How many species of polychaetes are there?

polychaete, any worm of the class Polychaeta (phylum Annelida). About 8,000 living species are known.

What do polychaete worms eat?

Polychaetes also include active predators, scavengers and grazers of algae. Many polychaetes are eaten by other polychaetes and other marine invertebrates as well as fish and wading birds.

Where can polychaetes be found?

the ocean
the bristleworms Of the approximately 9000 species of annelids, more than 8000 are polychaetes. These segmented worms are among the most common marine organisms, and can be found living in the depths of the ocean, floating free near the surface, or burrowing in the mud and sand of the beach.

Can polychaetes live on land?

Underwater polychaetes have eversible mouthparts used to capture prey. A few groups have evolved to live in terrestrial environments, like Namanereidinae with many terrestrial species, but are restricted to humid areas. Some have even evolved cutaneous invaginations for aerial gas exchange.

What type of body organization is found in polychaetes?

The body in many species, especially in the sedentary polychaetes, is separated into two or three regions. The cells constituting the epidermis (outermost cell layer) are usually simple columnar epithelial cells covered by a cuticle; parts of the body may be ciliated, especially in smaller forms.

What are the characteristics of a polychaete?

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 breathe?

Respiration is entirely through the body wall in some polychaetes, and partially so in most. Many species have thin-walled extensions of the body surface, i.e., gills, used for gas exchange; most commonly the gills are extensions of the parapodia.

Are polychaete predators?

The nereid polychaetes are free-moving predators that will consume large and small invertebrates using large proboscis jaws; they will also consume large amounts of detritus in the absence of prey items (Figure 5). Other families have filter-feeding and deposit-feeding representatives.

What are the essential features of polychaetes?

The following are the salient feature exhibited by Polychaetes:

  • They are dioecious and multi-portioned.
  • They possess separate sexes.
  • Fertilization is external.
  • It exhibits metamerism and segmentation.
  • It possess closed vascular system.
  • It has chain type of nervous system.

How do polychaetes respire?

Are polychaetes predators?

What is the habitat for most polychaetes?

Annelids are found worldwide in all types of habitats, especially oceanic waters, fresh waters, and damp soils. Most polychaetes live in the ocean, where they either float, burrow, wander on the bottom, or live in tubes they construct; their colours range from brilliant to dull, and some species can produce light.