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Category: Animals

All animals play essential roles in ecosystems and captivate us with their beauty and fascinating characteristics.

  • The Difference Between Chimpanzee and Bonobo

    The Difference Between Chimpanzee and Bonobo

    Although both chimpanzees and bonobos are members of the great ape family of the genus Pan, they are distinguished from one another in appearance and behavior. Pan troglodytes refers to the common chimpanzee (which encompasses four distinct chimpanzee subspecies), whereas Paniscus is the name given to bonobos.

    These apes, which are genetically quite similar to one another, split into two separate species around 1.5–2 million years ago, when the Congo River separated them geographically.

    The variations in appearance, diet, and sexual behavior grew increasingly obvious after that. Sadly, chimpanzees and bonobos have something in common. The International Union for the Conservation of Nature has designated both species as endangered due to human activities such as poaching and the destruction of their natural habitats.

    When Comparing Chimpanzees With Bonobos, There Are Several Noticeable Physical Distinctions

    A bonobo family
    A bonobo family

    When they reach adulthood, chimpanzees and bonobos have many distinct physical characteristics. Both have black fur and skin, hair everywhere except the feet, hands, and face, and disproportionately huge arms. Chimpanzees’ faces are pink while they are young and become brown as they age. Chimpanzees have noticeably bigger ears than humans do.

    The bonobo is not much smaller than its close relative, the chimpanzee, despite its other name, “pygmy chimpanzee.” Bonobos average roughly 40 inches (100 cm) in length and 81–88 pounds (37–40 kg) in weight, whereas chimpanzees may reach 47 inches (120 cm) in length and 88–110 pounds (40–50 kg) in weight. The bonobo gives off an air of deceptive fragility due to its smaller head and neck.

    Finally, the two relatives’ modes of movement are distinct from one another. While the bonobo is nimble on two legs, the chimpanzee is more comfortable moving about on four.

    Notable Variations in Habitat, Way of Life, and Sexuality

    A chimpanzee family
    A chimpanzee family

    From Senegal to South Africa, the chimpanzee may be found in a total of 21 African nations. The bonobo only lives in the wet woods of the southern Democratic Republic of the Congo.

    The bonobo follows a plant-based diet, whereas the chimpanzee eats a variety of foods.

    These two ape species are unique in that they are social animals. Nonetheless, they are not subject to the same regulations. To begin, unlike bonobos, where the females have the upper hand, chimpanzee males are the dominant force.

    Also, bonobos and chimpanzees use their sexuality in different ways. Bonobos use sex to settle disagreements (both between males and females and between the same sexes), while chimpanzees use physical force and aggression to show who is in charge.

    Sources:

  • Where Do Mosquitoes Go in the Winter?

    Where Do Mosquitoes Go in the Winter?

    In the evening, with pleasant weather, it doesn’t take long until you find yourself relaxing on the patio, taking in the sun, or enjoying a BBQ. But then, you are startled by a painful sensation on your arm, which is immediately followed by severe itching. The blood was drawn out by the lengthy proboscis of a mosquito that just bit you. Throughout the spring, summer, and autumn, it is almost impossible to get rid of mosquitoes, even with the use of pricey mosquito repellents. But, during the winter, you never see or hear anything about them. Where do mosquitoes go in the winter? And what do they do at this time of year?

    Unlucky Males

    The mosquito, like other insects, is a cold-blooded species. They have no control over their body temperature, which is always the same as their environment. The optimal temperature for mosquitoes is around 78 degrees Fahrenheit (25ºC), and at 60 degrees Fahrenheit (15ºC) the insects slow down, and anything below 50 degrees Fahrenheit (10ºC) makes them almost dead.

    The thing is, the male mosquitoes can’t survive the winter. In fact, they already die away by fall. Males do not feed on blood, and their proboscis is not powerful enough to puncture your skin and bite you.

    They consume nothing other than nectar and the fluids of plants. Blood is one of the several nutrients that only females are required to provide for their kids. It is specifically these female mosquitoes that are able to endure the dip in temperature during the winter.

