Crab Spider: The Amazing Arachnid That Can Change Colour

Crab spiders are fascinating creatures that have captured the attention of nature enthusiasts around the world. Their distinctive appearance, with long legs bent at a sharp angle, gives them their name, as they look like miniature crabs. These tiny spiders can be found in various habitats, including forests, fields, and gardens, making them a common sight in nature. 

If you’re curious about their biology, behaviours, and environmental roles, this article is just the thing for you! You’ll find plenty of information that will help you understand more about these intriguing spiders, even if you’re one of the many people who suffer from arachnophobia.

Physical Characteristics of Crab Spiders

Body Shape and Size:

They exhibit a size range of 0.1 to 1 inch, boasting a compact and flat physique, setting them apart as relatively diminutive in comparison to other spider species.

Chelicerae:

Impressively, They possess formidable chelicerae, or jaws, which serve as their primary tool for capturing and gripping prey.

Eyes:

At the forefront of their heads, they showcase eight sizable eyes, granting them exceptional vision that aids in locating prey and navigating their surroundings.

Legs:

Endowed with elongated and robust legs adorned with spikes, crab and possess the ability to cling onto their prey and scale various surfaces. This feature also contributes to their adeptness at blending in with their environment, facilitating effective camouflage.

Coloration:

Exhibiting an array of colors, such as white, yellow, brown, green, and black, by which they effortlessly blend into their specific habitats, staying concealed from both predators and prey.

In conclusion, the combination of their flat body shape, prominent chelicerae, keen vision, and spiny legs collectively empowers crab spiders as skillful hunters while simultaneously aiding them in evading potential threats.

Types

#1 Flower Crab Spider (Misumena vatia)

Flower Crab Spiders, scientifically known as Misumena vatia, are a fascinating spider species found in diverse regions around the globe. They exhibit a distinct lifestyle, dwelling on flowers and employing an ambush-hunting strategy to capture their prey.

These spiders are typically small to medium-sized and boast long, slender legs. Their flat bodies serve as a clever adaptation, enabling them to seamlessly blend into their surroundings, thus confounding potential predators. With a variety of colors in their repertoire, such as white, yellow, green, and brown, Flower Crab Spiders masterfully camouflage themselves amidst the flowers, which serve as their primary hunting grounds.

Their preferred habitats encompass gardens, meadows, and woodlands, where they actively prey on small insects like flies, bees, and butterflies. Employing the ambush hunting technique, they patiently lie in wait for their unsuspecting prey to draw near, then swiftly strike using their powerful legs. This, combined with their ability to change colour to match their environment, renders them even more proficient hunters.

Beyond their intriguing hunting habits, Flower Crab Spiders play a vital ecological role in controlling the populations of small insects and other spiders within their ecosystems. Whether one holds a fascination for spiders or simply possesses an interest in the wonders of the natural world, these unique creatures are undoubtedly worth exploring further.

#2 Running Crab Spider (Philodromidae)

The Running Crab Spider, scientifically known as Philodromidae, is a species of spider found in various regions across the world, including North America, Europe, and Asia. Renowned for their remarkable agility and swift movements, these spiders are intriguing creatures to observe.

Typically, Running Crab Spiders are of small to medium size, measuring between 0.2 to 0.6 inches in body length. They possess flattened bodies with elongated, slender legs, giving them a distinct crab-like appearance that contributes to their name. The spiders display a range of colours such as brown, grey, and white, with certain species showcasing markings on their abdomen.

Their preferred habitats encompass grasslands, gardens, and woodlands, where they actively hunt for small insects and other spiders. Employing their quick movements, they scurry across leaves and stems to catch their prey, which primarily consists of small insects like flies, ants, and bees.

The Running Crab Spider is particularly notable for its agility and rapid motions, which enable it to swiftly pursue its prey. Its ability to move in various directions, including backward, adds to its elusive nature, making it challenging to apprehend. Additionally, the spider possesses the capability to change colour, effectively blending into its surroundings, further enhancing its proficiency in capturing prey.

As with all spiders, the Running Crab Spider plays a crucial role within its ecosystem by aiding in the control of populations of small insects and other spiders, thus contributing to the delicate balance of the natural world.

#3 Green Crab Spider (Misumessus oblongus)

The green crab spider, a small but fascinating creature, is perhaps best known for its striking green colour, which it uses to blend seamlessly into the foliage around it. But there’s more to this spider than meets the eye. Dubbed an “ambush predator,” the green crab spider is a patient hunter, waiting stealthily until small insects or other spiders come within striking distance. But perhaps even more impressive is the spider’s ability to change colour, adapting to its environment in order to become an even more effective hunter. 

