Broader definitions of chemicals or chemical substances can be found, for example: the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including â (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature.
The major groups of worms include various species of flatworm, annelid, ribbon worm, spiny-headed worm, and aschelminth. Worms typically have an elongated, tubelike body, usually rather cylindrical, flattened, or leaflike in shape and often without appendages.
Worm Classification. Worms are in a very broad category that is not officially classified in any scientific sense. While most worms are limbless invertebrates, some worms are actually reptiles or amphibians.Many other animals called worms are simply insect larvae that have yet to metamorphose into their adult stage. Nematoda â This phylum of worms includes roundworms, hookworms and threadworms. 2  Many roundworms are parasites and can cause a variety of problems for people and pets. 3  Threadworms live on the ground in damp soil, mossy areas or in decaying vegetation. 4  They can also be found in freshwater and saltwater.