Biology

getting-to-the-bottom-of-how-red-flour-beetles-absorb-water-through-their-butts

Getting to the bottom of how red flour beetles absorb water through their butts

12 days of Christmas, agricultural sciences, animals, beetles, Biology, Biomechanics, genomes, Genomics, red flour beetle, Science / /

On the third day of Christmas —

A unique group of cells pumps water into the kidneys to help harvest moisture from the air.

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Who <em>doesn’t</em> thrill to the sight of a microscopic cross-section of a beetle’s rectum? You’re welcome.” src=”https://cdn.arstechnica.net/wp-content/uploads/2023/03/beetle-butt-TOP-800×536.jpg”></img><figcaption> <p><a data-height=Enlarge / Who doesn’t thrill to the sight of a microscopic cross-section of a beetle’s rectum? You’re welcome.

Kenneth Veland Halberg

There’s rarely time to write about every cool science-y story that comes our way. So this year, we’re once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2023, each day from December 25 through January 5. Today: red flour beetles can use their butts to suck water from the air, helping them survive in extremely dry environments. Scientists are honing in on the molecular mechanisms behind this unique ability.

The humble red flour beetle (Tribolium castaneum) is a common pantry pest feeding on stored grains, flour, cereals, pasta, biscuits, beans, and nuts. It’s a remarkably hardy creature, capable of surviving in harsh arid environments due to its unique ability to extract fluid not just from grains and other food sources, but also from the air. It does this by opening its rectum when the humidity of the atmosphere is relatively high, absorbing moisture through that opening and converting it into fluid that is then used to hydrate the rest of the body.

Scientists have known about this ability for more than a century, but biologists are finally starting to get to the bottom (ahem) of the underlying molecular mechanisms, according to a March paper published in the Proceedings of the National Academies of Science. This will inform future research on how to interrupt this hydration process to better keep red flour beetle populations in check, since they are highly resistant to pesticides. They can also withstand even higher levels of radiation than the cockroach.

There are about 400,000 known species of beetle roaming the planet although scientists believe there could be well over a million. Each year, as much as 20 percent of the world’s grain stores are contaminated by red flour beetles, grain weevils, Colorado potato beetles, and confused flour beetles, particularly in developing countries. Red flour beetles in particular are a popular model organism for scientific research on development and functional genomics. The entire genome was sequenced in 2008, and the beetle shares between 10,000 and 15,000 genes with the fruit fly (Drosophila), another workhorse of genetics research. But the beetle’s development cycle more closely resembles that of other insects by comparison.

Food security in developing nations is particularly affected by animal species like the red flour beetle which has specialized in surviving in extremely dry environments, granaries included, for thousands of years.

Enlarge / Food security in developing nations is particularly affected by animal species like the red flour beetle which has specialized in surviving in extremely dry environments, granaries included, for thousands of years.

Kenneth Halberg

The rectums of most mammals and insects absorb any remaining nutrients and water from the body’s waste products prior to defecation. But the red flour beetle’s rectum is a model of ultra-efficiency in that regard. The beetle can generate extremely high salt concentrations in its kidneys, enabling it to extract all the water from its own feces and recycle that moisture back into its body.

“A beetle can go through an entire life cycle without drinking liquid water,” said co-author Kenneth Veland Halberg, a biologist at the University of Copenhagen. “This is because of their modified rectum and closely applied kidneys, which together make a multi-organ system that is highly specialized in extracting water from the food that they eat and from the air around them. In fact, it happens so effectively that the stool samples we have examined were completely dry and without any trace of water.” The entire rectal structure is encased in a perinephric membrane.

Halberg et al. took took scanning electron microscopy images of the beetle’s rectal structure. They also took tissue samples and extracted RNA from lab-grown red flour beetles, then used a new resource called BeetleAtlas for their gene expression analysis, hunting for any relevant genes.

One particular gene was expressed sixty times more in the rectum than any other. Halberg and his team eventually honed in a group of secondary cells between the beetle’s kidneys and circulatory system called leptophragmata. This finding supports prior studies that suggested these cells might be relevant since they are the only cells that interrupt the perinephric membrane, thereby enabling critical transport of potassium chloride. Translation: the cells pump salts into the kidneys to better harvest moisture from its feces or from the air.

Model of the beetle's inside and how it extracts water from the air.

Enlarge / Model of the beetle’s inside and how it extracts water from the air.

