Sit-and-wait predators | Crab spiders: Camouflage, attack, savour

A crab spider waiting to ambush an ant. Photo by Author

Crab spider capturing a fly larger than its body size. Photo by Author

Crab spider feeding on a catterpillar. Photo by Author

An ant mimicking crab spider with its prey. Photo by Author

Female crab spider. Photo by Author

Female crab spider. Photo by Author

Crab spider changes its body colour to match that of the flower. Photo by Author

A male crab spider. Photo by Author

Bees and flies visit several flowers to collect nectar. While the sight of bees hovering over flowers is beautiful, were you aware that danger could be lurking just around the corner?

Once I spotted a bee sitting on a flower, but as time passed the bee didn't fly or move and that caught my attention. On closer observation, I realised that bee had been a victim of an ambush of a well-camouflaged crab spider.

What sets them apart?

Crab spiders are found in a variety of environment. Wherever they are present, they quietly control the population of other insects.

There are a variety of spiders that live in our gardens. Most of them roam around in search of other prey insects. But there are some species which are not active hunters; one such type is the crab spider.

Crab spider gets its name from crabs, as it not only resembles a crab, but also has the ability to walk backward and sideways, just like a crab. Crab spiders can be found in a variety of habitats except in the extremely dry and cold conditions. They come in a variety of body size and shapes; they resemble other free-living spiders such as the wolf spiders and jumping spiders.

The body is short, wide and flattened. The first two pairs of legs are longer compared to the rest of the legs. The crab spiders have eight small eyes serving primarily as motion detectors.

One can find the crab spiders on grass, bark, leaf and flowers. Depending on the place they live they show an interesting array of adaptation for their survival. Crab spiders lie and wait to ambush their prey. Their jaws are rather small and slender, possessing fang-like mouthparts and venom that is strong enough to immobilise the prey. Crab spiders hunt and eat insects that visit flowers to feed on nectar. Honeybees, butterflies and flies are their favourite foods.

Like all other spiders, crab spiders can produce silk, but they do not build web, instead use their ability to camouflage to capture prey.

These crab spiders hide in flowers and can change colour to match their hunting terrains, including flowering plants and sometimes leaves, while others merge with the backgrounds. Female spiders can be white, yellow, or pale green; males are darker and typically patterned. Some crab spiders change their body colour over many days, ranging between white and yellow, depending on the colour of the flower on which they are waiting for the prey. Crab spider can also mimic insects.

These spiders rest on flowers and stay motionless for long periods with the first two pairs of long legs wide open in readiness to ambush the prey that visits the flower for nectar and pollen. The venom of these spiders enable them to successfully attack larger prey than themselves. Like other spiders, crab spiders do not spin web nor wrap their prey in silk after biting, but instead, stay still with the paralysed prey until it has sucked the prey dry.