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I give Yuka a choice of three treats. He chooses the one on the right, then halfway through stops, goes to sniff the other two just in case, one by one, but ultimately sticks with his original choice and leaves with the treat in his mouth. At the staircase, he decides to return anyway, checks that the other two are still there, sniffs them again one by one, weighs the options, realizes that no, the one he chose is indeed tastier, and leaves.

After some time, having chewed on what he deemed the tastiest, he returns and is surprised to find that the other two are gone. And he’s still scratching at the pantry door. Such injustice! There were three! on the floor!

I wonder which Community Standard I am violating with this comment?

The CIA just dumped some warez here. Swarm it, there’s 150 episodes of Tom and Jerry on the Al-Qaeda leader’s laptop, no SMS and no registration, plus various other bits and pieces. Link in the comments.

Continuing to read Immense World by Ed Yong. I ordered his previous book, “I Contain Multitudes,” about the microbiota. But that’s for later. Currently, there’s an intriguing story unfolding from the pages as I read.

In previous posts, I mentioned that Catfish — those whiskered little fish — have taste receptors all over their bodies, from head to tail, numbering between 100,000 to 150,000. For comparison, humans have about 9,000, and chickens — 24. Thus, their life at the bottom in murky and muddy water is made easier as they can taste the water with their entire body.

I am now reading that in 2012, Daphne Soares, a biologist from the nearby University of Maryland, discovered something interesting about the Astroblepus Pholeter catfish from a cave in Ecuador. She found that these blind catfish evolved in the turbulent currents of the cave in such a way that their skin became covered with what she called “micro-joysticks,” but the interesting part is not just that, but that these “micro-joysticks” are essentially teeth. They don’t look like teeth, but they are indeed made from enamel and dentin, with nerves connecting to all of this. These tooth-like formations on the skin are called denticles.

There are other fish with denticles, but usually, they use them as a “tool” for “cutting,” as well as for protection, or for reducing resistance while swimming. However, cave catfish use these denticles as mechanosensors for navigation in dark and fast-flowing environments, needing more robust sensors, much like how other fish use the lateral line.

Incidentally, on Daphne Soares’ personal website, among the list of discoveries is also the previously unknown sensory organ in alligators — integumentary sensory organs (ISOs). They appear as black dots of about half a millimeter on the alligator’s face. With them, crocodilians feel water disturbances and changes in pressure (which are essentially the same thing). And they are very sensitive — able to detect water movements as small as 4 micrometers, which is less than the thickness of a human hair.

It also turns out that male alligators can produce very low sounds, which are detected by the female with these sensitive cells on the snout. It is unknown what the female then does with this information, but at least she’s now informed. Unknown what you will do with all this information, but at least you are now informed as well.

Eggplants

I stumbled upon a very interesting channel for engineers on YouTube called Lesics. It has a lot of fascinating content. Start, for instance, with a 15-minute video about the engineering details of constructing the Golden Gate Bridge. It was built in 1937 under the supervision of Joseph Strauss. You will quickly realize that the projects you are working on are trivial and insignificant compared to the challenges faced in the early 20th century. Constructing a bridge weighing nearly a million tons in a way that it could withstand load challenges unimaginable at that time is comparable to building spacecraft today. I’ve attached the link to the video in the comments.

I continue reading Ed Yong’s book Immense World about how animals interpret signals from the surrounding world. Very interesting stuff about seals.

What I learned. Seals are known for their ability to use their extremely sensitive whiskers to precisely follow the hydrodynamic trail left by their prey. To us, it looks like this: a fish swims through a complex curve, then a minute later a seal appears and follows the same curve (although a straight line might have been shorter to the fish). Research has shown that a seal can track a swimming herring from up to 180 meters away — which is comparable to dolphins’ echolocation system.

How do they manage this?

In one experiment, a complex curve was “drawn” in the water along a pool, and then seals were released, and they moved along this curve, although to our eyes, and indeed anyone’s, there was nothing left of it. This is despite the fact that the ocean water is constantly moving. The swimming fish leaves what is called a hydrodynamic trail – water vortices that last for some time (minutes), and the seals’ whiskers detect them.

It should be mentioned that seals have so-so vision, plus the water is significantly opaque (when we talk about a hundred meters) in their habitats, plus this experiment was also conducted with the vision of the seals being blocked (I don’t know how to translate blindfolded better). Vision is generally mediocre both underwater and above water for almost everyone. Birds, then humans, various felines, and a few others are exceptions.

But vortex flows are also created by the whiskers themselves — how do seals distinguish those created by the fish? It turns out that seal whiskers have a wavy structure, thickening and thinning in certain areas, which helps suppress the excitement caused by the vortex flows of the seal itself and the whiskers, and against this background, enhance the vortex flows from fish that swam in that place earlier. Ultimately, this feature increases the sensitivity of the whiskers to the hydrodynamic trails left by prey, allowing seals to hunt effectively even in conditions of poor visibility. And this is unique to seals. For instance, walruses and sea lions have simpler whiskers, and they are not as good at tracking hydrodynamic trails.

By the way, there is something similar in all fish — an organ called the lateral line. It looks like a thin line on both sides of the body, stretching from the gill slits to the base of the tail. When you are cutting up a fish, take notice, it’s quite noticeable in many of them. Lateral line organs help fish navigate, sense the direction and speed of currents, as well as detect prey or enemies, and of course, to swim synchronously in a school without bumping into each other. The sensitivity there is far from the aforementioned in seals, of course, but it is claimed that some fish can thus detect the disturbance from an insect on the surface.

Also interesting, catfish have a unique ability to perceive taste with their entire body – they essentially have taste buds located all over their surfaces from head to tail.