    Mosquitoes Craft Their Own Anti-Freeze

    Aedes aegypti mosquito larvae.
    Aedes aegypti mosquito larvae.

    The female mosquitoes may find the best chance to survive throughout the winter months in locations like basements, caverns, cow barns, and buildings since these areas are cool, wet, and sheltered. There, the insects enter a state of inactivity, also known as torpor, caused by the dropping temperatures.

    For the mosquitoes to be prepared for this, during evolution, they have created an odd adaptation mechanism: they begin by eliminating a fluid from their bodies via excretion. After that, sugar is added to this liquid which together acts like an antifreeze covering the mosquito’s body. The females emerge from their torpor when the weather begins to warm up again in the spring and start laying their eggs.

    Mosquito Eggs Survive in the Mud

    The frost very rarely kills adult female mosquitoes or their egg clutches that have already been laid in water bodies such as lakes, ponds, or rain barrels in the autumn. As long as the mud does not freeze, the mosquito eggs survive the winter in the mud on the bottom of a body of water without any issues.

    The conditions throughout the spring and summer are what ultimately determine whether or not there will be a mosquito infestation. For instance, prolonged periods of rainfall provide the larvae with optimal breeding grounds. If warm temperatures are coupled with this, the conditions become ideal for a mosquito invasion.

    However, it is possible to be bitten by a mosquito even during the wintertime. Because if a mosquito is able to find its way into a heated home, then that is where it will continue to live for a while. Yet, there is a good chance that it will die over the winter season while in there.

    Sources:

  • Are Thrips Really the Indicator of Thunderstorms?

    Are Thrips Really the Indicator of Thunderstorms?

    Thunderstorm creatures, also known as thrips or fringed-wing insects, are often little, black, and very unpleasant. They are often called thunderflies, thunderbugs, storm flies, thunderblights, or storm bugs. These tiny insects, which rarely exceed 0.12 inches (3 millimeters) in length, seem to arrive en masse if the weather is hot and humid and a rainstorm is on the horizon. Although there are over 6,000 different species of thrips, their tiny size means they are often overlooked.

    When Thrips Cluster in Thousands

    Thunderstorm
    (Image: Fort Valley State University)

    They cluster together in the thousands, resembling dark clouds, which are unpleasant for anybody who is caught in them because the thrips fall on any exposed skin and also in the nasal passages, oral cavity, and eyes, producing a crawling, itchy sensation. But may the reason for their mass hording be the approaching thunderstorm? Are they really suitable as thunderstorm indicators? If that’s the case, then how can thrips anticipate the arrival of a thunderstorm?

    On hot, humid summer days, several species of thrips are known to engage in swarming flights. Temperatures over 70 degrees Fahrenheit (20 degrees Celsius) and stable, unchanging climatic conditions trigger the huge swarming of thrips. Thrips may rapidly become a nuisance when they emerge in masses, landing on humans and being drawn to all bright colors. When it’s hot and steamy outside, humans sweat, and thrips lick this perspiration off their skin and sometimes even bite through it. This causes irritation and, in really sensitive individuals, skin inflammation.

    Humans as Landing Pands

    But the thunderstorm is not the cause of the thrips’ mass presence. Instead, the little insects, which are normally dispersed across the skies, settle on the ground in a coordinated effort when a storm is approaching. So they cluster around the places where people like us go and even utilize us as landing pads.

    Thus, an increase in the number of thrips in the lower levels of the atmosphere may actually be an indicator of an approaching thunderstorm.

    Electric Field as a Thunderstorm Indicator

    However, how can thrips know when a storm is about to hit the area? This is more related to a physical phenomenon than the weather itself. This is because electrically charged thunderclouds also alter the atmospheric electric field. Thunderstorms may produce electric fields as strong as 15 kilovolts per foot (kV/ft) (50 kilovolts per meter), compared to the typical 0.03 kV/ft (0.1 kV/m).

    Research on fruit flies and other insects demonstrates that strong electric fields may cause thrips to lose control of their flight and become disoriented. For instance, British thrips researcher William Kirk believes that tiny insects like thrips, in particular, are impacted by variations in electric field strength and are no longer able to fly at roughly 2.4 kV/ft (8 kV/m) and beyond. So, this electric charge might also be responsible for the sudden swarms of thrips that arrive near the ground just before a rainstorm. In most cases, though, it appears that thrips swarms are indicators of an impending storm.

