Spiders

Spiders

  The spiders are arachnids that live on every continent except for Antarctica. Their fossils go back 300 million years. Spiders have eight legs and eight eyes. Their fangs inject venom to kill or paralyze their victims. Spider cannot eat solid food. They turned their food into a liquid by flooding it with digestive enzymes. Only a few dangerous spiders like the black widow use venom powerful enough kill humans. As predators they mostly eat other small invertebrates with the exception of the largest spiders. Tarantulas for example will prey on mice, lizards, and birds.

  Spiders have spinnerets that extrude silk from their abdomen but not all spiders use their silk to make webs with. Different spider species use different strategies to capture their prey. Many use sticky webs to trap their small animals with. Some are ambush predators using a trap door burrow. Others have two large eyes they use as active hunters during the day.

  Their bodies have two parts, the head and a large abdomen separated by a small flexible cylinder. The empty spaces of a spider’s body are completely filled with blood and they walk using hydraulic pressure not muscles tissue. They feel vibrations with tiny hairs on their legs like other arachnids. Spiders do not have antennae like the insects.