Nitric oxide (NO) Nitric oxide (NO), colourless, toxic gas that is formed by the oxidation of nitrogen. Though it has few industrial applications, nitric oxide performs important chemical signaling functions in humans and other animals and has various applications in medicine.
or British mollusc /ËmÉËlÉsk/. plural mollusks. Learner's definition of MOLLUSK. [count] biology. : any one of a large group of animals (such as snails and clams) that have a soft body without a backbone and that usually live in a shell.
Mollusks are members of the phylum mollusca. Mollusks have been evolving in the sea for over 600 million years and there are more than 100 000 mollusks species. The mollusks phylum includes tiny snails, squid, octopus, clams, oysters, abalone, and cuttlefish.They are considered to be the most intelligent of the invertabrate species.he study of mollusks is called malacology. There are four main classes in the phylum mollusca, gastropods, bivalve, cephalopod and Polyplacophora. Gastropods include nudibranches, slugs and snails. They compose over one third of the mollusk group and most are single spiral shells but some have no shells.