  • Moles Shrink Their Brains in the Winter

    Moles Shrink Their Brains in the Winter

  • Why Do Butterfly Wings Change Color?

    Why Do Butterfly Wings Change Color?

    Some of nature’s most eye-catching displays of color may be seen on the wings of butterflies. They have spots that are green, blue, or red, and they appear to change color as they move. Morpho rhetenor is a butterfly native to tropical regions with a brilliant blue coloration that can be seen from more than half a mile away. The work of British physicist Peter Vukusic has led to this conclusion. But where does this brilliant glow exactly come from?

    Pigments are what give flowers, fur, and most other common items their colors. They seem to be different colors because they reflect just part of the visible spectrum. But butterflies and the ones that glisten in the sunlight are different from other insects. Most of the time, they lack any visible pigments. But what causes them to glow in the first place?

    The famous scientist Isaac Newton began to suspect something was amiss as early as 1672. As far as he could tell, insects use small physical structures to influence light. We now know that the anatomy of a butterfly’s wing holds the key to understanding the iridescent colors it displays.

    Reminiscent of Roof Shingles

    Why do butterfly wings change color?

    Butterflies have thousands upon thousands of tiny, overlapping scales covering their wings. These scales are 1–3 micrometers thick and laid out in a pattern reminiscent of roof shingles. Each scale is constructed from a number of very thin layers of keratin. The protein keratin is also found in hair and fingernails. There is a minimal amount of space between each keratin layer.

    The topmost of these transparent layers reflect some of the light that penetrates them. Keratin is penetrated by the rest. Another portion of the light is reflected from its underside as it travels through the air. Light waves that are reflected from the wing undergo a little redistribution as a result of this offset reflection. The two reflected waves no longer have parallel troughs (dips) and crests (peaks).

    Scientists liken it to the action of waves on a small channel between two harbors: Sometimes a bigger wave is formed when the crests of two waves collide. And sometimes a crest and trough cancel each other out.

    The nanostructure of the scales on a butterfly wing makes some colors and wavelengths of light more intense than others.

    Butterfly Colors Change Due to Directional Reflection

    However, the wing scales are capable of doing more, since each individual layer selectively emits the reflected light. That’s why the butterfly wing might seem brilliant blue one moment and subtly green the next time you look at it.

    Generally speaking, pigment colors don’t shine very brilliantly due to their inefficient light reflection. By reflecting light in a specific fashion, structural colors like the ones seen on butterflies may achieve extremely high and varying intensities. Thanks to these, the male butterfly in the morphed form can still attract females from hundreds of feet away with its dazzling blue display.

  • How Many Ants Are in the World?

    How Many Ants Are in the World?

    Biologists have estimated that there are at least 20 quadrillion ants in existence on Earth, or around 2.5 million ants for every human being. This means that the total dry biomass of all ants exceeds that of all birds and wild animals put together. The subtropical and tropical areas have the highest ant density, yet the ant world map still has a lot of blank spaces.

    Ants are common in practically every environment, including forests, gardens, and cities. While scientists have documented and named over 15,700 different species of social insects, they suspect the number is really closer to 30,000. Ants are crucial in the breakdown of organic matter because they are aphid or fungus producers as well as a source of food for a wide variety of birds, arthropods, and mammals.

    Ant Population Count

    But how many ants exist on a global scale? So far, estimates of ant population size have been made only on a rough scale, using methods such as local sampling or the fact that ants account for just a fraction of the world’s insect population (1%). Estimates have varied greatly in the past because of the large number of unknown variables involving the frequency and variety of insects. As a result, the “census” of the world’s ant population was conducted in a novel way by a group headed by Patrick Schultheiss of the Universities of Hong Kong and Würzburg.

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    The scientists looked at information from 465 studies from all around the globe that counted ants by taking soil litter samples or by using ground traps. The second technique was examined independently from the former since it represents activity rather than absolute numbers of ants in a region. Also included were results from 24 research that sprayed whole tree canopies with pesticide to determine ant populations.

