variations in light intensity. There are eight photoreceptors beyond each hexagonal facet of a bee’s compound eye, and their eyes are made out of thousands of facets!“
Butterflies have an amazing mouthpart called the proboscis that lets them slurp nectar like drinking through a straw. Only they don’t need to suck; the proboscis is designed to bring fluid in automatically, by capillary action. These mouthparts are clearly shown in Illustra Media’s documentary Metamorphosis, which shows how after hatching from the chrysalis, the proboscis emerges in half-channels. The butterfly uses other mouthparts called palpi to knit the two halves together into a single channel. The proboscis can be rolled up into a neat little circle like a hose reel, and extended for use.
Recently, Phys.org tried to unravel other mysteries of the mouthparts of butterflies. And like the “bee team” reported above, researchers at Kent State (UK) wanted to learn about this to imitate it. “An insect’s proboscis, a body part that allows them to drink liquids, acts like a highly-sophisticated sponge and straw that uses capillary action to send nectar or other liquids to the insect’s digestive system,” the team says. The channel size is crucially important for the type of liquid the insect needs to drink.
The team’s findings show that capillary action is an essential and ideal method for removing small amounts of fluids from surfaces, Lehnert said. By copying this natural method, scientists say the mouthparts of flies and butterflies can serve as models for developing new devices for improved drug delivery systems.
Even though engineers can only approach the efficiency of the butterfly proboscis, Lehnert attributed the insect’s design to evolution. “In order to feed on nectar and other liquid films, natural selection has favored the evolution of specialized mouthparts in fluid-feeding insects,” the press release writer says. Then Lehnert mixes convergent evolution with personification to portray natural selection as a refining agent:
“It was previously known that flies and butterflies independently evolved mouthparts adapted for feeding on fluids, but what was unknown before our study was that they both use the same principles for ingesting fluids – capillary action,” Lehnert said. “Our findings have applications to the production of novel microfluidic devices that can be developed to mimic the functionality of insect mouthparts, which have the advantage of being impacted by natural selection over millions of years.“
Ants rescue their dead. Did you know that? Neither did scientists; Phys.org reports that researchers in Europe, studying African ants, didn’t expect to see this. “We have observed helping behaviour vis-à-vis injured animals for the first time in invertebrates,” one said. For social insects where nest members are clones with no individuality, this is quite amazing; “obviously, it pays off for the colony as a whole to invest in the rescue service,” they say. The ants’ triage service will sound remarkably familiar to those in the human military:
When an ant is injured in a fight, it will “call” its mates for help by excreting chemical substances. The injured insect is then carried back to the nest where it can recover after receiving treatment. What is the “therapy” like? Usually, treatment involves removing the termites still clinging to the ant.
Dung Beetles seem disgusting, rolling balls of poop around to feed on, but they actually play a part in the balance of nature. And they have an amazing trick that has come to the light of science: they navigate by the Milky Way. Really! At The Conversation, James Foster of Lund University describes experiments to figure out how they do it. His team created an artificial Milky Way sky to watch them under controlled conditions. They found that it isn’t constellations that guide them, but the brightness patterns between the Milky Way and the other parts of the sky that help them orient themselves, so that they can roll their ball in a straight line.
This brightness-comparison strategy may be less sophisticated than the way birds and human sailors identify specific constellations, but it’s an efficient solution to interpreting the complex information present in the starry sky—given how small the beetles’ eyes and brains are. In this way, they overcome the limited bandwidth of their information processing systems and do more with less, just as humans have learnt to do with technology.
So there you have it: insects and arachnids with remarkable superpowers, using well-designed equipment. The genius in these animals is so good, scientists study it in order to copy it. Knowing what we have learned, it makes it hard to swat, step on, or spray these sophisticated little living robots.
Don’t feel too sorry for that mosquito after your blood. This is not the “very good” world of the original creation before the Fall. Still, God has left enough evidence of his creative power to stand in awe of his wisdom. It should draw us to seek him, humble ourselves, repent, and trust in his way of escape from the consequences of sin.