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Wise Oysters, Galloping Sea Stars, and More: Biological Marvels Keep Coming

Evolution News

Strong theories in science require fewer auxiliary hypotheses when new discoveries come to light. Design advocates can gain confidence when discoveries continue to illustrate the core principles of intelligent design, like irreducible complexity, meaningful information, and hierarchical design, while undermining the blind, gradualistic principles of Darwinian evolution. Here are some recent illustrations.

“Pearls of Wisdom”

That’s the headline on news from the Okinawa Institute of Science and Technology, where the only thing said about evolution is that “From a genetic and evolutionary perspective, scientists have known little about the source of these pearls” in the Japanese pearl oyster, Pinctada fucata. By implication, don’t look for pearls of wisdom from evolutionary theory. The research published in Evolutionary Applications only concerns genetic variations within the species and the geographic distributions of isolated populations. If it helps conserve these oysters with their magnificent mother-of-pearl nacre — the envy of materials scientists — well, it’s wise to keep jewelry makers in business. Design scores as evolution fumbles.

Flight Feathers

Another level of design has been uncovered in bird feathers. In Science Magazine, Matloff et al. discuss “How flight feathers stick together to form a continuous morphing wing.” Pigeon and dove wing feathers spread out from their folded position into beautiful fans, as most people know. But how do birds prevent gaps from opening up between individual wing feathers? The team found a combination of factors at work. 

Birds can dynamically alter the shape of their wings during flight, although how this is accomplished is poorly understood. Matloff et al. found that two mechanisms control the movement of the individual feathers. Whenever the skeleton moves, the feathers are redistributed passively through compliance of the elastic connective tissue at the feather base. To prevent the feathers from spreading too far apart, hook-shaped microstructures on adjacent feathers form a directional fastener that locks adjacent feathers.

Notice that the muscles, bones, and connective tissue inside the skin work in synergy with the exterior hooks on the wings. Using a robot mimic, the team found that (1) the muscles for each feather keep the angle just right to spread them into a fan arrangement, and (2) the barbules snap together quickly to create a lightweight, flexible surface without breaks. The barbules can quickly detach like the hook-and-loop materials we are all familiar with.

This clarifies the function of the thousands of fastening barbules on the underlapping flight feathers; they lock probabilistically with the tens to hundreds of hooked rami of the overlapping flight feather and form a feather-separation end stop. The emergent properties of the interfeather fastener are not only probabilistic like bur fruit hooks, which inspired Velcro, but also highly directional like gecko feet setae — a combination that has not been observed before.

Rapid opening and closing of wings makes a little bit of noise a bit like Velcro does, explaining the din when a flock of geese takes off. Interestingly, the researchers found that night flyers like owls, which need silent wings as they hunt, “lack the lobate cilia and hooked rami in regions of feather overlap and instead have modified barbules with elongated, thin, velvety pennualue” that produce relatively little noise. Otherwise, this amazing complex mechanism works at scales all the way from a tiny 40-gram Cassin’s hummingbird to the 9000-gram California condor. What’s an evolutionist going to say about this ingenious mechanism? Once upon a time, a dinosaur leaped out of a tree and… died.

Distributed Running

Sea stars, seen in time-lapse videos, appear to “run” across the sea floor, bouncing as they go:

Scientists at the University of Southern California wondered how the echinoderms do it without a brain or centralized nervous system. The undersides of sea stars are composed of hundreds of “tube feet” which can move autonomously. How do they engage in coordinated motion? 

The answer, from researchers at the USC Viterbi School of Engineering, was recently published in the Journal of the Royal Society Interface: sea star[s] couple a global directionality command from a “dominant arm” with individual, localized responses to stimuli to achieve coordinated locomotion. In other words, once the sea star provides an instruction on which way to move, the individual feet figure out how to achieve this on their own, without further communication.

That would be a cool strategy for robots, the engineers figure. In fact, they built a model based on sea star motion, and show both the animal and robot movement side by side in the video above. No other animal movement seems to use this strategy. 

“In the case of the sea star, the nervous system seems to rely on the physics of the interaction between the body and the environment to control locomotion. All of the tube feet are attached structurally to the sea star and thus, to each other.”

In this way, there is a mechanism for “information” to be communicated mechanically between tube feet. 

Even though one of the team members was a “professor of ecology and evolutionary biology,” he seemed to rely more on the engineers than on Darwin. 

Understanding how a distributed nervous system, like that of a sea star, achieves complex, coordinated motions could lead to advancements in areas such as robotics. In robotics systems, it is relatively straightforward to program a robot to perform repetitive tasks. However, in more complex situations where customization is required, robots face difficulties. How can robots be engineered to apply the same benefits to a more complex problem or environment?

The answer might lie in the sea star model, [Eva] Kanso said. “Using the example of a sea star, we can design controllers so that learning can happen hierarchically. There is a decentralized component for both decision-making and for communicating to a global authority. This could be useful for designing control algorithms for systems with multiple actuators, where we are delegating a lot of the control to the physics of the system — mechanical coupling — versus the input or intervention of a central controller.”

Once again, the search to understand a design in nature propels further research that can aid in the design of products for human flourishing.

Quickies:

Grasshoppers don’t faint when they leap. Why? Arizona State wants to know how the insects keep their heads while taking off and landing in all kinds of different orientations. Gravity should be making the blood slosh around, causing dizziness and disorientation, but it doesn’t. Apparently it has something to do with the distribution of air sacs that automatically adjust to gravity, keeping the hemolymph (insect blood) from rapidly moving about in the head and body. “Thus, similar to vertebrates, grasshoppers have mechanisms to adjust to gravitational effects on their blood,” they say.

Cows know more than their blank stares indicate. Articles from Fox News and the New York Post had fun with a “shocking study” about “cowmoooonication” published in Nature’s open-access journal Scientific Reports. Experiments with 13 Holstein heifers seem to indicate that they all know each other’s names, and can learn where food is located, and more, from each other’s “individual moos.” They regularly share “cues in certain situations and express different emotions, including excitement, arousal, engagement and distress.” Other scientists are praising young researcher Ali Green, whose 333 recordings and voice analysis studies of moooosic is like “building a Google translate for cows.”

Design appears everywhere scientists look when they take their Darwin glasses off. For quality research that actually does some good for people, join the Uprising.

Photo credit: Japanese pearl oyster, Pinctada fucata, via Okinawa Institute of Science and Technology (press release).