Tag: spider

  • 9 of the Biggest Spiders in the World

    9 of the Biggest Spiders in the World

    Large spider species are found all over the world and many of them can reach quite impressive sizes. These spiders are considered one of nature’s most interesting creatures and arouse curiosity among humans. In this list, the 9 largest spiders in the world are listed in order from biggest to smallest.

    Goliath Birdeater (Theraphosa blondi)

    Goliath Birdeater (Theraphosa blondi)
    Goliath Birdeater (Theraphosa blondi). Image: Ryan Somma.

    The Goliath Birdeater is famous for its gigantic size, with a leg span that can reach up to 30 cm (12 in). It has a robust and hairy body covered in reddish-brown or dark brown fur, which gives it a distinctive and imposing appearance. Despite its intimidating size, it is important to note that the Goliath Birdeater is generally docile and not aggressive towards humans.

    These giant spiders are found primarily in the rainforests of South America, including countries such as Brazil, Venezuela, and Suriname.


    They usually live in burrows that they dig in the ground or build in hollow logs or tree roots.

    Despite its name, the Goliath Birdeater does not primarily hunt birds. Although it may occasionally eat small birds, its diet consists mostly of insects, other spiders, and small mammals.

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    It is an opportunistic hunter and ambushes prey that get too close to its nest.

    These spiders are nocturnal, meaning they are most active at night. Goliath Birdeaters are known for their unique defense mechanism, where they can grow creepy hairs from their abdomen when threatened. These prickly hairs can cause irritation to the skin and eyes of potential predators.

    While female Goliath Birdeaters can live for decades, males have a much shorter lifespan. Mating involves a complex courtship ritual and males must approach females carefully to avoid being mistaken for prey.

    Giant Huntsman Spider (Heteropoda maxima)

    Giant Huntsman Spider (Heteropoda maxima)
    Giant Huntsman Spider (Heteropoda maxima). Image: Laotische Riesenkrabbenspinne.

    The Giant Hunter Spider is one of the largest spiders in the world, with a leg span that can reach up to 30 cm (about 12 in) and long, spindly legs and a relatively flat body. This spider can vary in color but usually has a brown or reddish-brown body with mottled patterns.

    They live primarily in tropical and subtropical regions of Asia, including countries such as Laos, Vietnam, and Malaysia. They are often seen in forests, caves, and sometimes inside man-made structures.

    As the word “hunter” in their name suggests, these spiders are skilled hunters. They do not spin traditional webs to catch their prey. So spiders are agile and fast-moving hunters that can catch these animals—insects and other small invertebrates.

    Giant hunting spiders are nocturnal, meaning they are most active at night. They are known for their impressive speed and agility, which they use to catch their prey. While their large size can be intimidating, they are generally not considered dangerous to humans and are likely to flee from potential danger.

    Brazilian Salmon Pink Bird-Eating Tarantula (Lasiodora parahybana)

    Brazilian Salmon Pink Bird-Eating Tarantula (Lasiodora parahybana)
    Brazilian salmon pink tarantula (aslo birdeater) adult female (Lasiodora parahybana). Image: Public Domain.

    The Brazilian Salmon Pink Bird-Eating Tarantula is one of the largest tarantula species in the world.


    It boasts a leg span that can reach up to approximately 25 cm (10 in). The name “Salmon Pink” refers to its coloration, which typically includes a pinkish hue on its body and legs combined with brownish or grayish tones.

    These tarantulas are native to Brazil, particularly the Atlantic rainforests of the Parahyba region. They are primarily ground-dwelling, constructing burrows in the soil.

    Despite the common name, they do not primarily prey on birds. Instead, their diet mainly consists of insects, other arachnids, and small vertebrates like rodents. They are sit-and-wait predators, staying near their burrows and ambushing passing prey.

    Brazilian Salmon Pink Bird-Eating Tarantulas are typically docile and are not known to be aggressive toward humans. When threatened, they may display a threat posture, raising their front legs and showing their fangs. Like many tarantulas, they have urticating hairs on their abdomen, which can be flicked as a defense mechanism to irritate potential predators.

    Brazilian Giant Tawny Red Tarantula (Pterinopelma sazimai)

    The Brazilian Giant Tawny Red Tarantula is a relatively large tarantula species, with a leg span that can reach up to around 23 cm (approximately 9 in). Its name reflects its distinctive coloration. These tarantulas typically have a tawny or reddish-brown hue on their bodies and legs.

    These tarantulas are native to Brazil, particularly the state of Bahia, in the eastern part of the country. They inhabit tropical forests and are often found in burrows or crevices.

    Like most tarantulas, the Brazilian Giant Tawny Red Tarantula is an opportunistic predator, feeding primarily on insects, other arachnids, and occasionally small vertebrates. They are ambush predators, relying on their sit-and-wait strategy to capture passing prey.

