Fun Crab Spider Facts For Kids

Crab spiders are spiders mostly from the Thomisidae family; however, a few species of other families are also considered crab spiders. These are found all over the world in forests, meadows, gardens, and plant-covered dunes. Evidently, they get their name from their striking resemblance with crabs. They are brilliant ambush predators, i.e. they sit and wait for the prey rather than going after their prey. They produce silk webs but only for reproductive purposes. Crab spiders can change their body color at will. They have a complex system of eight eyes that enable them to look in every direction. They live on insects visiting flowers. Predators of crab spiders include wasps, ants, large spiders, and birds. Crab spiders may be fairly small to considerably large in size, and they are not harmful to humans.

If you like to know more about different arthropods, you are welcome to check out our articles on the yellow sac spider and the Brazilian wandering spider.

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What type of animal is a Crab Spider?

Crab spiders are species of spiders belonging to the Thomisidae family.

What class of animal does a Crab Spider belong to?

Crab spiders are arthropods belonging to the class Arachnida.

How many Crab Spiders are there in the world?

There are 175 genera and more than 2100 species of crab spiders all over the world.

Where does a Crab Spider live?

Crab spiders may be found in the woods, farms, gardens, agricultural lands, meadows, etc. Wherever it is, they can mostly be seen in the proximity of bright-colored flowers.

What is a Crab Spider's habitat?

Crab spiders are mainly found in common spaces like gardens, ponds, and marshes, and even areas like tropical rainforests and scrublands. The crab spider can, thus, be found in a variety of areas and ecosystems except for areas that usually have extreme temperatures. These areas include snow-clad mountains, mountain ranges, and deserts with extremely low precipitation.  The wide range of ecosystems that the crab spider can be found in is a testimony of its ability to adapt to different circumstances.

Who do Crab Spiders live with?

Crab spiders are mainly solitary in nature. They are usually known to exist and hunt alone. While the reproduction rituals dictate that they mate in pairs, this is purely an exercise in reproduction. By nature, these spiders have been known to hunt during the day, and they are proficient hunters.

How long does a Crab Spider live?

Crab spiders take 100-200 days to reach adulthood. Males live another 35-40 days after mating, if not cannibalized by their female counterparts; whereas the females usually live another year after laying their eggs.

How do they reproduce?

A day after their last molt, which takes place in May and early June, male crab spiders build webs inside their mating chamber. A female crab spider's last molt usually occurs from mid to late June. They can be ready for mating as soon as one hour afterward. To attract the females, male crab spiders vibrate their abdomen and move their first two pairs of legs along with their palpi, which is an appendage near their mouth. The male then touches her legs with his first two pairs of legs. If the female approves, she lets herself hang from the web, lifting her legs. Most species are polygynous, i.e. the males mate with multiple females. The females mate only once and they prevent more mating by shielding their genitals with a waxy covering.

Approximately 23 days after mating, the female lays eggs in a large sac made by her with a white sheet of the web. Two such egg sacs are formed, each containing about 145 eggs covered in silk. The incubation period of the eggs is up to 11 days. 23 days after the eggs are laid, baby spiders leave their sacs and enter the second phase of development, known as an instar. Males reach adulthood after four or five instars, whereas females take six or seven instars to mature. Female Japanese crab spiders can lay up to 1.5 million eggs every year.

What is their conservation status?

There are many species having different conservation statuses. Some of them are:

Misumena nigromaculata: Data Deficient

Xysticus grohi: Critically Endangered

Philodromus signatus: Of Least Concern

What do Crab Spiders look like?

Crab spiders have a short, wide, and flat body that looks similar to a crab. They have eight pairs of legs, of which the front two pairs are the largest and strongest. They use these to grab their prey. Their front legs are held out and they can walk sideways and backward, just like crabs. So it is quite evident how they get their name. The females are twice as large as the males; in some species, they may be even 60 times larger than males. They have eight eyes that serve as an added advantage to observe the movements of their prey, and also the predators of crab spiders. Different species of crab spiders have different colors like yellow, green, white, brown, etc. Some species show sexual dimorphism in color besides the size. One thing is common in diversity, that is, most of them can change color. They are very good at camouflaging with their surroundings. There are even some species that, on consuming colorful prey, can turn their body into the color of their prey.

How cute are they?

Like all other spiders, crab spiders also cannot be considered cute. In fact, they are quite scary; perhaps scarier than other spiders because of their crab-like appearance. However, some people have been known to keep spiders as pets, and therefore some people might find spiders cute.

How do they communicate?

Crab spiders usually prefer to be own their own. During mating, the male shows interest by stroking the front legs of the females. In some species, males follow silk threads to reach females. Their visual perception is very high because of their eight eyes. They also use chemicals to identify their hunting spot.

How big is a Crab Spider?

Females are about 0.24–0.35 in (0.6–0.9 cm) long; males are approximately 0.12-0.16 in (0.3-0.4 cm).  

How fast can Crab Spiders move?

Crab spiders usually walk sideways with their hind legs, but there are some species that move like other spiders. Crab spiders have generally been known to be extremely quick on their feet.

How much does a Crab Spider weigh?

Crab spiders weigh 0.00099 oz (0.03 g) on average.

What are their male and female names of the species?

The male and the female members of the crab spider do not have any specific names.

What would you call a baby Crab Spider?

A baby crab spider can be called a spiderling, like the baby spiders of all other species.

What do they eat?

Crab spiders prey on insects like honeybees, flies, butterflies, moths, and more, who come to feed on the nectar of flowers. They are ambush predators, which means they prefer to sit and wait for the prey over moving around and chasing them. Their success depends on reactions rather than speed. Most crab spiders can change color and camouflage with the flower on which they sit. When the insects come to the flowers, crab spiders use their front legs to abruptly grab them from an apparently still position.

Are they harmful?

Crab spiders are usually beneficial to humans as they prey on insects and pests. They are not venomous enough to harm large animals, and they cannot bite humans.

Would they make a good pet?

Crab spiders are solitary in nature and they do not like to stay inside. Attempting to pet them, like any other spiders, does not sound like a good idea.

Did You Know...

These arachnids play an important role in the ecosystem by preying on crop pests and controlling their population.

They use their silk thread to tie several flower petals to form structures called 'bowers'. This is their sitting place while they watch out for their prey.

Tropical crab spiders have a longer lifespan than other species.

Crab Spider Bite

Crab spiders are venomous, but their mouth apparatus is too small to penetrate human skin. Even the giant crab spider, which is big enough to bite humans, cannot cause any considerable or long-lasting harm except mild pain.  

Variations of Crab Spider

There are 175 genera and 2,100 species of crab spiders. Naturally, they can be of many types some of which are giant crab spiders or huntsman spiders, goldenrod crab spiders or flower spiders, swift crab spiders, and more. The majority of the crab spiders belong to the family Thomisidae; however, there are members of some other families like Sparassidae (giant crab spiders), Selenopidae (wall crab spiders), Sicariidae (six-eyed crab spiders) who also are included in crab spiders.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other arthropods including the six-eyed sand spider and the wolf spider.

You can even occupy yourself at home by drawing one of our Crab spider coloring pages.