Spiders Essay, Research Paper
Spiders are very unique animals that are a common species of arthropods. They have eight walking legs, appendages that carry and inject poison, and a second pair of appendages that for males contains specialized reproductive organs. Most spiders live on land but a few species live underwater by trapping air in bubbles and by taking the bubble with them underwater. Most spiders are no bigger that one centimeter in length but the biggest has a body that is nine centimeters long.
The spider’s body is divided into two regions called the cephalothorax and the abdomen. The cephalothorax is found at the head-end of the body while the abdomen forms the rest of the body. These two parts do not go directly together but a pedicel, which is a narrow stalk that provides flexibility separates them. Every spider has two pairs of appendages with one pair containing two chelicerae and the other containing two pedipalpi. The chelicerae are used as pincers to capture food and are used to inject the poison that a spider produces into the spider’s prey. The chelicerae have fangs connected to a poison gland that holds the spider’s poison. The pedipalpi are used to feel around and sense things and in male spiders have a palpal organ used in reproduction. The abdomen contains the spinnerets that spin the silk into thread so it can be used to make webs allowing the spider to capture food. Although some spiders that are larger do not need webs because they hunt for their own food. The abdomen also contains the respiratory openings which spiders use to breathe by taking air into the book lungs. To eat their food, spiders secrete a digestive enzyme that liquefies the internal organs of a spider’s prey. After liquefying the internal organs of the prey, the spider sucks out all of the fluid from inside the prey’s body. Spiders feed on other animals and usually go about it by biting their prey and injecting poison into it. Most spiders cannot capture anything bigger than themselves but if other animals attack them, the spiders use their poison as a defense mechanism. Only a few spiders in the world are harmful to humans and in North America, the black widow and brown recluse are the only two people have to worry about.
All spiders spin silk and use it in a variety of ways. The most common use of this silk is to make webs used to capture prey like insects. A spider’s silk is much stronger than steel and its ability to stretch prevents the web from breaking easily. Some spiders use their silk to line burrows underground and baby spiders use silk as a parachute and float away after they are born.
Spiders are very beneficial to humans because most eat insects and other small animals that humans consider as pests. Most humans do not like spiders because they hide in dark places and most spiders are not appealing to a human’s eye. Some people also do not like them because a few species of spiders can be harmful but very few can kill or harm humans.
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3. http://www.ag.ohio-state.edu/ ohioline/hyg-fact/2000/2060.html