Kenneth Halberg

The next step is to build on these new insights to figure out how to interrupt the beetle’s unique hydration process at the molecular level, perhaps by designing molecules that can do so. Those molecules could then be incorporated into more eco-friendly pesticides that target the red flour beetle and similar pests while not harming more beneficial insects like bees.

“Now we understand exactly which genes, cells and molecules are at play in the beetle when it absorbs water in its rectum. This means that we suddenly have a grip on how to disrupt these very efficient processes by, for example, developing insecticides that target this function and in doing so, kill the beetle,” said Halberg. “There is twenty times as much insect biomass on Earth than that of humans. They play key roles in most food webs and have a huge impact on virtually all ecosystems and on human health. So, we need to understand them better.”

DOI: PNAS, 2023. 10.1073/pnas.2217084120  (About DOIs).

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Corvids seem to handle temporary memories the way we do

animal behavior, Biology, neurobiology, Science, working memory / /

Working on memory —

Birds show evidence that they lump temporary memories into categories.

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A black bird with yellow eyes against a blue sky.

Enlarge / A jackdaw tries to remember what color it was thinking of.

Humans tend to think that we are the most intelligent life-forms on Earth, and that we’re largely followed by our close relatives such as chimps and gorillas. But there are some areas of cognition in which homo sapiens and other primates are not unmatched. What other animal’s brain could possibly operate at a human’s level, at least when it comes to one function? Birds—again.

This is far from the first time that bird species such as corvids and parrots have shown that they can think like us in certain ways. Jackdaws are clever corvids that belong to the same family as crows and ravens. After putting a pair of them to the test, an international team of researchers saw that the birds’ working memory operates the same way as that of humans and higher primates. All of these species use what’s termed “attractor dynamics,” where they organize information into specific categories.

Unfortunately for them, that means they also make the same mistakes we do. “Jackdaws (Corvus monedula) have similar behavioral biases as humans; memories are less precise and more biased as memory demands increase,” the researchers said in a study recently published in Communications Biology.

Remembering not to forget

Working memory is where we hang on to items for a brief period of time—like a postal code looked up in one browser tab and typed into a second. It can hold everything from numbers and words to images and concepts. But these memories deteriorate quickly, and the capacity is limited—the more things we try to remember, the less likely the brain is going to remember them all correctly.

Attractor dynamics give the brain an assist with working memory by taking sensory input, such as color, and categorizing it. The highly specific red shade “Fire Lily” might fade from working memory quickly, and fewer specifics will stick around as time passes, yet it will still be remembered as “red.” You lose specifics first, but hang on to the general idea longer.

Aside from time, the other thing that kills working memory is distractions. Less noise—meaning distracting factors inside and outside the brain—will make it easier to distinguish Fire Lily among the other reds. If a hypothetical customer was browsing paint swatches for Sandstone (a taupe) and London Fog (a gray) in addition to Fire Lily, remembering each color accurately would become even more difficult because of the increased demands on working memory.

Bias can also blur working memory and cause the brain to remember some red hues more accurately than others, especially if the brain compartmentalizes them all under “red.” This can happen when a particular customer has a certain idea of the color red that leans warmer or cooler than Fire Lily. If they view red as leaning slightly warmer than Fire Lily, they might believe a different, warmer red is Fire Lily.

In living color

To find out if corvids process stimuli using short-term memory with attractor dynamics, the researchers subjected two jackdaws to a variety of tests that involved remembering colors. Each bird had to peck on a white button to begin the test. They were then shown a color—the target color—before being shown a chart of 64 colors. The jackdaws had to look at that chart and peck the color they had previously been shown. A correct answer would get them their favorite treat, while responses that were close but not completely accurate would get them other treats.

While the birds performed well with just one color, their accuracy went down as the researchers challenged them to remember more target colors from the chart at once. They were more likely to pick colors that were close to, but not exactly, the target colors they had been shown—likely because there was a greater load on their short-term memory.

This is what we’d see if a customer had to remember not only Fire Lily, but Sandstone and London Fog. The only difference is that we humans would be able to read the color names, and the jackdaws only found out they were wrong when they didn’t get their favorite treat.

“Despite vastly different visual systems and brain organizations, corvids and primates show similar attractor dynamics, which can mitigate noise in visual working memory representations,” the researchers said in the same study.

How and why birds evolved attractor dynamics still needs to be understood. Because avian eyesight differs from human eyesight, there could have been differences in color perception that the research team was unable to account for. However, it seems that the same mechanisms for working memory that evolved in humans and other primates also evolved separately in corvids. “Birdbrain” should be taken as a compliment.

