Class polychaeta - classification of coelom, Biology

Assignment Help:

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.


Related Discussions:- Class polychaeta - classification of coelom

What is biodiversity, What is biodiversity? Biological diversity is the...

What is biodiversity? Biological diversity is the several of species of living beings of an ecosystem. In ecosystems which are more bio diverse, as tropical forests, a great va

Describe splitting of in second heart, Describe Splitting of S 2 ? On...

Describe Splitting of S 2 ? On inspiration: The split widens as both A, and Pi move away from each other with p, moving out more. The negative intrathoracic pressure during

Explain phylum sarcdina, Phylum Sarcdina 1) They move by means of pseud...

Phylum Sarcdina 1) They move by means of pseudopodia (ralse feet) or similar structures. 2) They feed heterotrophically by phagocytosis.   Some examples: Amoeba, Entamo

What is sympatric isolation, A few individuals from a herd of deer are forc...

A few individuals from a herd of deer are forced to migrate to a new herd. This is an example of  resulting in.   a.  Gene flow; enhance in similarities between populations.

What do you mean by a dihybrid cross, A dihybrid cross: Determines the gene...

A dihybrid cross: Determines the genetic makeup of an organism always involves homozygous alleles. Always involves organisms that are heterozygous at all loci. Always involves alle

Describe about the term - neuropsychological assessment, Describe about the...

Describe about the term - Neuropsychological assessment Neuropsychological assessment has its roots in neurology, the branch of medicine that focuses on the nervous system and

Blood from a donor is sterile and stored in a sealed bag, Blood from a dono...

Blood from a donor is sterile and stored in a sealed bag, but it is still kept at 4°C. What is the advantage of keeping it at this low temperature?   At 4 °C, enzyme activi

Define the principle behind cyanmethemoglobin method, Define the Principle ...

Define the Principle behind Cyanmethemoglobin Method? The principle behind the cyanmethemoglobin method is as follow: Principle The haemoglobin is treated with a reagent con

What are the two divisions of the autonomic nervous system, What are the tw...

What are the two divisions of the autonomic nervous system? The autonomic nervous system is separated into the sympathetic nervous system and the parasympathetic nervous system

What is a glucose tolerance test, What is a glucose tolerance test? A g...

What is a glucose tolerance test? A glucose tolerance test, usually conducted in the 24 to 28 weeks of pregnancy measures levels of sugar (glucose) in the mother's blood. Abnor

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd