November 4, 2022 | David F. Coppedge

Animal Magic: Awesome Adaptations by Design

From elephant fingers to ants’ feet, nature is filled
with wonders of engineering.

 

“Feet” of Engineering

A study of polar bear paw papillae shows how they maintain traction on ice (Phys.org, 2 Nov 2022). Look at the photo of the bottom of a bear’s paw in this article by Bob Yirka. Those tiny microstructures on their foot pads, called papillae, are what enable them to walk on ice without slipping. He tells how researchers at the University of Akron in Ohio figured this out.

Suspecting that taller papillae served a specific purpose, the researchers created 3D models of the polar bear paw pad that showed that taller papillae result in better traction—an important characteristic for a bear that walks on ice most of the time. More specifically, they found that the papillae were 1.5 times taller than those of brown or black bears. They also found that the taller papillae meant that polar bears had 1.3 times more paw surface area, giving the polar bear paws a 30–50% increase in frictional shear stress.

How do ants crawl on walls? A biologist explains their sticky, spiky, gravity-defying grip (The Conversation, 12 September 2022). Have you ever wondered how ants can climb walls and even walk on ceilings with ease? Look at the electron micrographs of an ant’s foot provided by biologist Deby Cassill from the University of South Florida, and read her description of how the hooks, spines, and hairs get a grip on surfaces rough and smooth. Gravity actually helps them grip the wall. Especially intriguing are the reversible glue pads at the tips of the feet:

When an ant walks up a wall or across a ceiling, gravity causes its claws to swing wide and pull back. At the same time, its leg muscles pump fluids into the pads at the end of its feet, causing them to inflate. This body fluid is called hemolymph, which is a sticky fluid similar to your blood that circulates throughout an ant’s body.

After the hemolymph pumps up the pad, some of it leaks outside the pad, which is how ants can stick to a wall or a ceiling. But when an ant picks up its foot, its leg muscles contract and suck most of the fluid back into the pad and then back up the leg. This way an ant’s blood is reused over and over – pumped from the leg into the pad, then sucked back up the leg – so none is left behind.

Credit: Illustra Media and Captain Dave’s Whale and Dolphin Safari

Hardy Animals Big and Small

Why whales don’t get brain damage when they swim (University of British Columbia, 22 Sept 2022). It takes a lot of work to move a whale’s gigantic tail fluke. Muscular effort can damage brains in mammals by sending pulses of high pressure through capillaries. Horses breathe to prevent those pulses, but what about whales that have to hold their breath while swimming? This Darwin-free press release reports how a team of UBC researchers led by Margo Lillie figured this out. Whales have networks of blood vessels called retia mirabilia (“miraculous nets”) surrounding their brains.

Dr. Lillie and colleagues theorized that the retia use a ‘pulse-transfer’ mechanism to ensure there is no difference in blood pressure in the cetacean’s brain during movement, on top of the average difference. Essentially, rather than dampening the pulses that occur in the blood, the retia transfer the pulse in the arterial blood entering the brain to the venous blood exiting, keeping the same ‘amplitude’ or strength of pulse, and so, avoiding any difference in pressure in the brain itself.

Illustra Media’s film Living Waters shows another function of retia mirabilia in whales. The network of arteries and veins transfers heat away from the male’s testicles so that excess heat, which would damage sperm production, can be carried off through veins to the tail fluke and flippers and then shed out of the body into the ocean environment.

UW Researchers Advance Knowledge of Microscopic Creature’s Durability (University of Wyoming, 17 Oct 2022). The cute little “water bears” are arthropods called tardigrades, just a half a millimeter or so in length, live almost everywhere. They can survive almost anything. Scientists have long been curious how they survive extreme heat, extreme cold, dessication, radiation and other conditions that would kill most animals. Researchers found that they have a sweet trick to some of their survival tactics, using a sugar called trehalose.

The tardigrade, a water-dwelling micro-creature that measures less than half a millimeter long. From Wikimedia Commons.

Tardigrades’ ability to survive being dried out has puzzled scientists, as they do so in a manner that appears to differ from a number of other organisms with the ability to enter suspended animation. At one time, scientists thought tardigrades did not manufacture trehalose to survive drying up, but [Thomas] Boothby and his team found that they do produce the sugar — just at lower levels than other organisms.

The researchers also found that, in tardigrades, trehalose works synergistically with another tardigrade-specific protein called CAHS D.

Incidentally, trehalose has been studied for possible use to dehydrate and preserve blood at ambient temperatures for transfusions in remote areas such as on battlefields (4 March 2004).

Turtle Talk and Other Surprises

Elephant facial motor control (Kaufmann et al., Science Advances, 26 Oct 2022). Did you know that African elephants have fingers at the end of their trunks? Two “trunk tip fingers” allow them to grasp and pinch objects with fine motor control. Well, that implies some impressive hardware and software must exist from tip to brain.

German scientists found impressive facial muscles in African elephants, more than those of Asian elephants which tend to roll objects with their trunks. Both species have more facial neurons than other land mammals. In elephants, those neurons have a long way to go down the trunk.

Elephants at a zoo. (DFC)

Facial nucleus neurons (~54,000 in Asian elephants, ~63,000 in African elephants) outnumbered those of other land-living mammals. The large-eared African elephants had more medial facial subnucleus neurons than Asian elephants, reflecting a numerically more extensive ear-motor control. Elephant dorsal and lateral facial subnuclei were unusual in elongation, neuron numerosity, and a proximal-to-distal neuron size increase. We suggest that this subnucleus organization is related to trunk representation, with the huge distal neurons innervating the trunk tip with long axons. African elephants pinch objects with two trunk tip fingers, whereas Asian elephants grasp/wrap objects with larger parts of their trunk. Finger “motor foveae” and a positional bias of neurons toward the trunk tip representation in African elephant facial nuclei reflect their motor strategy. Thus, elephant brains reveal neural adaptations to facial morphology, body size, and dexterity.

Vocal communication recorded in 53 animals we thought were silent (New Scientist, 25 October 2022). Christa Lesté-Lasserre starts her article with a cute photo of a painted wood turtle, then tells how Gabriel Jorgewich-Cohen discovered vocal communication in turtles and other reptiles, like the tuatara.

The 53 species the team studied had a varying range of acoustic capabilities, from chirps and clicks to more advanced, complex sounds of different tones. Many researchers agree that when animals use their respiratory tracts to create complex repertoires of different sounds or harmonic calls, they are communicating with each other, says Jorgewich-Cohen.

He also filmed with underwater cameras while recording sound to investigate what behaviours might be linked to the noises. The most obvious forms of communication were produced by males while courting females or during conflicts with other males.

Chuck in the Box makes another unsolicited appearance.

Both reporter Lesté-Lasserre and scientist Jorgewich-Cohen with their double-jointed surnames drag Darwin into the picture, stating that vocal communication must have started many millionnnnssssszzzz of yearssszzzz ago. But to allege it, they have to raise the perhapsimaybecouldness index past the red line:

Rather than evolving in many animals independently, the research suggests that vocal communication arose in a common ancestor more than 400 million years ago….

In fact, vocal communication might be even more ancient than that, says Jorgewich-Cohen. Lungless fish produce vocal sounds as well, and it is possible that they evolved this trait and then passed it on to later generations that developed lungs. “It could be that one lineage of those fishes was the precursor of the type of sound that we make as [choanates],” he says. “So it could be actually that this lineage of sound production is older than what I found.”

The lead scientist was surprised that no one had discovered turtle vocalizations before. His research, including evolutionary notions, was published in Nature Communications on 25 Oct 2022 (open access) with the title, “Common evolutionary origin of acoustic communication in choanate vertebrates.” (Choanates is a term encompassing lungfishes and tetrapods.)

Just give us the facts without the Darwin commercial and we’ll be happy.

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