Communications Biology, 2023. DOI:  10.1038/s42003-023-05442-5

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study:-“smarter”-dogs-think-more-like-humans-to-overcome-their-biases

Study: “Smarter” dogs think more like humans to overcome their biases

animal behavior, animal cognition, animals, Biology, Dogs, Science, spatial bias / /

who’s a smart doggo? —

Both the shape of a dog’s head and cognitive ability determine degree of spatial bias.

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dog in a harness approaching a blue dish on the floor

Enlarge / Look at this very good boy taking a test to determine the origin of his spatial bias for a study on how dogs think.

Eniko Kubinyi

Research has shown that if you point at an object, a dog will interpret the gesture as a directional cue, unlike a human toddler, who will more likely focus on the object itself. It’s called spatial bias, and a recent paper published in the journal Ethology offers potential explanations for why dogs interpret the gesture the way that they do. According to researchers at Eötvös Loránd University in Hungary, the phenomenon arises from a combination of how dogs see (visual acuity) and how they think, with “smarter” dog breeds prioritizing an object’s appearance as much as its location. This suggests the smarter dogs’ information processing is more similar to humans.

The authors wanted to investigate whether spatial bias in dogs is sensory or cognitive, or a combination of the two. “Very early on, children interpret the gesture as pointing to the object, while dogs take the pointing as a directional cue,” said co-author Ivaylo Iotchev. “In other words, regardless of the intention of the person giving the cue, the meaning for children and dogs is different. This phenomenon has previously been observed in dogs using a variety of behavioral tests, ranging from simple associative learning to imitation, but it had never been studied per se.”

Their experimental sample consisted of dogs used in a previous 2018 study plus dogs participating specifically in the new study, for a total of 82 dogs. The dominant breeds were border collies (19), vizslas (17), and whippets (6). Each animal was brought into a small empty room with their owner and one of the experimenters present. The experimenter stood 3 meters away from the dog and owner. There was a training period using different plastic plates to teach the dogs to associate either the presence or absence of an object, or its spatial location, with the presence or absence of food. Then they tested the dogs on a series of tasks.

An object feature conditioning test involving a white round plate and a black square plate.

Enlarge / An object feature conditioning test involving a white round plate and a black square plate.

I.B. Iotchev et al., 2023

For instance, one task required dogs to participate in a maximum of 50 trials to teach them to learn a location of a treat that was always either on the left or right plate. For another task, the experimenter placed a white round plate and a black square plate in the middle of the room. The dogs were exposed to each semi-randomly but only received food in one type of plate. Learning was determined by how quickly each dog ran to the correct plate.

Once the dogs learned those first two tasks, they were given another more complicated task in which either the direction or the object was reversed: if the treat had previously been placed on the right, now it would be found on the left, and if it had previously been placed on a white round plate, it would now be found on the black square one. The researchers found that dogs learned faster when they had to choose the direction, i.e., whether the treat was located on the left or the right. It was harder for the dogs to learn whether a treat would be found on a black square plate or a white round plate.

The shorter a dog's head, the higher the

Enlarge / The shorter a dog’s head, the higher the “cephalic index” (CI).

I.B. Iotchev et al., 2023

Next the team needed to determine differences between the visual and cognitive abilities of the dogs in order to learn whether the spatial bias was sensory or cognitively based, or both. Selective breeding of dogs has produced breeds with different visual capacities, so another aspect of the study involved measuring the length of a dog’s head, which prior research has shown is correlated with visual acuity. The metric used to measure canine heads is known as the “cephalic index” (CI), defined as the ratio of the head’s maximum width multiplied by 100, then divided by the head’s maximum length.

The shorter a dog’s head, the more similar their visual acuity is to human vision. That’s because there is a higher concentration of retinal ganglion cells in the center of their field of vision, making vision sharper and giving such dogs binocular depth vision. The testing showed dogs with better visual acuity, and who also scored higher on the series of cognitive tests, also exhibited less spatial bias. This suggests that canine spatial bias is not simply a sensory matter but is also influenced by how they think. “Smarter” dogs have less spatial bias.

