Category: Biology

A Close Encounter with a Giant Horsefly: Insights and Discoveries | August 05 2026, 01:33

I just had a huge, about three and a half centimeters across, loud buzzing black fly come into my room. I caught it with a blanket and shoved it into a vase, inspected it closely and Googled it. It turned out to be a black horsefly (Tabanus atratus), female. The females are vampires. They need fresh blood. For the eggs. And their bites are very painful. Essentially, a horsefly’s mouth is like scissors. A pair of serrated mandibles which they use to saw into the skin, opening up capillaries, and then they lick up the blood from the resulting pool. It’s said that their bites hurt a lot because you are literally being cut by these scissors. An anticoagulant is injected into the blood to prevent it from clotting, so the wound oozes for a long time after the horsefly has flown away. They can easily bite through fabric, so a shirt offers no protection.

So, it turns out that horseflies are possibly the fastest flying insects on the planet. Males of the genus Hybomitra (which also live here) are credited with speeds up to 145 km/h, and this, by some estimates, is the record for horizontal flight among insects (though this figure is indirectly obtained: an entomologist made a male chase a bullet shot from an air rifle, it intercepted it in the air, meaning it was flying faster than the pellet). Furthermore, horseflies are attracted to polarized light. This is how they find water — a smooth surface reflects light horizontally polarized, and for the horseflies, this is a beacon “here you can lay eggs”. Interestingly, this is also why white horses get significantly fewer bites, because they almost do not polarize reflected light. For these experiments, Gabor Horvat and his colleagues received the 2016 Ig Nobel Prize. Among other things, they smeared full-size horse models with glue and painted dummies to thoroughly check everything.

By the way, I released my captive.

Grandmothers Partially Right: The Cold Truth About Catching Colds | August 02 2026, 21:03

HEY, for half a century, science condescendingly explained to grandmothers that a cold is caused by a virus, not a draft, and in 2022 found the mechanism by which the grandmothers were right after all (partly).

Background: Salisbury, 1946-1990, Common Cold Unit, 20,000 people went through it – they were infected with cold viruses and frozen (cold baths, drafts, wet swimsuits). They did not get sick more often. Next – Douglas’s work in 1968. There were 44 people, all given rhinovirus, one group sat at 4°C. No difference was found, and the article was titled “Failure to demonstrate effect”. The conclusion spread through popular books – cold has no relation to getting a cold, period.

New: In December 2022, they published the mechanism. In short. The nasal mucosa has a frontline (only discovered in 2018). Sensing a pathogen, cells throw extracellular vesicles into the nasal mucus – the authors describe this as “kicking a wasp nest”. These vesicles feature the same receptors that the virus latches onto, denser than on the cells themselves – it sticks to the dummy and doesn’t reach the cell. Then the experiment – 15 minutes at 4.4°C – and the temperature inside the nose drops by 5°C. On tissue cooled just the same, nearly 42% fewer vesicles are thrown, antiviral microRNAs in each are halved, and up to 70% fewer receptors.

Conclusion: “getting a cold from cold” is wrong, but “easier to get infected in the cold if there is someone to catch it from” is very much so. The most interesting part is what they want to make out of this. Since the swarm can be summoned, the authors discuss a spray that commands the mucosa to “kick the wasp nest” in advance.

Exploring the Odd and Ingenious with Engineer’s Zen | June 25 2026, 03:38

Just a reminder that I have the Engineering Zen group on Facebook and Telegram. Recently, these topics have been covered:

– The 1956 TV remote control that had no batteries, no electronics, and not a single LED — and it worked perfectly. How? With a small hammer.

– SQLite — a database that exists in a trillion copies literally everywhere (even on Mars). It was developed by three people, originated on a military destroyer, and instead of a Code of Conduct, the developers adhere to a 1500-year-old charter.

– Eel eggs haven’t been seen for 2000 years. Aristotle brooded over this, followed by a 19-year-old Sigmund Freud, who dissected hundreds of eels, found nothing, and frustratedly left biology.

– Obelisks — a new “form of life” discovered in 2024. Not a virus, not a cell, nothing like anything else. And it lives right in your mouth. About one in ten people have it.