Habitat of Crab Spiders

Crab spiders exhibit a wide global distribution, being adaptable to various habitats around the world. They can be found in forests, fields, gardens, and even urban areas, showcasing their versatility.

One of the key preferences of crab spiders is their inclination towards environments that offer ample cover, such as leaves and flowers. This attribute allows them to stay in the same location for extended periods, as they blend seamlessly with their surroundings, effectively avoiding both prey and predators.

In forest environments, crab spiders can be encountered either on the ground or within trees and shrubs. Utilizing their long legs, they adeptly climb and position themselves on leaves, where they lie in ambush, waiting for passing insects to prey upon.

Similarly, in fields and gardens, crab spiders are commonly found. They skillfully employ vegetation as a hiding spot, enabling them to remain concealed from both potential prey and predators. Often, they perch on flowers, patiently awaiting the opportunity to ambush insects that pass by.

Remarkably, crab spiders have also adapted to urban environments. Within cities, they exploit man-made structures to conceal themselves from both prey and predators. Observing them on buildings, walls, and gardens is not uncommon, as they cleverly utilize the surrounding vegetation as additional cover.

Overall, the ability of crab spiders to adapt to diverse habitats and effectively utilise cover for hunting and protection has contributed to their success and wide distribution across the globe.

Diet and Feeding Habits of the Crab Spider

Role In Ecosystems

Indeed, crab spiders hold a vital ecological role within the ecosystems they inhabit, particularly in maintaining the balance of insect populations.

Predation on Pest Species:

One of the significant contributions of crab spiders to their environment is their role as important predators. They actively prey upon various insects that are often considered pests, such as aphids, flies, and mosquitoes. By feeding on these pest species, crab spiders help to regulate their populations and curb potential damage they could cause to crops and gardens. This natural pest control service aids in promoting the health of plants and agricultural productivity.

Role in Pollination:

In addition to their predation activities, crab spiders also play a noteworthy role in pollination. While they are engaged in hunting on flowers, they frequently come into contact with the plant’s reproductive structures, inadvertently picking up pollen. As they move from one flower to another, they can transfer this pollen, contributing to the pollination process. Pollination is crucial for the reproduction and survival of many plant species, and the involvement of crab spiders in this process helps to ensure the continuation of diverse plant populations.

Mating Habits of the Crab Spider

Crab spiders are known for their unique mating and reproductive behaviors. The timing of their mating season occurs during the spring and early summer months. Once the male and female crab spiders mate, the female will lay her eggs in a silk sac. Unlike other spider species, females of the crab spider will take on the responsibility of guarding and feeding their offspring. The female crab spider will protect her eggs and young from predators, while also feeding them with insects that come near. It is important to note that the male crab spider will often die after mating, leaving the female to care for her young on her own. 

Social Behaviors of the Crab Spider

Crab spiders exhibit a solitary nature, preferring to lead individual lives and not forming social groups. Instead, they establish and defend their own hunting grounds, displaying a territorial behaviour.

When it comes to encounters with other spiders, crab spiders do not actively seek out confrontations. They are not aggressive in their interactions and tend to avoid unnecessary conflicts. However, they are keenly aware of other spiders that pose a potential threat to their territory. In such instances, crab spiders will take defensive actions to protect their hunting ground from intruders.

The ability of crab spiders to distinguish between other spiders that are potential threats and those that are not helps maintain a balance in the ecosystem. By defending their territory, they prevent overcrowding and competition for food and resources. This territorial behaviour contributes to a more sustainable environment where each spider can efficiently hunt and thrive within its own designated area.

Adaptations and Survival Strategies

Camouflage and Mimicry:

Crab spiders are remarkable masters of camouflage, and certain species take their deception skills to the next level by mimicking other insects, such as ants and bees. This clever adaptation allows them to blend seamlessly into their surroundings, making it difficult for predators to detect them. By imitating other harmless insects, crab spiders can evade potential threats and increase their chances of successful hunting.

Venom and Defense:

Crab spiders employ venom as a means to immobilise their prey during hunting. The venom is not typically harmful to humans and rarely poses serious risks. A bite from a crab spider is usually not painful or dangerous, but it may cause skin irritation and mild swelling in some cases. Although severe reactions to crab spider bites are uncommon, if an individual experiences an unusually strong reaction, such as severe pain, difficulty breathing, or other alarming symptoms, immediate medical attention should be sought.