By the way, if a fish in an aquarium is looking at you, it appears as “fish sideways” and not “fish nose at me”. Most likely, a typical fish sees almost nothing directly in front of itself, and the area of maximum clarity is to the left or right side. So if you imagine that it is examining you, then stand by its side.

Well, I hope this was interesting. I don’t understand how some can read, I quote, “600 books a year”. When do they think? When do they stop and google? Sigh.

Should I craft a little house for him… Meanwhile, the cat is posing

The day started with Yuka waking me up with his paw and clearly showing that we need to go downstairs. We go down, he rushes to the window, and outside — snow, everything is white. Look, master — it’s winter! He barely let me have breakfast, insisted on going for a walk.

After a walk, I let him out into the yard to run around. He behaves kind of like in this video, only outdoors. Somehow, I go out and see the gate is open (unclear why – the latch is torn off, but it was always “hanging by a thread”, and it’s on the outside of the gate, not inside). And Yuki is gone. I rush to put on my sneakers, open the door on the other side of the house — he runs back home by himself. Very strange. Usually, he would just bolt toward the horizon, but apparently, his training has overcome him this time, and squirrels or other dogs were not in sight.

In short, he came home, and he’s still in the mood like in the video 🙂 When he really wants to play, we have our own language that somehow works for him, so I’m there growling in the background. Generally, he sometimes goes wild (quite rarely though).

I continue to read Ed Yong’s book “An Immense World”.

He writes about the emerald jewel wasp. This wasp—a beautiful creature about an inch long with a metallic green body and orange thighs—is a parasite that raises its young on cockroaches. When the female Ampulex compressa finds a cockroach (which is twice her size), she stings it twice: first in the middle of the body to temporarily paralyze its legs, and a second time in the brain. The second sting targets two specific groups of neurons and delivers a venom that deprives the cockroach of the desire to move on its own, turning it into an obedient zombie. In such a state, the wasp can lead the cockroach to its lair by the antennae, much like a person leads a dog. There, she lays an egg on it, providing her future larva with a compliant source of fresh meat.

This act of mind control depends on the second “sting,” which the wasp must deliver precisely to the right spot in the brain. There’s almost no brain there, and what is there is hidden somewhere among a tangle of muscles and internal organs. How does she manage?

Fortunately for the wasp, its stinger is not only a drill, venom injector, and egg-laying tube, but also a sensory organ. Its tip is covered with small bumps and indentations, sensitive to both smell and touch. With their help, she can detect the cockroach’s brain. When Gal and Libersat removed a cockroach’s brain before offering it to the wasp, she tried to find the organ, but in vain. If the brain was replaced with something of the same consistency, then the wasp found the brain, but then got confused. Thus, it can distinguish the brain from everything else with its “nose.”

Another interesting story is about the red knots, shorebirds. There are many such birds on the ocean, they probe the sand along the shore with their beaks in search of buried treasures—worms, mollusks, and crustaceans. Under the microscope, the tips of their beaks are pitted like corncobs from which all the kernels have been eaten. These pits are filled with mechanoreceptors, similar to those on our skin, particularly on our palms and fingers, and allow the birds to detect buried prey by touch.

But how does a shorebird know where to insert its beak first? Underground prey is not visible from the surface, so one might assume that the birds simply dig randomly and hope for the best.

However, in 1995, Dutch scientist Theunis Piersma showed that the birds find mollusks eight times more often than one would expect if they were searching randomly. They must have some technique. To figure it out, Piersma trained birds to inspect buckets filled with sand for buried objects and report if they found anything by approaching a specially equipped feeder. This simple experiment showed that the birds could detect mollusks buried even deeper than they can reach with their beaks. During the process, it turned out they were able to sense stones, so they clearly did not rely on smells, sounds, tastes, vibrations, heat, or electric fields.

Piersma suggested that these birds use a special form of touch that works at a distance. When a red knot’s beak plunges into wet sand, it “pushes” fine jets of water between the grains, creating a wave of pressure that radiates outward from that spot. If there is any solid object in the path (like a mollusk or a stone), the water has to flow around it, distorting the pressure pattern. The pits at the beak tip of the knot are tuned to sense these distortions. Moreover, the bird “collects” data from its radar from different points, allowing it to make fewer attempts than if it acted by unscientific probing.

It’s clear that this is a hypothesis, but one backed by experiments making it quite plausible. Because nothing else can explain the observations.

Ed also writes something interesting about the touch sensation in star-nosed moles. These are eyeless animals with a large red star on their nose. This star-shaped growth is the most sensitive tactile system known to contemporary science. Biologists have counted more than 100,000 nerve fibers in it: this is five times more than in a human hand, which is also considered to have very high sensitivity. And these 100,000 are packed into their organ, smaller than a fingertip. The sensory receptors are known as “Eimer’s organs,” named after the scientist who first observed them. They help the mole detect seismic vibrations from the environment.

Thanks to the vast number of sensory receptors, the star-nosed mole is able to find an object, determine whether it’s edible or not, and then eat it (if it’s an insect or worm) in less than 120-150 ms. That’s about the time it takes for us to blink. In this time, by merely touching what can be a worm, they understand it’s edible, and manage to “chew” it before we finish blinking. As a result, the star-nosed mole can touch and check up to 13 different small objects per second. Data exchange occurs fantastically quickly: the brain makes a decision in 8 milliseconds, which is the theoretical speed limit of neurons.

The sense of smell is also unusual. It is usually believed that mammals cannot smell underwater. Well, this creature can. To do this, moles use a unique technology. Chasing prey in swampy areas, they blow bubbles into the water, then inhale them back through their nostrils. Meanwhile, the direction of their movement correlates with the movement of the prey.