How do polychaetes differ from other annelids?

How do polychaetes differ from other annelids?

Polychaetes differ from other annelids in having a well differentiated head with specialized sense organs and no clitellum. They have many setae, usually arranged in bundles on the parapodia. The head bears eyes, antennae, and sensory palps.

Why are earthworms classified as Oligochaeta?

The ‘Oligo’ in Oligochaeta means ‘few’ just as the ‘Poly’ in Polychaeta means ‘many’. Thus the Oligochaeta are the animals with few chaetae, or few bristles. Normally, as in the common earthworms, Oligochaetes have 8 small chaetae per body segment. These are usually arranged in four groups of two around the body.

What’s the function of the Acicula in polychaetes?

Acicula (singular: aciculum) are strong, stout internal chaetae that provide support to parapodia in polychaete annelids.

What is the class of Annelida?

Most authors accept the annelids as having three major classes: Polychaeta, Oligochaeta, and Hirudinea. Older systems would place the polychaetes and oligochaetes under the class Chaetopoda because both groups possess setae.

What are the major characteristics of polychaetes?

Most have well developed, paired, paddle-like appendages (parapodia), well developed sense organs, and numerous setae (usually on the parapodia; “polychaete” means “many hairs”). Polychaetes usually have a well-developed head, often complete with well-developed eyes, antennae, and sensory palps.

How do polychaetes differ from polychaetes?

The main difference between polychaetes and oligochaetes is that the polychaetes have a pair of parapodia per body segment that bear many bristles. But, oligochaetes have few bristles on their outer surface of the body but, no parapodia.

What are examples of Oligochaeta?

Earthworms/Lower classifications

What are characteristics of Oligochaeta?

Oligochaetes, which range in length from a few millimetres (a fraction of an inch) to more than 3 m (10 feet), are notable for the absence of a head and parapodia, the flat, lobelike outgrowths used by many polychaete annelids (class Polychaeta) for locomotion. They have few setae, or bristles, on the body.

What are parapodia used for?

Parapodia are primarily the organs of locomotion used both in creeping and in swimming. Since they are highly vascularised, they also serve the function of respiration.

What is the meaning of Notopodia?

Definition of notopodium : the dorsal lobe or branch of a parapodium.