    Worldwide, There Are Around 20 Quadrillion Ants

    It is estimated that there are three quadrillion ants in the world’s ground litter. The ants in the litter are only a small sample of the whole ant population. The overall number of ants, including those in various environments, is estimated to be roughly 19.8 quadrillions (that makes 19,800,000,000,000,000). That means there are around 2.5 million ants for every human being on Earth.

    Even though each ant weighs almost nothing, the total dry biomass of all ants adds up to around 12.

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    3 megatons of carbon, according to the study’s authors. This represents almost 20% of the total human dry biomass and is comparable to the total dry biomass of all wild birds and animals.

    Especially In the Tropics

    Ants, however, are not uniformly dispersed throughout all temperate zones and ecological zones: Remarkably, just two biomes—tropical rainforests and tropical savannas—are home to more than half of the world’s ant population.

    Results from the scatterplots show that the abundance of ants is two times as high in subtropical and tropical ecosystems as it is in temperate ones. Ant activity in tropical and subtropical regions could be three to four times greater than in temperate regions. This demonstrates how crucial tropical areas are to the worldwide quantity and biomass of ants.

    Omnivorous Ant-Eaters From All Corners of the World

    A large number of mammalian species, particularly in the tropics, have adapted to rely on ants as a primary food source. The anteaters of South America, the pangolins of Southeast Asia, and the aardvarks of Africa have all separately acquired specialized adaptations that allow them to dig up ant nests and gather the ants with their insensate, long tongues.

    To escape being eaten by ants or to be able to feed on them directly, more arthropods copy ant behavior or morphology in the tropics since ants are more prevalent there and mimicry is thus more successful there.

    The Real Figure Is Significantly Higher

    Indeed, the new study has improved our understanding of the staggering magnitude of the ant population on Earth. However, the group emphasizes that these numbers represent a cautious assessment. The number of unreported instances is likely considerable since there are numerous habitats and biomes for which very little data is available. Examples of such biomes and habitats include subterranean habitats, mangroves, and boreal woods.

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    There is also a lack of data from Africa and Central Asia.

    For this reason, the estimated global ant population likely understates the genuine amount by a significant margin. To acquire a fuller understanding of ant diversity and patterns of global biodiversity, their causes, and their implications, there is so much more work to do.

    Sources:

  • Can Frogs Really Predict the Weather?

    Can Frogs Really Predict the Weather?

    Frogs are weather experts. Some frogs and toads, based on their croaking, egg-laying, and even skin color, are said to allow us to predict whether it will rain soon or not. But what is the truth behind the frogs’ purportedly preternatural weather forecasting abilities?

    Long ago in Switzerland, if you would put a tree frog in a jar half full of water and give it a little ladder to climb, it could forecast good weather by climbing the ladder and bad weather by descending back into the water. Even today, in Germany, a weatherman is referred to as a Wetterfrosch, which translates as “weather frog.”

    Tree frogs are known to climb trees in favorable weather and make an awful noise, croaking sweetly for hours on end, thus the frog weather prediction theory actually has some validity.

    Monitoring the Humidity

    Numerous accounts point out the daily behavioral changes in amphibians and some reptiles related to predicted weather. Some species, for instance, become more active just before it starts to rain, while others are more likely to make their distinctive croaking sounds. The weather probably has a lot to do with this shift in behavior.

    Frogs and toads are highly reliant on accurately monitoring the humidity or temperature of their surroundings. That’s because amphibians are ectothermic, meaning they don’t produce their own heat. So, their blood, muscles, and skin, along with the rest of their organs, are always at the same temperature as their surroundings.

    Exceptionally Sensitive to Moisture Levels

    Frogs’ skin is very porous because of the abundance of glands on its surface. Because of this, they suffer significant water loss due to evaporation. But frogs and toads have a more refined sense of moisture via their skin than people do. In the tropics, for example, certain frog species usually come out of the underbrush when the humidity rises in anticipation of rain.

