Question

You learned that members of this class were formerly divided into two groups: Errantia and Sedentaria.

Answer 1

Polychaetes

Explanation:

• Polychaetes is any of the diverse, mostly marine segmented worms of the annelid class Polychaeta, characterized by having most segments with one pair of lateral, fleshy, lobe like appendages called parapodia, with numerous bristles projecting from them
• Polychaetes have true segments and anterior to the true segments lie the prostomium and peristomium
• This head region of two segments typically contains two pairs of eyes, three antennae, several tentacles, a pair of palps, and the mouth
• Polychaeta is divided into Errantia and Sedentaria for convenience
• Errantia (scaleworms, sea mice):A subclass of polychaete worms which have a large number of body segments, those of the head and posterior differing from the rest,the mouth often has several paired jaws
• Most are vagile predators, others adopt a burrowing mode of life and are first recorded from the Cambrian
• Sedentaria (bamboo worms, coneworms):A subclass of entirely marine worms in which the body segments and parapodia differ along the length of an individual,all Sedentaria are burrowers or tube-dwellers and are first recorded from the Ordovician