Overall, crab spiders’ ability to utilise camouflage and mimicry showcases their remarkable adaptability and defensive strategies in the natural world. While their venom serves as an effective tool for subduing prey, it is generally harmless to humans, reinforcing their status as fascinating and relatively harmless creatures within their ecosystems.

Are Crab Spiders harmful?

Spider crabs are fascinating creatures that go by different names like crab spiders or decorative crabs. They are not known to pose any danger to humans as their venom is usually not strong enough to cause any harm. However, it is important to note that some crab spiders may bite when they feel threatened, so it’s best to avoid touching them altogether. It’s better to err on the side of caution and seek medical help if you feel unwell or experience any allergic reactions after coming into contact with these creatures. Despite their benign nature, it’s always important to treat spider crabs with respect and give them their own space.

The Future of Crab Spiders

Indeed, the future of crab spiders, like many other species, is subject to various factors, and while specific predictions are challenging, some trends can impact their populations.

Climate change poses a significant concern for crab spiders. Alterations in temperature and precipitation patterns may disrupt their habitats, affecting both the availability of prey and the vegetation that provides essential cover. Some species may struggle to adapt, leading to population declines, while others might find opportunities to thrive under the changing conditions.

The increasing use of pesticides in agriculture and other land-use practices is another potential threat to crab spiders. Pesticides can harm not only the target pests but also non-target species, including insects that serve as important prey for crab spiders. If pesticide usage continues to rise without adequate conservation measures, it could result in detrimental consequences for crab spider populations.

However, there is hope for the conservation of crab spiders and their habitats. Growing awareness of biodiversity’s significance and the importance of maintaining ecosystem health can drive efforts to preserve and restore suitable habitats for these spiders. Conservation initiatives may aim to protect natural areas and implement sustainable land-use practices that minimise harm to crab spider populations.

As with all species, the future of crab spiders is intricately linked to the broader environmental context and the actions taken by humans to safeguard their habitats. By understanding and addressing the potential challenges, there is an opportunity to promote the conservation of these diverse and fascinating arachnids and contribute to the overall health and balance of our ecosystems.

Key Points

• Crab spiders, including Running Crab Spiders, showcase a size range of 0.1 to 1 inch in length, presenting a relatively small stature when compared to other spider species. Running Crab Spiders themselves fall within the small to medium-sized category, measuring between 0.2 to 0.6 inches in body length.
• Their distinctive appearance features flattened bodies adorned with long, slender legs, earning them the name “crab spiders” due to their resemblance to crabs.
• As ambush predators, these spiders exhibit a patient hunting technique. They lie in wait, hidden and low, until their prey, which primarily comprises small insects and other spiders, comes within striking distance.
• To immobilise their prey, crab spiders utilise venom, which, fortunately, poses no significant harm to humans. A bite from a crab spider is typically not painful or dangerous, although it may cause mild skin irritation and swelling.
• A remarkable aspect of Running Crab Spiders is their agility and rapid movements. They are capable of manoeuvring in any direction, including backward, rendering them elusive and challenging for predators or potential captors to catch.
• Overall, the combination of their small size, flattened bodies, ambush hunting strategy, and non-harmful venom makes crab spiders, including Running Crab Spiders, fascinating and well-adapted creatures in the natural world. Their quick movements and elusive nature only add to their allure as intriguing arachnids.

FAQs

Is the spider crab poisonous?

The truth is that the spider crab is not venomous or poisonous to humans. However, it is important to handle these creatures with care as they can have sharp claws that can potentially harm a person. 

Why is it called a crab spider?

These spiders have two pairs of legs that are significantly longer than their other two pairs, giving them the appearance of crab claws. They also have the ability to scuttle sideways, just like crabs. 

What are the abilities of a crab spider?

These spiders have the remarkable ability to change their color to blend in with their surroundings, making them excellent hunters. While most spiders spin webs to catch their prey, crab spiders rely on their agility and stealth to pounce on unsuspecting victims. They are also equipped with strong jaws that can crush their prey quickly. 

Final Words

These spiders have a unique appearance that makes them stand out among other arachnids and insects. Their bodies have a flattened, crab-like shape, and they can change colours to blend in with their surroundings. Crab spiders are also incredibly effective predators, using ambush and stalking strategies to capture their prey. They play an important role in maintaining the balance of the food chain, preying on insects that would otherwise overpopulate and harm other species. 

Reference:

• https://uwm.edu/field-station/crabspiders/ 
• https://en.wikipedia.org/wiki/Misumena_vatia 
• https://www.seafoodcornwall.org.uk/the-ultimate-guide-to-killing-a-spider-crab-humanely/