All though it may be hard to see, there is indeed multicellular life in this picture. Try to notice that little black dot, that seems to be floatingin mid air. That dot is no smudge on the camera, but it is a spider. How is it floating, you ask. Well it is actually walking around on it’s transparent web that is used to trap bugs. But that web isn’t the topic of this post. This post is about the spider, actually what is outside the spider. As a human we use a skeletal system and a muscular system to remain shape and move. A spider also has a skeltal system and a muscular system. The oly difference is they have an exoskeleton on the outside, where as we have a skeleton on the inside. This exoskeleton is made of many proteins and the polysaccharide chitin. Interestingly enough chitin is also used for cell walls of fungi. What aare the advantages of having an exoskeleton, you might ask. An exoskeleton is very helpful in protecting the spider from drying out. Remember that all animal life needs water, and if the animal dries out it can quite possibly die. This is an evolutionary breakthrough, to protect against dehydration, but with natural selection there is always a down side. An exoskeleton cannot grow, and it doesn’t let the spider grow, so if the spider wants to grow bigger, and spin bigger webs, it must shed the mantle in aprocess called molting. This occurs by the spider shedding the exoskeleton, securing itself from predators, growing, and then producing a new exoskeleton.