    Brazilian Whiteknee Tarantula (Acanthoscurria geniculata)

    Brazilian Whiteknee Tarantula (Acanthoscurria geniculata)
    Brazilian Whiteknee Tarantula eating a small frog. Image: Wikimedia.

    The Brazilian Whiteknee Tarantula is a medium- to large-sized tarantula with a leg span that typically ranges from 18 to 20 cm (around 7 to 8 in). It is recognized by its distinct coloration, characterized by a dark-colored body with striking white bands or “knees,” on its legs.

    These tarantulas are primarily found in the rainforests and tropical regions of Brazil. They often make burrows in the ground, which they use as shelters and for molting.

    The Brazilian Whiteknee Tarantula is an opportunistic predator, feeding on various prey, including insects and small invertebrates. They are sit-and-wait predators, often ambushing their prey when it ventures close to their burrows.

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    Colombian Giant Redleg Tarantula (Megaphobema robustum)

    Colombian Giant Redleg Tarantula (Megaphobema robustum)
    Colombian Giant Redleg Tarantula (Megaphobema robustum). Image: Snakecollector.

    The Colombian Giant Redleg Tarantula is a large tarantula with a leg span that can reach around 20 cm (about 8 in). Its striking and distinguishing feature is its vivid coloration. These tarantulas have dark bodies with striking red hairs on their legs, giving them the “redleg” name.

    These tarantulas are native to Colombia, particularly the Andean region, but they are also found in other parts of South America. They are often discovered in mountainous areas, typically at higher elevations.

    The Colombian Giant Redleg Tarantula is a carnivorous predator, feeding on a variety of prey, including insects and small invertebrates. Like most tarantulas, they employ a sit-and-wait hunting strategy, ambushing and capturing prey that comes near their burrows.

    King Baboon Spider (Pelinobius muticus)

    King Baboon Spider (Pelinobius muticus)
    King Baboon Spider (Pelinobius muticus). Image: Wikimedia.

    The King Baboon Spider is a large and robust tarantula with a leg span that can reach around 20 cm (approximately 8 in). It is characterized by its striking coloration, with a dark brown to black body and striking yellow bands on the legs. These bright markings give it a regal appearance, hence the name “King Baboon.”

    This species is native to the tropical rainforests of East Africa, particularly in Tanzania and Kenya. They are often found in burrows or crevices in the ground or under logs and rocks.

    The King Baboon Spider is an opportunistic predator, preying on a variety of creatures, including insects and small invertebrates. They are skilled ambush hunters, lying in wait near the entrance of their burrows to capture passing prey.

    Goliath Pinkfoot Tarantula (Avicularia juruensis)

    Avicularia juruensis Amazonian pink toe spider Avicularia juruensis
    Avicularia juruensis. Image: Zookeys.

    The Goliath Pinkfoot Tarantula is a relatively large arboreal tarantula species with a leg span that can reach up to approximately 20 cm (about 8 in). It gets its common name from the striking pinkish or reddish hairs on its feet, which stand out against its overall dark coloring.

    These tarantulas are native to South America and are particularly found in regions such as Brazil, Venezuela, and Peru. They are arboreal by nature, which means they are well adapted for living in trees and are often found in forested areas.

    The Goliath Pinkfoot Tarantula is an insectivore, preying primarily on a variety of insects, such as crickets, moths, and other arthropods. They are agile hunters, capturing prey using their silk threads as a web and ambushing them.


    This species is known for being docile and is generally not aggressive towards humans. It is often kept as a pet by tarantula enthusiasts.

    Cobalt Blue Tarantula (Haplopelma lividum)

    Cobalt Blue Tarantula (Haplopelma lividum)
    A large female Haplopelma lividum. Image: Wikimedia.

    The Cobalt Blue Tarantula is a medium-sized tarantula with a leg span that typically ranges from 13 to 15 cm (around 5 to 6 in). It is recognized for its striking cobalt blue color, which is the primary reason for its common name.

    This species is native to Southeast Asia and is particularly found in countries like Thailand, Myanmar, and Malaysia. They are often discovered in tropical rainforests, where they make burrows in the ground or utilize crevices in rocks.

    The Cobalt Blue Tarantula is an aggressive predator, feeding on a variety of prey, including insects, other arachnids, and small vertebrates. They are known for their agility and speed, effectively capturing their prey by ambushing or chasing them.

    Unlike many other tarantula species, the Cobalt Blue Tarantula is known for its highly defensive and sometimes aggressive behavior. They are not typically docile and are often characterized by a strong-willed and skittish disposition.