– Midjourney — the very company that creates images in Discord — is suddenly building a body scanner that “is better than an MRI”. You have to be scanned underwater. No, it’s not a joke.

– Light from sound. Catch a bubble in ultrasound — and it flashes. Inside, it’s 10,000 degrees for a moment. It’s assembled on a kitchen table, and physicists are still debating exactly how it emits light.

– Why memories can’t be erased by sheer willpower — and why it’s so easy to rewrite them. It also explains why so many people want to go back to the USSR.

– Why you can’t bring water on a plane — an honest engineering breakdown.

– Cicadas that have learned prime numbers to avoid getting eaten. They emerge every 13 or 17 years — and it’s a mathematically verified survival strategy.

– A Japanese mathematician who proved a great hypothesis over 500 pages in his invented language with “Hodge theatres” and “frobenoids”. Half the world believes him, the other half found a flaw. A very beautiful and very sad story.

– And for dessert — the bigger brother of a flying manhole cover in Moscow: a cast iron plate that was launched upwards at a speed of 67 km/s by a nuclear explosion in 1957 — six times faster than escape velocity.

Join us to not miss out on a lot more interesting stuff.

Also on Telegram @engineersdzen

Exploring Ambivalence: A Review of Andy Weir’s “Project Hail Mary” | June 19 2026, 14:11

I finished reading Project Hail Mary by Andy Weir. My feelings are mixed.

On one hand, Weir is an absolute genius of hard science fiction. It’s evident that the universe is developed down to the smallest details. The author doesn’t just make up facts; the laws of physics, chemistry, biology, space navigation — everything is based on real modern scientific concepts. The problems the main character solves are logical, and following the plot development is insanely interesting. Pure delight for the inner geek.

But on the other hand… throughout the novel, I couldn’t shake the feeling that I was reading young adult or even children’s literature.

For instance… Ryland Grace, the main character, behaves not like a leading scientist stranded alone in deep space on a mission to save humanity, but like a hyperactive school teacher (which he actually was). His inner monologue is filled with childlike wonder, and instead of normal adult swearing in stressful situations, he uses amusing euphemisms. And generally, the idea that a single scientist should be able to quickly retrofit a spacecraft on the fly with a “sticks and stones” approach just to make it work is – well.. that’s something.

Too tame and kind space. All conflicts on Earth before the launch are resolved suspiciously easily thanks to the “absolute power” of project leader Eva Stratt. Her actions often look caricatured, not realistic. And when the alien Rocky appears… Their friendship develops by the canons of a classic Disney fairy tale. They instantly find a common language, they have perfect mutual understanding, zero cultural barriers, or dangerous misunderstandings. Everything is very cute, conflict-free, and “on friendship.” Adding some conflict for sharpness would have been nice. Everything always goes smoothly for the main character.

Writing style. Short, chopped sentences, very simple language, chewing over every thought, constant exclamations. The text seems specifically adapted so that a twelve-year-old could easily read it. The plot moves in circles: a problem arises => Grace in panic => Grace calculates something on paper / Rocky helps with an alloy => problem solved. And so every 30 pages. Because of this, towards the end, the sense of real danger is lost: the reader knows in advance that the author has another scientific trump card up his sleeve.

As a result, it turned out to be a cool, very scientifically accurate… comic book. A kind, optimistic fairy tale, wrapped in relatively impeccable physics and mathematics. There’s definitely a lot to praise the book for, but if you’re expecting a deep psychological drama or existential horror from fiction — this is clearly not for you.

Who read it, what did you think? Did you also catch this feeling of a “kindergarten” on a spaceship, or am I being picky?