    Finally, amphibians like frogs and toads produce their offspring in aquatic environments. Thus, in order to effectively reproduce, they have to predict when there will be adequate puddles and pools from rain in which their tadpoles may grow. This means that when the weather or temperature changes, frogs have to adjust their behavior accordingly.

    Climbing Tree Frog

    So why then do frogs choose to remain low when bad weather is approaching, yet climb up when conditions are favorable? There are no precise investigations of the topic available. However, there are two theories among frog scientists as to why this occurs: The tree frog, in contrast to most other frog species, enjoys vertical environments and bright sunlight. Male frogs, especially those still in their juvenile stages, spend most of the late summer sitting on bushy branches and leaves to soak up some rays.

    However, the accessibility of food is equally important. The same goes for tree frogs, who also utilize their perches to swoop down on prey. Insects like mosquitoes are sensitive to weather changes, something our ancestors accounted for in their agricultural guidelines. With less wind and more sunshine, insects may ride the warm updrafts to greater heights in their flights. They tend to linger on the ground if a severe wind and a drop in temperature are expected.

    It is unknown, however, whether tree frogs actively pursue prey higher or lower, or if they instead respond immediately to changes in the weather. One thing scientists can agree on is that frogs and toads frequently respond to a shift in the weather before humans do. And this, of course, has nothing to do with clairvoyance.

  • Why Do Hagfish Tie Themselves In Knots?

    Why Do Hagfish Tie Themselves In Knots?

  • Are Mosquitos a Threat in the Near Future?

    Are Mosquitos a Threat in the Near Future?

    In many different countries, mosquito infestations occur at various times of the year. The ones that occur throughout the summer originate from the ideal breeding conditions, which end with an explosion in the mosquito population. The itching and discomfort caused by mosquito bites are indisputable. When you scratch the bite, you irritate the surrounding tissue, which leads to the development of a red, raised lump on the skin. If you are bitten by a mosquito, does it mean that you are also at risk of contracting a disease?

    The Rise in Animal Transmitted Diseases

    The incidence of diseases transmitted by animals is growing at an alarming rate around the world, especially in the Far East. In the past, residents of Central Europe have been diagnosed with malaria despite having never left the area where they live. But veterinarians and other specialists believe that there is currently no cause for concern in this region for mosquito infection.

    Researchers discovered a few cases of virus transmission in the previous year, despite the unusual nature of the transmission. The Sindbis virus is a mildly dangerous virus that can occasionally result in meningitis. It is carried by the common Culex pipiens mosquito.

    However, the population of the Asian bush mosquito, also known as Aedes japonicus, is increasing at an alarming rate, especially across Central Europe. Throughout the past few years, areas that encompass a land area of approximately 2,000 square kilometers have been plagued by an extremely active vector of diseases such as the West Nile virus. It wasn’t until the year 2012 that researchers were able to prove that a breeding population of this particular species of mosquito had indeed been established in Europe.

    The Asian tiger mosquito, scientifically known as Stegomyia albopicta, has already established a breeding population in the area. The bloodsucker known to carry exotic diseases has been linked to the transmission of viruses, including West Nile and tropical dengue fever. In recent years, the mosquitoes that are responsible for transmitting the dengue and chikungunya viruses to people have been discovered in southern Europe.

    Dog Tapeworm Is Carried by Mosquitoes

    The larvae of the canine tapeworm, Dirofilaria repens, were found for the first time in Europe. This part of the world did not have any previous encounters with the parasite until very recently. Although mosquitoes are the most likely vector for transmission of these parasitic worms to humans, dogs continue to be the most common hosts for them. As of yet, there have been no reports of human illnesses acquired in the area.

    Researchers have detected larvae of the dog skin worm Dirofilaria repens in mosquitoes for the first time in Central Europe. The parasite was previously not native to the land. Parasitic worms are found in dogs, but in rare cases, mosquitoes also transmit the infection to humans. So far, however, no human infections acquired in the area.

    So, people are still relatively safe for the time being. However, if global temperatures continue to rise this may change in the future.

    Sources:

  • What Do Drone Bees Do Anyway?

    What Do Drone Bees Do Anyway?

