Natural Enemies & Defence

Of all the billions of spiders that are born every day on Earth, more than 99% of them die before reaching adulthood. They are preyed upon by other spiders, a range of insects, scorpions, centipedes, fish, frogs, reptiles, birds and mammals. They also suffer from diseases and are attacked by fungi and parasitic worms.

THE WORM TURNS

One of the most bizarre groups of creatures to attack spiders are Gordian Worms.

These worms are long and thin and live in freshwater, where they lay thousands of eggs. The newly hatched worms may be eaten by fresh water insect larvae with eventually mature with the dormant worms inside and leave the water. The insects is then eaten by the spider, after which the worm breaks its dormancy, burrows out through the spider's stomach and feeds on its internal organs. When the spider eventually dies, the worm emerges from the dead body and makes its way back to the water.

FLY EATS SPIDER

Many types of parasitic insects, particularly flies and wasps, also attack spiders. These parasites, technically called "parasitoids" because they eventually kill their hosts, may attack the eggs, spiderlings or adult spiders.

An Ichneumon Wasp, for example, will lay an egg on the outside of a spider and, when the egg hatches, the tiny larva burrows into the skin and feeds on its host's internal organs. The spider continues to feed and behave naturally, until the burden of the parasite overwhelms it. Spider-Hunting Wasps use the same strategy but instead of leaving the spider in place, the wasp paralyses the host and carries it back to the nest. An egg is laid on the spider and it is sealed up either in the burrow or in the nest made from dry mud.

THE BEST DEFENCE

A spider's most effective strategy in defence of all attacks is to hide. Most spiders are active nocturnally, avoiding birds and most of the parasitic wasps and flies. During the day they hide under bark or underground, or camouflage themselves so superbly they are almost impossible to see.