Understanding the Surprising Subterranean Lives of Bees | June 09 2026, 01:12

I learned today that 70% of all bee species live underground. Another ~25% live in wood, and only ~5% live in hives, build combs, or live in colonies. Male bees are homeless; they’re only allowed home for sex. Outside, it’s cold, hungry, and dangerous. To protect themselves from predators, males of some species gather in “sleeping camps”. They hang onto grass blades with their jaws, stretch out their legs, and fall asleep in clusters of several dozens. They defend themselves from predators through the “dilution effect” – the more bees in a pile, the less likely you are to be eaten. The idea is simple: a predator can eat only a limited number of victims in one go. If you’re sitting on the stem alone and a predator comes – you’re eaten, the chance of dying is ~100%. But if there are fifty of you on the stem, the predator will still take one or two bees, but your chance of becoming the victim drops to a couple of percent. Red currant likely protects itself in a similar manner.

You might ask, who are the predators that eat bees? Mainly in those regions, it is the bug Apiomerus flaviventris. The bug pierces the sleeping male with its proboscis and sucks out the contents. Don’t ask where it pierces

The Intriguing Life and Science of Ilya Mechnikov | June 02 2026, 11:32

Talk about tons of weird and intriguing stuff about Ilya Mechnikov (biologist). His older brother (Ivan) – a prototype for Leo Tolstoy’s “The Death of Ivan Ilyich.” Another brother (Lev) – an anarchist, sociologist, fought in Italy alongside Garibaldi. Mechnikov himself made two attempts to depart this life: the 1st time — after the death of his 1st wife (who, suffering from tuberculosis, was carried into the church on a chair). Mechnikov swallowed morphine but survived. The 2nd time — when his 2nd wife contracted typhoid. He deliberately infected himself with relapsing fever. Both survived. By the way, this 2nd was his 15-year-old teacher (when he was 30).

Odessa. The country’s first bacteriological station on Leo Tolstoy street 🙂 An employee there botched a vaccine for anthrax and a whole flock of sheep died. Scandal => M emigrated to Paris.

Paris. Came under the wing of Louis Pasteur (the father of pasteurized milk). P supported M’s theory, gave him a lab in his institute for 28 years. M worked there for free.

M advanced the theory that not everyone who gets infected becomes sick and dies. Basically, it’s all about (of course) the gut microflora. To prove it, he deliberately drank cholera vibrios. Nothing, he got lucky (“lucky as you were”, M thought)

Not satisfied. To prove that it was about the microflora, he made his lab assistant Latapie drink cholera. Hmm, then M gave the culture to a second person, the biologist-watchman J.-B. Joupié. Joupié nearly died. Mechnikov: yay, it works: different microfloras, the microbe works differently (hmm).

Result – Nobel Prize for phagocytosis (cell immunity). And he is also the “father of gerontology”: M proposed that for longevity, one needs to quell “bad bacteria” using probiotics (hmm).

In the end, he still died after the third heart attack. In Paris, his ashes are kept in the library of the Pasteur Institute. Also, in English Wikipedia, he is Élie Metchnikoff. Hard to guess.

In the photo, Mechnikov is persuading Leo Tolstoy that he is not a charlatan.

Understanding the Tingling Sensation from a Charging Laptop | May 31 2026, 15:27

Today I learned why there’s a tingling sensation from the metallic body of, say, a MacBook when it’s charging. The effect is called electrovibration, and it arises due to parasitic capacitive coupling and the absence of grounding in the standard power supply. This seemed kind of obvious, but exactly how it works was not.

Inside the charger, there is a capacitor, which allows a safe but noticeable potential of AC current to seep into the aluminum laptop case. When you touch the cover, your body and the laptop become a sort of living capacitor, with a thin layer of aluminum and skin acting as an insulator that separates the charges.

The pulsation of current in the socket – 50-60 Hz. The electric field between the finger and the body sometimes strengthens, sometimes weakens. According to Coulomb’s Law, this causes the skin to be attracted to the metal and then released. If you simply rest your hand on the laptop, the force of this attraction is too small to notice.

It results in sensory deception – nerve endings in the finger pads, which in nature are responsible for recognizing textures, go haywire from such microscopic friction chaos. The brain is completely unable to directly recognize electrostatic microcurrents, so it chooses the most logical interpretation for itself and convinces you that it’s the metal itself that is vibrating.

