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What is the name of the larval stage of polychaetes?

What is the name of the larval stage of polychaetes?

The Larva of planktonic Annelids are known as trocophore, which are translucent, motile zooplankton characteristic of the class Polychaeta, as well as most Mollusk species.

How do you identify polychaetes?

The polychaetes are segmented worms (Phylum Annelida), as are earthworms (Oligochaeta). The polychaetes can be distinguished by having paired, lateral appendages, parapodia, on each segment. The parapodia are usually divided into dorsal notopodia and ventral neuropodia.

Which group do the polychaetes belong to?

Polychaetes are multi-segmented worms living in all environments in the world’s oceans, present from abyssal depths to shallow estuaries and rocky shores, and even free swimming in open water. They are strictly aquatic annelids, but are the most abundant and diverse group of Phylum Annelida.

Do carnivorous polychaetes have Eversible pharynx?

External Anatomy. The head of a polychaete is composed of the prostomium, peristomium, and pharynx. The pharynx, which is mostly eversible, is the anterior part of digestive tract for feeding and is sometimes used for burrowing.

Do polychaetes have setae?

Polychaetes include such forms as sand worms, tube worms, and clam worms. Most have well developed, paired, paddle-like appendages (parapodia), well developed sense organs, and numerous setae (usually on the parapodia; “polychaete” means “many hairs”).

How do polychaetes move?

Locomotion in free-moving polychaetes is accomplished by circular, longitudinal, and parapodial muscles and by coelomic fluid. When a worm such as Nereis moves slowly, the contractual force comes from the sweeping movement of the parapodia.

What are parapodia used for?

Parapodia are paired, unjointed lateral appendages found in polychaete worms, which are often fleshy (especially in marine polychaetes) and used for locomotion, respiration, and other functions.

What do the polychaetes use to move?

‘Polychaeta’ means ‘many bristles’. And indeed, they have lots of bristles. These bristly appendages are sometimes used to move (much like a centipede does) and to burrow. In tubeworms, the appendages help grip the tube walls and to move up and down the tubes.

Are polychaetes Acoelomate?

Acoelomate bilaterally symmetrical worms, strongly dorso-ventrally flattened. Mouth ventral, gut sack-like, anus absent. Often brightly coloured in life, tropical species spectacularly so. Free living, commensal and parasitic forms.

Do polychaetes bite?

Bristleworm Sting Overview Although bristleworms are not aggressive, they bite when handled, and the bristles can penetrate skin (sting). Bristleworms are often found under rocks and corals in tropical areas throughout the world – but it’s likelier they are in your saltwater aquarium at home.

What happens if you touch a fireworm?

Fireworms produce a stinging sensation if touched. The body of H. carunculata, found in the coral reefs of the Caribbean Sea, is covered with fine, white, brittle bristles that break if touched; they easily become imbedded in human skin and produce a substance that is highly irritating.

Where does a Polychaeta live in the sea?

Polychaetes may move around at the surface of the substrate on which they live, but even the most active species are usually cryptic, nestling in cracks and crevices, under the cover of sea weed or debris or along the edge of rocks where these meet sand or mud.

Which is the most important feature of a polychaete?

A key morphological feature and at the same time one of the most important taxonomic characters of the polychaetes is the setal (chaetal) construction. The setae are ectodermal derivatives, formed by ectodermal cells that during the development have migrated to a position well below the rest of the ectodermally derived epidermis.

How are polychaete worms separated into two orders?

Polychaetes traditionally are separated into two large orders, ERRANTIA and SEDENTARIA (Audouin and Milne Edwards 1834, pp. 24-26). The separation is based on the development of the anterior end and the life habits of the included species. The errants are supposed to have a large number of equal body-segments.

Why are polychaete worms important to benthic environment?

If any state- ments are to be made about the biology of the benthic environments, some note must be taken of the poly- chaetes. Furthermore, the keeping of some of these animals in culture has proved feasible, and some polychaetes even have become famous for their value as test animals in polluted areas.