Kids Research Express

. Spiny-Headed Worm, a common name for members of a phylum of about 500 species of intestinal parasites that attach to a host by means of spines on an extensible proboscis. They lack a gut and circulatory system and absorb nutrients through the body wall. Adults have separate sexes and live in the intestines of vertebrates. Their eggs are shed with the host's feces and are eaten by invertebrates, into whose tissues the larvae burrow. When the invertebrates are eaten by vertebrates, the latter serve as new hosts. Spiny-headed worms do considerable damage to various fishes, birds, and mammals, including some domesticated animals. Scientific classification: Spiny-headed worms make up the phylum Acanthocephala.

. Kinorhyncha or Echinodera -> Tiny worms with spiny bodies. An outer protective cuticle is segmented and articulated. Found in the muddy bottoms of coastal waters, they feed on microorganisms and organic particles by means of a sucking pharynx. Reproduction is sexual. Examples: Echinoderes, Condyloderes Nematoda -> Commonly known as roundworms, these animals are one of the most diverse and geographically widespread invertebrate phyla. Free-living roundworms inhabit freshwater and marine habitats, as well as soil. Parasitic roundworms prey on both plants and animals, causing widespread agricultural damage and disease. Roundworms have long, cylindrical bodies with a mouth surrounded by lips and sensory papillae or bristles. Fluid in the body cavity distributes nutrients and oxygen—roundworms do not have special respiratory or circulatory systems. Roundworms prey on other invertebrates as well as diatoms, algae, and fungi. They reproduce sexually and larvae undergo at least four