The Radical Survival Strategy of Elysia marginata: Decapitation and Regrowth | May 24 2026, 21:10

Today I learned about the sea slug Elysia marginata, which (I quote) can lose its head like no other: when this slug is overwhelmed by parasites, it doesn’t go on marathons to Instagram gurus but takes a radical approach — it detaches its head and starts a new life. (I quote Anna Fe above and below because I learned everything from her post) The slug’s neck has a special groove labeled “cut here.” The head separates along this line, not immediately, but over several hours. Having shed its fatty, annoying body, the head, giggling, crawls away, saying “goodbye” to its former self – along with all the parasites, and also with the heart, kidneys, intestines, and reproductive organs. The slug survives understandably – “like everyone else, using its head (it eats with it).”

And here I started thinking: is the definition of a head—where you eat from? How do biologists understand where the head is in some fantastical creature? For example, does a sea cucumber have a head?

I Googled it. Wow, interesting. No, the head is not where you eat from. It is what first encounters the surrounding environment when moving forward. Since this end needs to quickly understand what’s ahead (danger or food), during evolution, two things concentrate there:

1) Main sensory organs (eyes, antennae, locators, chemical receptors)

2) CNS (brain or the largest nerve nodes – ganglia), to instantly process the information received from these organs.

Therefore, they write, when a biologist looks at an unknown fantastical thing,” he looks not for the mouth, but for the main control point. Where there is the highest concentration of nerve cells and receptors, there is the head.

But let’s return to the independent head of the slug. How does it manage without a stomach?

These slugs feed on algae and are able to retain their chloroplasts (structures for photosynthesis) in their tissues. Thus, the head temporarily turns into a plant and gets energy directly from sunlight, while it regrows its new body. The wound on the neck heals within 2 days, a new heart takes about a week to grow, and a fully new torso with all organs—just 20 days.

The former body, meanwhile, just lives its life on the ocean floor. Its heart beats and nerves feel, but poor thing, it cannot eat and eventually dies from exhaustion.

Near-Miss at Leningrad: The Unknown Predecessor to Chernobyl | April 26 2026, 17:32

On the anniversary of Chernobyl. Those interested in this topic may not know that a similar accident could have occurred ten years earlier on the main (very first RBMK-1000 unit) Leningrad Nuclear Power Plant.

There was a nearly identical situation: one turbine in operation, reactor shutdown by emergency protection, and subsequent power escalation.

Back then, the situation was saved by the Chief Reactor Operator Mikhail

Karrask, who, acting intuitively and relying on his experience with industrial reactors, introduced into the reactor in portions

12 manual control rods

BEFORE pressing the emergency shutdown button.

A couple of years ago, Karrask passed away. This story is almost unknown outside the industry. For proof, google his obituary on Rosatom.

The technical part. The main danger of the RBMK reactors at that time was in the design of the control rods. At the bottom, they were equipped with graphite “displacers”. When the emergency shutdown button was pressed, the rods began moving down, and in the first seconds, the graphite tips did not dampen the reactor, but on the contrary, displaced the water and increased the power in the lower part of the active zone. But precisely, the instructions in case of trouble suggested pressing the emergency shutdown button. If you followed the instructions, “Chernobyl” would have happened earlier.

After the incident at the Leningrad NPP, a commission was formed. Experts (including those from the Kurchatov Institute of Atomic Energy) pointed out the dangerous design flaws of the RBMK – the positive void coefficient of reactivity and incorrect design of the rods. Unfortunately, extensive changes to the design of all RBMK reactors were not made at that time. Only operational regulations recommendations were given, which, as history showed, were insufficient to prevent the tragedy in Chernobyl.

Crabs in Love: Monogamous Parasites of Sea Turtles | April 15 2026, 21:56

WOW, it turns out that under the shell near the anus of sea turtles, the parasitic crabs Planes minutus make themselves at home, and there’s only enough space for a cozy duo, so they form a monogamous pair and live happily ever after inside the turtle’s butt (had no idea what to do with this information, so I brought it here). In relation to the turtle, this is commensalism. It’s when it’s good for one (or in our case, two), and the third doesn’t give a damn. I see a scientific paper claiming that they sometimes mistake the turtle for ocean debris, where there’s room for more than one wife, and then, goodbye monogamy. But, at least, no butts involved.