    The bee colony lives under the slogan “All for one, one for all.” There are between 30,000 and 80,000 individual bees in a hive, and none of them could survive on their own. The only thing that assures the insect population will continue to exist is the perfect division of work inside the hive. The queen bee is primarily responsible for reproduction at all times.

    On the other hand, the worker bees are responsible for all of the other tasks, including the care of the young, the collection of food, and the protection of the nest. However, the male bees, often known as drones, do not seem to contribute much to the common good and would rather have their needs met. The only duty they have is to mate with the queen, and this happens over and over again. But should we really believe that? Are drones as lazy as they seem?

    When considering the number of forays they make each day, bees as a species might be characterized as “lazy.” On the other hand, the honey bee colony functions as a superorganism that is very hardworking. Every day, bees are responsible for pollinating several million flowers.

    The Main Role of Drone Bees

    But what exactly are drones responsible for in a bee colony? It is not possible for drones to gather nectar and pollen, construct honeycombs, or feed babies.

    A bee colony uses drones to spread its genetic material. The physical effort drone bees make during their multiple mating flights is extraordinary. That’s why they are actually diligent. That’s why drones cannot eat themselves and must be fed by workers throughout their lives.

    Temperature Control and Communication

    Simply by being in the hive, drones perform an essential role in the process of temperature control. Their bodies provide insulation, and they have the ability to create heat via the use of their flight muscles. But there is little doubt that the drones also played some part in the intricate communication system that the bees used.

    They Die From Not Being Fed

    Drone bees seem to be employed not just as sperm banks, but also for a variety of other important hive tasks. Despite this, they do not get a lot of appreciation for doing what they are doing. Drone bees face a hasty demise after the conclusion of the mating season, which occurs in August and September at the very latest. 

    After then, they have fulfilled their purpose and are no longer fed by the workers; the drones are destined to perish from hunger. They often pass away within the hive, and their bodies are then removed.

    Even more, worker bees regularly stab drones that are still living.

  • How Powerful Were Saber-Toothed Cats?

    How Powerful Were Saber-Toothed Cats?

  • Are Snails Really Slow? How Fast Are They?

    Are Snails Really Slow? How Fast Are They?

  • How Come Earthworm Can Still Live After Splitting In Half?

    How Come Earthworm Can Still Live After Splitting In Half?

    Earthworms are disliked by a large number of humans, and birds like eating them since when it rains, they will often abandon their underground habitat. The common earthworm is known in Latin by the name Lumbricus terrestris. These animals have strange characteristics that many people witnessed as children: You can slice through the worm with a pointed shovel, but both ends of the earthworm’s body will continue to move around. The worm has the ability to recreate the lost part of its body entirely. But how does this even happen in the first place?

    The Location of the Cut Matters

    How come earthworm can still live after splitting in half?
    (Credit: Addison Wesley Longman)

    Even though it is missing a significant portion of its body, the worm is nonetheless able to live on. The earthworm has the ability to regenerate the lost section of its body. However, it seems to make a difference where on the worm the cut was made.


    Only the front portion that contains the mouthparts can be regenerated, and this can only happen if only a few segments are lost. The head of the worm is where the digestive system and the central brain are found.

    Surviving Without A Head

    Yet, it is still possible to encounter surviving rear ends that do not have a head. Due to the fact that a worm without its head is unable to eat effectively, it can only have a short lifespan in this scenario. This rare phenomenon happens as a result of both ends being genuinely capable of regeneration. However, the rear end can only give birth to another rear end; hence, all of the vital organs that are located in the front section are lost. The front end, on the other hand, has the capability of regenerating a new rear end and creating a whole worm in this way.

    Still, there is a low chance that these damaged worms will be able to live in the wild because of infections in their wounds.

    How Does An Earthworm Regenerate Its Missing Part?

    It is known that approximately a week is required for the worm to develop its missing body section. During this period of time, a wound layer will begin to develop on the end. Cells from the gut and the skin move into the damaged area to begin the process of progressively forming the new body segments.


    The segments on the rear end regenerate quicker than those on the front. Additionally, the rear replacements are narrower, at least at the beginning of the regeneration.

