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.
Segmented worms (Annelida) are a group of invertebrates that includes about 12,000 species of earthworms, ragworms and leeches. Segmented worms live in marine habitats such as the intertidal zone and near hydrothermal vents.egmented worms are classified within the following taxonomic hierarchy: Animals Invertebrates. Segmented worms are divided into the following taxonomic groups: 1  Polychates-The polychaetes include about 12,000 species that are characterized by having multiple hairs on each segment.