Students of the University of Utah's Life Study Laboratory Preschool in Salt Lake City, Utah, for their question:
DO SPIDERS HAVE EARS?
Spiders live anywhere they can find food. You'll find them in caves, swamps, woods and fields. Most of them are man's friends since they eat harmful insects. Many people think spiders are insects, but they are not: They're classified as arachnids. Unlike insects, spiders do not have wings and they have eight legs instead of four.
Two main sections make up a spider's body: the cephalothorax, which is a combination of head and chest, and the abdomen. A thin waist called the pedicel connects the two sections.
A spider's complete central nervous system is located in its cephalothorax. Here you'll find the creature's brain and the controls for the rest of its body.
A spider does not have ears but it has highly developed senses. Special hairs on its body serve as organs of touch and perhaps as organs of hearing and smell. Each hair has a nerve in it. The nerves send messages to the brain that tell the spider how to react to changes in its surroundings.
A spider's most highly developed sense is his sense of touch. They can also easily sense vibrations and the presence of certain chemicals. Eyes are located on top and near the front of a spider's head. The number, position and size of the eyes vary among the different species. Most have eight eyes which are arranged in two rows of four each. Others have six, four or only two eyes. Some species of spiders that live in caves or other dark spots have no eyes at all. All spiders can see only a short distance.
Many transparent, pale blood cells make up the spider's blood. The heart is a slender tube in the abdomen, and it pumps blood to all parts of the body. The blood flows through open passages instead of closed tubes, such as those found in humans. If a spider accidentally breaks his skin, the blood will quickly drain from its body.
A digestive tube extends the length of a spider's body. Juices in the tube break the liquid food into particles small enough to pass through the walls of the intestine into the blood. The food is then distributed to all parts of the body.
A spider's mouth is an opening located below its eyes. It does not have chewing parts. A spider only consumes liquids and sucks its victim's body fluids. It can also spray a digestive juice on the victim's tissues. A large tarantula, for example, can use predigestion and sucking to reduce a mouse to a small pile of hair and bones in about 36 hours.