Phylum Arthropoda Essay

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Phylum Arthropoda The largest phylum of Earth is Arthropoda. Included in this phylum are insects. Insects have been a very successful class within the phylum. There are several biological characteristics that have contributed to the success of insects. Insects have been around for more than 400 million years. They have survived at least 4 major catastrophes that resulted in planet-wide extinctions and yet they still thrive no matter our efforts to get rid of them all! There is no one single characteristic that links to their success but they do have a combination of unique characteristics that together give insects a big advantage when it comes to survival. Insects have an exoskeleton, they are small, they have the ability to fly, they reproduce frequently and in high numbers, they complete metamorphosis and their amazing adaptability in an always changing environment all contribute to the success of insects. Insects do not have vertebrates but instead have an exoskeleton which is actually outside of their bodies and is made up of chitin which can be flexible or hard. This exoskeleton gives insects their structure but more importantly it provides protection from attack or injury. The exoskeleton can resist both chemical and physical attacks. It has an impermeable layer of wax that prevents dehydration. Since insects have an exoskeleton, small size is very important and is a distinct advantage. If insects were the size of horses and elephants, their exoskeleton would have to be proportionately thicker in order to support the large mass of body tissue. With such a thicker exoskeleton it would make it difficult for insects to even move, let alone survive! Beyond a certain size, the insect’s surface area is just too small for attachment of all the additional muscle tissue. This is why we do not see giant insects today! Also, being small means insects need very little

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