Final answer:
Decapods, a group within crustaceans, have five pairs of walking legs and normally one pair of chelipeds. Biramous appendages are characteristic of these marine and freshwater arthropods, which is a distinguishing feature when compared to myriapods and hexapods.
Step-by-step explanation:
Decapods' Number of Legs
Decapods, a group of crustaceans, typically have five pairs of walking legs and one or two pairs of chelipeds—also known as claws or pinchers—which are specialized legs used for catching, picking up, and holding onto their food. Chelipeds vary in number, but typically there is one pair present in decapods. While myriapods such as centipedes and millipedes may have a highly variable number of legs, with centipedes like Scutigera coleoptrata having up to 15 pairs of legs and millipedes like Narceus americanus having many legs, decapods have a consistent number of ten legs (hence the prefix 'deca-' which means ten).
Crustaceans are a diverse group of arthropods and include creatures such as crabs, lobsters, and shrimps. Unlike myriapods, which have uniramous (single-branched) legs, crustaceans typically have biramous (two-branched) appendages. Their legs are an important feature in distinguishing between different classes of arthropods. Decapods differ from other arthropods like insects (hexapods) which have only three pairs of legs.