    The Cobalt Blue Tarantula is a highly prized species among tarantula enthusiasts due to its stunning blue coloration. However, its aggressive temperament makes it a challenging species to keep as a pet, and it is not recommended for novice tarantula keepers. In the wild, it plays a role in controlling insect and small vertebrate populations within its ecosystem.

  • How Spiders Fly: Electricity Instead of Wings

    How Spiders Fly: Electricity Instead of Wings

    Some spider species use their threads to soar through the air. They employ more than just wind and thermals to accomplish this. Additionally, even in a dull environment, the electrical field of the ground still gives them the required propulsion. Since spiders lack wings, they shouldn’t be able to fly in reality. But sometimes you witness them soaring through the air on long silk strands, dramatically dispelling this belief. Many spider species have been documented to use this flying strategy for a very long period of time.

    The Electrostatic Processes

    The “Beagle,” Darwin’s research vessel, has already had guests with eight legs. He explained how a spider entered the aircraft and left once again, “thrusting four or five threads out. They were more than 3.3 feet (1 m) long and stretched upward away from each other, starting from the gland openings. Suddenly the spider released its grip from the post and was quickly carried out of sight,” said Charles Darwin.

    Darwin reported that the day was hot and windless. He attributed the spider’s ability to fly in spite of the lull to minute thermal convection movements. In fact, the theory could help explain certain crucial facets of the phenomenon. Darwin also had a sneaking suspicion that electrostatic forces might be involved.


    The spreading of the threads that were shooting out in a fan-like pattern, seeming to oppose one another, reinforced this.

    The belief that spider flying was solely dependent on aerodynamics persisted up to the present day, despite such signs of potential charge effects. Scientifically speaking, this made sense. However, study findings that provide electrostatic processes with an additional supportive function have just been released.

    If aerodynamic lift alone is to blame for recent advancements, then difficulties that become apparent upon closer inspection are likely to have played a role. For instance, it is unknown how spiders, which can weigh up to 100 milligrams, utilize their filaments to launch themselves upwards at a startlingly high rate of speed despite the lack of any breeze. Additionally, Darwin had previously seen the spreading of the bundles of expelled threads. Additionally, species of flying spiders were discovered at an altitude of 2.5 miles (4 km), which presented a significant fluid dynamics difficulty.

    By taking into account the impacts of the Atmospheric Potential Gradient (PG), these issues may be resolved. Charge disparities between the atmosphere and the earth are involved in this. The Earth’s surface is negatively charged, whereas the ionosphere, which is more than 43 miles (70 km) above it, is mostly positively charged. The whole region between them is impacted by the disparity. As a result, the atmosphere above the ground is positively charged in comparison to it, creating an electrical potential difference between a location on the ground and a point in the atmosphere above. Up to around 100 volts per meter are possible. However, the intensity of the impact fluctuates and is strongly influenced by the weather.

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    Sensitive to Electric Fields

    Frontinellina frutetorum, the flying spider of the Linyphiidae family
    Frontinellina frutetorum, the flying spider of the Linyphiidae family.

    This is already evident from the way the spider’s strands repel one another. Additionally, silk filaments are electrically charged. As a result, they will always interact with each other and the air field, which will result in movement. But how can the spider predict if the pressures would be powerful enough to pull it along with its thread in advance?

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    It must be able to detect electric fields and assess their strength in order to achieve this. Insects’ ability to accomplish this, at least in certain cases, has been known about for a while now.

    Erica Morley and Daniel Robert from the University of Bristol investigated the effects of fields on spiders in 2018. In controlled laboratory studies, canopy spiders (Linyphiidae) were subjected to electric fields of comparable intensity to those found in the environment during various weather situations.

    Indeed, in response, the spiders made obvious preparations to take to the air. When the fields were turned on or off, the flying creatures either rose or fell.


    It follows that the electrical contact between the animals and the external fields must play a part in the ascent, in addition to the aerodynamic lift. It is thought that spiders are able to detect electric fields via the movement of specialized tactile hairs called trichobothria located on the animal’s skin.

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    The displacement of spider trichobothria via mechanical means. Erigone‘s trichobothria. (Credit: ScienceDirect)

    The air potential gradient and wind conditions have a significant impact on the lives of flying spiders. Even so, they likely have some sway. Charbel Habchi from Notre Dame University Louaize in Lebanon and Mosbeh M. Khalid Jawed from the University of California, Los Angeles published the findings of their computational modeling in a paper this year (2022). According to the findings of the two engineers, spiders may manipulate fluidic and electrostatic conditions by adjusting the quantity and length of their filaments. Therefore, the flying critters were not totally powerless.

    The mechanism by which the spinning threads are electrically charged remains unclear. Consequently, this interesting example of nature using an electric motor to power itself is likely to continue to reveal its mysteries for years to come.

  • 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.