    It takes about two to three months for the pigmentation of new segments to return to the worm’s true color.

    How Earthworm Still Moves After Being Cut Off

    The separated ends of an earthworm’s body may appear to crawl around so deftly. This phenomenon has a biological cause as well: Earthworms have what is referred to as a “ladder-like” nervous system, which, as the name implies, goes through the whole body similar to a rope ladder. The pain causes the earthworm’s flight instinct to be activated, and it does so whether the worm is only squeezed or entirely cut. This response causes muscular twitching, which is why the earthworm appears to crawl around after being cut. However, if the shovel strikes the earthworm in the wrong spot, the animal may not regenerate from it.

  • Why Do Some Female Spiders Eat Their Mates?

    Why Do Some Female Spiders Eat Their Mates?

    Why do some female spiders eat their mates? You frequently hear the words “I love you so much” said between people newly in love. However, there are certain creatures who take this remark to a new level. They eat members of their own species, sometimes even when they’re mating. Particularly, spiders have a bad name for engaging in “sexual cannibalism.” The black widow spider has gained as much notoriety as the red-backed spider and the native cross spider for its reputation as a predator of male humans. Nevertheless, why do female spiders kill and eat males?

    Sexual Cannibalism

    Sexual cannibalism may be split into two distinct subtypes. The first involves females eating a male before mating, either out of hunger or to prevent mating. This is a common occurrence in a wide variety of animal species. However, this only applies to a tiny fraction of males and is by no means the norm.

    Sexual cannibalism also occurs during and immediately after the mating act. Scientists have discovered that females of certain species will systematically murder males if they so desire. For instance, Latrodectus hasselti, known as the Redback spider or the Australian black widow spider, and Argiope spiders fall within this category. Wasp spiders, recognizable by their striped abdomen of yellow, white, and black, are also members of this family.

    The Reason

    But why would the supposedly cruel and merciless female spiders engage in such strange behavior? They do this so that they may continue mating with different males while keeping the duration of copulation, or sexual intercourse, to a minimum. Finding a mate with the finest genes to inseminate the eggs is the main objective of mating for female spiders.

    In addition, the male spider makes a pleasant source of food and energy for females when consumed after being slain. There is a clear advantage to the children from this as well. Studies have shown that female spiders that consume males have bigger clutches (total number of eggs) than female spiders who are not allowed to consume males.

    Mating Length is the Key Factor

    Even yet, some male spiders still make it through the initial mating without being attacked by the female spiders. Variation exists even within species when it comes to the mortality rate of males following the first successful mating. Males that don’t mate for long enough are also at a higher risk of being eaten.

    Those males who get out of the encounter unharmed, however, don’t attempt to get away and instead go through with a second mating, which almost always ends in tragedy. Unfortunately, this still raises one’s odds of becoming a father and having offspring. When a male tries to push his luck and, in the end, sacrifices himself, this still lets him fertilize more of the female’s eggs.

    Before making love, the St. Andrews Cross spider (Argiope keyserlingi) uses a webbing to tie its mate to itself. Keeping the male around for longer may be desirable from the female’s perspective if she hopes to increase the number of eggs that are fertilized.

    Mates With Smaller Sizes Are More Likely to Be Eaten

    However, sexual cannibalism in spiders does not always seem to be caused by competition for evolutionary benefit. Researchers claim to have identified an alternative cause for this behavior. They claim that when men are physically inferior to their female companions, they are more likely to be eaten. This is true of many species, including the North American wolf spider, Tigrosa helluo.

    It is interesting to see that a seemingly insignificant factor—the size gap between sexes—plays such a crucial role in determining sexual cannibalism. The trade-offs involved in sexual cannibalism are usually rather simple. When a hungry female spider comes upon a “boyfriend” tiny enough to trap, she can’t stop the urge.

    Praying Mantises Also Show This Behavior

    The practice of eating and being eaten is not limited to the sexual partners of spiders. Scientists have known for a long time that the phenomena occur in various clades of animals. Some insects, including praying mantises, have earned a reputation for this behavior. These insects’ males have a very perilous existence before, during, and after mating. One Asian species, Hierodula membranacea, has females that have been seen biting off the males’ heads during intercourse; however, the sexual act continues undisturbed.

