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.
The Giant Tube Worm (Riftia pachyptila) is a very unique species adapted to survive in one of Earth's most extreme and inhospitable environments. Its evolutionary adaptions in the face of such adversity include some not seen in any other organism on Earth, adaptions thought to be impossible prior to the worm's discovery in 1977.