As always, there are a few caveats. Most notably, the authors acknowledge that their sample consisted exclusively of dogs from Hungary kept as pets, and thus their results might not generalize to stray dogs, for example, or dogs from other geographical regions and cultures. Still, “we tested their memory, attention skills, and perseverance,” said co-author Eniko Kubinyi. “We found that dogs with better cognitive performance in the more difficult spatial bias task linked information to objects as easily as to places. We also see that as children develop, spatial bias decreases with increasing intelligence.”

DOI: Ethology, 2023. 10.1111/eth.13423  (About DOIs).

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contact-tracing-software-could-accurately-gauge-covid-19-risk

Contact-tracing software could accurately gauge COVID-19 risk

Biology, COVID-19, epidemiology, infectious diseases, SARS-CoV-2, Science / /

As it turns out, epidemiology works —

Time spent with infected individuals is a key determinant of risk.

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A woman wearing a face mask and checking her phone.

It’s summer 2021. You rent a house in the countryside with a bunch of friends for someone’s birthday. The weather’s gorgeous that weekend, so mostly you’re all outside—pool, firepit, hammock, etc.—but you do all sleep in the same house. And then on Tuesday, you get an alert on your phone that you’ve been exposed to SARS-CoV-2, the virus that causes COVID-19. How likely are you to now have it?

To answer that question, a group of statisticians, data scientists, computer scientists, and epidemiologists in the UK analyzed 7 million people who were notified that they were exposed to COVID-19 by the NHS COVID-19 app in England and Wales between April 2021 and February 2022. They wanted to know if—and how—these app notifications correlated to actual disease transmission. Analyses like this can help ensure that an app designed for the next pathogen could retain efficacy while minimizing social and economic burdens. And it can tell us more about the dynamics of SARS-CoV-2 transmission.

Over 20 million quarantine requests

The NHS COVID-19 app was active on 13 to 18 million smartphones per day in 2021. It used Bluetooth signals to estimate the proximity between those smartphones while maintaining privacy and then alerted people who spent 15 minutes or more at a distance of 2 meters or less from a confirmed case. This led to over 20 million such alerts, each of which came with a request to quarantine—quite a burden.

The researchers found that the app did, in fact, accurately translate the duration and proximity of a COVID-19 exposure to a relevant epidemiological risk score. The app assessed a contact’s risk by multiplying the length of contact, the proximity of contact, and the infectiousness of the index case as determined by how long it had been since the index case started showing symptoms or tested positive.

There was an increasing probability of reported infection as the app’s risk score increased: more contacts whom the app deemed were at a high transmission risk did go on to test positive for COVID-19 within the following two weeks than those who were notified but had lower risk levels. (That’s positive tests that were reported by using the app. Some of the high-risk people probably did not test at all, did not report their test results, or did not report them within the allotted time. So this is an underestimation of the correlation between notification of risk and infection.)

More exposure = higher risk

When the researchers separated the factors contributing to the risk of an exposure, they found that duration was the most important indicator. Household exposures accounted for 6 percent of all contacts but 41 percent of transmissions.

One caveat: The app didn’t record any contextual variables that are known to impact transmission risk, like if people live in an urban or rural area, was the meeting indoors or outdoors, was it during the week or over the weekend, was anyone vaccinated, etc. Including such data could make risk assessment more accurate.

Based on their work, the researchers suggest that an “Amber Alert” stage could have been introduced to the app, in which people deemed to have an interim degree of risk would be guided to get a PCR test rather than immediately jumping to quarantine. Including this intermediate Amber Alert population could have significantly reduced the socioeconomic costs of contact tracing while retaining its epidemiological impact or could have increased its effectiveness for a similar cost. Performing analyses like this early on in the next pandemic to determine how it is transmitted might minimize illness and strain on society.

Nature, 2023.  DOI:  10.1038/s41586-023-06952-2

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Human brain cells put much more energy into signaling

Biology, brain, frontal cortex, nerve cells, neurobiology, Science, signaling / /

Being human is hard —

Signaling molecules help modulate the brain’s overall activity.

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Image of a person staring pensively, with question marks drawn on the wall behind him.

Indian elephants have larger brains than we do (obviously). Mice have a higher brain-to-body mass ratio, and long-finned pilot whales have more neurons. So what makes humans—and more specifically, human brains—special?

As far as organs go, human brains certainly consume a ton of energy—almost 50 grams of sugar, or 12 lumps, every day. This is one of the highest energy demands relative to body metabolism known among species. But what uses up all of this energy? If the human brain is the predicted size and has the predicted number of neurons for a primate of its size, and each individual neuron uses comparable amounts of energy to those in other mammals, then its energy use shouldn’t be exceptional.

