Class polychaeta - classification of coelom, Biology

Class Polychaeta - Classification of Coelom

There are mainly marine forms with distinct head, having eyes and tentacles, segments have lateral projections of the body wall termed as parapodia which carry bundles of setae. These animals do not have clitellum. Sexes are separating (dioecious). They have no different or permanent sex organs, but their gonads consist of masses of developing gametes arising as swellings of Peritoneum. Eggs generally develop into trochophore larva. Many forms reproduce asexually by budding. ? Most of the polychaetes are 5-10 cm long. They live below rocks and in crevices, or burrow in mud. Some build tubes. Other is pelagic. These animals are generally divided into

(1) Errant forms on the one hand that are freely moving, pelagic, active burrowers, crawlers and the tube worms which leave their tubes for several purposes. On the other hand

(2) The sedentary forms do not leave their tubes or burrows but may generally expose just only their heads outside.

Errant polychaete structure may be considered classic of a generalised polychaete. The prostomium is very well developed, with several sense organs such as eyes, antennae, palps and the nuchal organs. Prostomium is dorsal and preoral projecting over the mouth. The peristomium that is the first segment carries the mouth. The predatory forms have jaws in the mouth. The peristomium is often fused along with one or more subsequent segments forming the head. These segments as well usually carry sensory structures, but their parapodium as well bears bundles of chitinous setae in the setal sacs. Nereis is a typical example. A cross section of its body by one of its middle segments shows well its internal organisation.

Posted Date: 2/2/2013 12:31:06 AM | Location : United States







Related Discussions:- Class polychaeta - classification of coelom, Assignment Help, Ask Question on Class polychaeta - classification of coelom, Get Answer, Expert's Help, Class polychaeta - classification of coelom Discussions

Write discussion on Class polychaeta - classification of coelom
Your posts are moderated
Related Questions
Corpus Allatum and Juvenile Hormone The corpora allata are rounded glands attached to the posterior side of every corpus cardiacum making a compact body just behind the brain.

Q. What are the two divisions of the angiosperms? The angiosperms are divided into dicotyledonous and monocotyledonous.

the concept that new varieties of organisms are still evolving is best supported by the.......?

Q. Explain about Mandible? In the mandible, attached keratinized tissue normally atrophies with the underlying bone. As a result there is generally a relatively narrow band of

Q. Show Cardiovascular Risk Factors? It must be coming in your mind several times that why do some people suffer from heart disease while others do not? Well the most obvious r

Fishes- Regeneration in Vertebrates Several different parts of the fish body will re-grow. Plucked scales are promptly replaced by new ones and amputated gill filaments can re

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. Indicate the probability of producing: An aB phenotype from a cross AaBb x AaBB

Sericulture : This is related to silk worms. Sericulture is also known as silk farming. Sericulture is rearing of silkworms for the production of raw silk. There are many types of

Filaments of a sarcomere in a skeletal muscle When the overlap between the thin and thick filaments of a sarcomere in a skeletal muscle is decreasing,    A. The total lengt

Do phylogenetically proximal species have cells with proximal chromosome counts? The number of chromosomes typical of every species is proximal for phylogenetically proximal sp