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Arthropods
The largest phylum of creatures on Earth without a doubt is Arthropoda. They habitate almostly in all corners of our planet. The most common features of arthopods are bilateral symmetrical body, divided into sections, chitinous cover, articulated limbs, complex head with oral organs, striated musculature, well developed nervous system and sensory organs, unclosed circulatory system. Articular limbs perform a locomotor role.Arthopods eat different food from decomposing organic materials to the tissues of other animals and plants.
Strong claws and jaws can tear and cut coarse materials, while the stitching mouthpiece is used to suck liquids. Many aquatic crustaceans have pinnate formations on the legs or around the mouthpiece that serve to filter or filter small organisms and organic particles from the water. Most arthropods use saliva to wet food when it enters the digestive system. Three main zoologies which study 3 classes of arthropods: insects, spider-like, crustaceans, are arachnology, entomology, carcinology.