The cost of signaling

A group of neuroscientists speculated that maybe the amount of signaling that takes place within the human brain accounts for its heightened energy needs. A consequence of this would be that brain regions that are more highly connected and do more signaling will use more energy.

To test their hypothesis, the scientists started by imaging the brains of 30 healthy, right-handed volunteers between 20 and 50 years old. The imaging took place at two separate institutions, and it allowed the researchers to correlate a given brain region’s energy use (as measured by glucose metabolism) with its level of signaling and connectivity. They found that energy use and signaling scaled in tandem in all 30 brains. But certain regions stuck out. Signaling pathways in certain areas of the cortex—the front of the brain—require almost 70 percent more energy than those in sensory-motor regions.

The frontal cortex is one of the regions that expanded the most during human evolution. According to Robert Sapolsky, “What the prefrontal cortex is most about is making tough decisions in the face of temptation—gratification postponement, long-term planning, impulse control, emotional regulation. The PFC is essential for getting you to do the right thing when it is the harder thing to do.” This is the stuff that humans must constantly contend with. And energetically, it is extraordinarily costly.

Increased modulation is also key for cognition

It is not only signaling that takes energy; it is modulating that signaling, ensuring that it occurs at the appropriate levels and only at the appropriate times.

Using the Allen Human Brain Atlas, these researchers looked at gene activity in the frontal cortex. They found elevated activity of neuromodulators and their receptors. The authors note that “the human brain spends excessive energy on the long-lasting regulation of (fast) neurotransmission with (slow) neuromodulators such as serotonin, dopamine, or noradrenaline.” And also endogenous opiates. “This effect is more about setting the tone of general excitability than transferring individual bits of information,” they write.

Once they correlated energy use to signaling and slow-acting neuromodulation in the cortex, the last thing the scientists did was look at the Neurosynth project, which maps cognitive functions to brain regions. Lo and behold, the energy-hogging, highly connected, strongly modulated, and evolutionarily expanded parts of the cortex are the same ones involved in complex functions like memory processing, reading, and cognitive inhibition. This supports their idea of “an expensive signaling architecture being dedicated to human cognition.”

Science Advances, 2023.  DOI: 10.1126/sciadv.adi7632

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what-happens-in-a-crow’s-brain-when-it-uses-tools? 

What happens in a crow’s brain when it uses tools? 

Behavioral science, Biology, birds, Crows, neurobiology, Science, tool use / /

This is your brain on tools —

Researchers trace the areas of the brain that are active when birds are using tools.

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Three crows on the streets in the foreground with traffic and city lights blurry in the background.

Enlarge / Sure, they can use tools, but do they know where the nearest subway stop is?

“A thirsty crow wanted water from a pitcher, so he filled it with pebbles to raise the water level to drink,” summarizes a famous Aesop Fable. While this tale is thousands of years old, animal behaviorists still use this challenge to study corvids (which include crows, ravens, jays, and magpies) and their use of tools. In a recent Nature Communications study, researchers from a collaboration of universities across Washington, Florida, and Utah used radioactive tracers within the brains of several American crows to see which parts of their brains were active when they used stones to obtain food from the bottom of a water-filled tube.

Their results indicate that the motor learning and tactile control centers were activated in the brains of the more proficient crows, while the sensory and higher-order processing centers lit up in the brains of less proficient crows. These results suggest that competence with tools is linked to certain memories and muscle control, which the researchers claimed is similar to a ski jumper visualizing the course before jumping.

The researchers also found that out of their avian test subjects, female crows were especially proficient at tool usage, succeeding in the challenge quickly. “[A] follow-up question is whether female crows actually have more need for creative thinking relative to male crows,” elaborates Loma Pendergraft, the study’s first author and a graduate student at the University of Washington, who wants to understand if the caregiving and less dominant role of female crows gives them a higher capacity for tool use.

While only two species of crow (the New Caledonian crow and the Hawaiian crow) inherently use twigs and sticks as foraging tools, this study also suggests that other crow species, like the American crow, have the neural flexibility to learn to use tools.

A less invasive look at bird brains

Due to their unique behaviors, complex social structures, and reported intelligence, crows have fascinated animal behavioralists for decades. Scientists can study crows’ brains in real time by using 18F-fluorodeoxyglucose (FDG), a radioactive tracer, which the researchers injected into the crows’ brains. They then use positron emission tomography (PET) scans to see which brain areas are activated during different tasks.

