Phylum - Nematoda (Roundworms)
Commonly known as round worms, they are one of the most abundant types of animal on earth. Many Nematodes are free-living species, while others are parasitic on animals and plants. They are typically tapered at both ends with bilaterally symmetry. Round worms have a complete digestive tract containing a mouth with lips, a gut and anus. The body of most nematodes are made of a non-cellular cuticle. They have a nervous system that is simple. Nematodes live in most parts of the world.