What are hacks for remembering biology

Camouflage coats and stone eyesBiologists decipher nature's tricks

At first glance, beetle snails are most likely to be reminiscent of woodlice without eyes or legs. Because these sea creatures do not have a classic snail shell, rather they hide their soft bodies under a series of individual armor plates. They offer protection, but have the disadvantage that you cannot see through them. However, the beetle snails have found a way out of this problem: Hundreds of microscopic lens eyes are incorporated into their shell:

"This whole armor, like the lenses, is made of calcium carbonate. So these eyes are very different from ours: They are not made of organic substances, but basically of stone."

One and the same material in the body armor protects the animal and allows it to perceive its environment, explains Ling Li from Harvard University in Boston. The researchers found out how this works with CT scans of the tank:

"As almost always with such multifunctional systems, this combination also has disadvantages. The larger the individual lenses and the more eyes the animals have, the easier it is for the animal to cling to the rock for self-defense. In return, however, the mechanical stability of the shell suffers . "

Because the crystals in the lens eyes are larger and arranged in such a way that they bundle incident light: This structure, however, makes them weaker than the rest of the armor. How the animals balance the advantages and disadvantages in order to optimize this dual function makes the beetle snails interesting for materials scientists:

"By examining the beetle snails, we can learn how the animals control the structure of their shell locally and find an optimum between their sensory abilities and the protective function to produce built-in sensors that monitor their own structural integrity. "

Solution strategies for technical problems can often be found in nature. This is why basic biological research always gives rise to interesting approaches. Another example of this is the question of how fish protect themselves from predators in the open sea. Because there are no hiding places there. The solution is - in the truest sense of the word - in the eye of the beholder, explains Molly Cummings from the University of Texas at Austin:

"The open sea appears to us as uniformly blue. But water polarizes light, so it gives it certain directions of oscillation. If we could perceive polarized light, the sea would look like a kaleidoscope with countless colors, which - depending on the degree of polarization - are sometimes brighter and sometimes paler. "

However, this is wrong with the classic assumption that fish camouflage themselves in open water by reflecting light with their silvery bodies like mirrors. That doesn't work in polarized light. The reason: Due to the reflection in the mirror, the angle of the polarized light changes - and your own silhouette would be perfectly reflected in the surroundings, says Parish Brady from the University of Austin:

"We therefore carried out a series of experiments, first in the laboratory and later in the sea, on species of jacks that live in open water and reef-dwelling species."

The result: The species from the open sea merge much better with their environment in polarized light than their relatives, who can hide in the reef. The reason for this lies in the fish skin:

"The jacks from the open water have specialized platelets in their skin. They are microscopic and are structured and arranged in such a way that they do not simply reflect polarized light. Rather, they adapt the reflection in polarization direction and intensity to the ambient light."

There are also practical applications for this camouflage strategy in polarized underwater light:

"Not only can fish see polarized light, but also satellites with polarization cameras on board that are supposed to track down targets in the ocean. Whoever wants to prevent this - and we know which people want that - could imitate the technology of these fish."