“FDG-PET is a method we use to remotely examine activity throughout the entire brain without needing to do any surgeries or implants,” explained Pendergraft. “It’s like [a functional] MRI.” The FDG-PET method is non-invasive, as the crows aren’t required to sit still, which minimizes the stress the crows feel during the experiment.  In the Nature Communications study, Pendergraft and his team ensured the crows were anesthetized before scanning them.

FDG is also used in various medical imaging techniques, such as diagnosing Alzheimer’s disease or screening for cancerous tissue. “Basically, the body treats it as glucose, a substance needed for cells to stay alive,” Pendergraft added. “If a body part is working harder than normal, it’s going to need extra glucose to power the additional activity. This means we can measure relative FDG concentrations within the brain as a proxy for relative brain activity.”

What happens in a crow’s brain when it uses tools?  Read More »

worm’s-rear-end-develops-its-own-head,-wanders-off-to-mate

Worm’s rear end develops its own head, wanders off to mate

Biology, developmental biology, Science, worms / /

Butt what? —

The butt even grows its own eyes, antennae, and brain.

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Three images of worm-like organisms.

Enlarge / From left to right, the head of an actual worm, and the stolon of a male and female.

Some do it horizontally, some do it vertically, some do it sexually, and some asexually. Then there are some organisms that would rather grow a butt that develops into an autonomous appendage equipped with its own antennae, eyes, and brain. This appendage will detach from the main body and swim away, carrying gonads that will merge with those from other disembodied rear ends and give rise to a new generation.

Wait, what in the science fiction B-movie alien star system is this thing?

Megasyllis nipponica really exists on Earth. Otherwise known as the Japanese green syllid worm, it reproduces by a process known as stolonization, which sounds like the brainchild of a sci-fi horror genius but evolved in some annelid (segmented) worms to give future generations the best chance at survival. What was still a mystery (until now) was exactly how that bizarre appendage, or stolon, could form its own head in the middle of the worm’s body. Turns out this is a wonder of gene regulation.

Butt how?

Led by evolutionary biologist and professor Toru Miura of the University of Tokyo, a team of scientists discovered the genetic mechanism behind the formation of the stolon. It starts with Hox genes. These are a set of genes that help determine which segments of an embryo will become the head, thorax, abdomen, and so on. In annelid worms like M. nipponica, different Hox genes regulate the segments that make up the worm’s entire body.

Miura and his colleagues were expecting the activity of Hox genes to be different in the anterior and posterior of a worm. They found out that it is actually not the Hox genes that control the stolon’s segments but gonad development that alters their identity. “These findings suggest that during stolonization, gonad development induces the head formation of a stolon, without up-regulation of anterior Hox genes,” the team said in a study recently published in Scientific Reports.

The anterior part, or stock, of M. nipponica is neither male nor female. The worm has organs called gonad primordia on the underside of its posterior end. When the primordia start maturing into oocytes or testes, head-formation genes (different from the Hox genes), which are also responsible for forming a head in other creatures, become active in the middle of the stock body.

This is when the stolon starts to develop a head. Its head grows a cluster of nerve cells that serve as a brain, along with a central nervous system that extends throughout its body. The stolon’s own eyes, antennae, and swimming bristles also emerge.

Left behind

Before a stolon can take off on its own, it has to develop enough to be fully capable of swimming autonomously and finding its way to another stolon of the opposite sex. The fully developed stolon appears like an alien being attached to the rest of the worm’s body. Besides its own nervous system and something comparable to a brain, it also has two pairs of bulging eyes, two pairs of antennae, and its own digestive tube. Those eyes are enlarged for a reason, as the gonad will often need to navigate in murky waters.

The antennae of the stolon can sense the environment around them, but the researchers suggest that they have a more important function—picking up on pheromones released by the opposite sex. The stolon still isn’t an exact duplication of the stock. It doesn’t have some of the worm’s most sophisticated features, such as a digestive tube with several specialized regions, probably because its purpose is exclusively to spawn. It dies off soon after.

So what could have made stolonization evolve in the first place? Further research needs to be done, but for now, it is thought that this strange capability might have shown up in some annelid worms when genes that develop the head shifted further down the body, but why this shifting of genes evolved to begin with is still unknown.

The worm also regenerates stolons at a high rate, which may also give it the best chance at propagating its species. Hold onto your butts.

Scientific Reports, 2023.  DOI:  10.1038/s41598-023-46358-8

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