    Sources:

    • Sexual Cannibalism: Why Females Sometimes Eat Their Mates After Sex. (n.d.). Discover Magazine.
  • How Rabbits Came to Australia

    How Rabbits Came to Australia

    Australian wild rabbits are regarded as an invasive species. But how and when did their forebears enter the continent? DNA testing reveals that all Australian rabbits are descended from a single import.

    It seems that Australia’s ongoing rabbit infestation was started by a single English settler. According to genetic testing, the 24 individuals that Englishman Thomas Austin sent to the newly discovered continent in 1859 are the ancestors of all current Australian rabbits. Rabbits that had previously been imported, however, did not seem to be able to develop into an invasive species.

    In Australia, rabbits are regarded as the best illustration of an invading species. These herbivores, which were brought to the continent by English immigrants but were not indigenous to Australia, proliferated quickly. They still pose a menace to local animals and vegetation and yearly result in agricultural loss of over $200 million. The introduction of the myxomatosis virus, which was supposed to kill the rabbits, and other control techniques failed to achieve the expected results.

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    Across the Continent

    However, how did the rabbit invasion start? This matter has finally been resolved by a team headed by Joel Alves from the University of Oxford utilizing genomic studies. Alves and his colleagues used historical records of introduction occasions in conjunction with genetic analysis to integrate the results from 187 rabbits taken between 1865 and 2018 in Australia, Tasmania, New Zealand, the United Kingdom, and France.

    The historical records show that the British fleet’s ships brought the first five domestic rabbits to mainland Australia as early as 1788. At least 90 other species were imported during the next 70 years, but none of these populations spread aggressively. A batch of 24 rabbits were then shipped to English immigrant Thomas Austin in 1859 for his property near Geelong in Victoria. It has been debatable up until now whether one of these imports, or a combination of them, is to blame for the current rabbit infestation on the continent.

    Linkage to the Southwest of England

    The answer is now available from comparative studies of rabbit genomes. It appears that despite many introductions over a 70-year span, the invasion was started by a single release of a small number of rabbits that spread thousands of miles across the continent. Austin’s introduction of rabbits in 1859 was the main source of the current population in Australia.

    The origins of the invasive population in Australia may be traced to southwest England, when Austin’s family acquired the rabbits in 1859. In October 1859, Austin’s family gave him six wild bunnies and seven domestic rabbits, and they multiplied along the route to Australia, arriving at 24 animals, according to historical documents.

    The researchers discovered that all rabbits in Australia now do indeed contain genetic mixtures of wild and farmed rabbits, which is consistent with this account.

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    Additionally, it revealed that the area with the most genetic variety was close to Austin’s land, providing compelling evidence that this is where the population started.
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    Heritage of Wild Rabbits as a Success Factor

    But why did Austin’s rabbits manage to expand quickly across Australia when earlier imported rabbits at best created tiny local populations? The introduction of a novel genotype that was better suited to environmental circumstances was the decisive element.

    Historical records depict previously imported rabbits as domesticated pets with floppy ears and elaborate coat colors. Feral domestic rabbits may exhibit a variety of characteristics that make them ill-suited to surviving in the wild. They may not have had the genetic diversity required to endure Australia’s dry and semi-arid environment.

    In contrast, Austin’s animals were at least partially wild rabbits. So it’s plausible that Thomas Austin’s wild rabbits and their offspring had an evolutionary edge when it came to adjusting to these circumstances.

    The Past Biological Invasion

    The researchers claim that genetics has a significant impact on biological invasions, in addition to variables like environmental circumstances and the number of imported specimens. The success of biological invasions must be understood if they are to be stopped since they pose a serious danger to the world’s biodiversity.

    Australian rabbits have now succeeded in achieving this: Australia may have been more open to invasion due to environmental changes, but one of the biggest biological invasions in history was actually caused by the genetic composition of a tiny population of wild rabbits. This serves as a reminder that even a single person or a small group of people may have a significant negative impact on the environment.

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