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

Which chemical substances produced by water photolysis, Q. What are the che...

Q. What are the chemical substances produced by water photolysis and what is the destination of each of those substances? Free electrons, molecular oxygen and hydrogen ions are

Determine the genotypes and phenotypes, Determine the genotypes and phenoty...

Determine the genotypes and phenotypes of the F1 generaiton from a colour blind father and a mother who is homozygous for normal colour vision

National health service systems, Normal 0 false false false...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Microbodies, Microbodies Peroxisomes and glyoxysomes are microbodies fo...

Microbodies Peroxisomes and glyoxysomes are microbodies formed from ER which superficially resemble the lysosomes. Peroxisomes are spherical bodies limited by a single membrane

Cells are miniature chemical factory, Cells is a Miniature Chemical Factory...

Cells is a Miniature Chemical Factory Due  to its incessant metabolic processes, a living   cell earns the  attribute  of a  miniature chemical factory   metabolites and  free

Interspecific sterility, In interspecific sterility, the failure in mating ...

In interspecific sterility, the failure in mating occurs because of inability of the sperm to reach the egg in animals and the pollen to reach ovules in plants. In plailts interspe

Explain ventilation and niv, Explain Ventilation (NIV)? This refers to ...

Explain Ventilation (NIV)? This refers to the use of mechanical ventilatory support without the use of an endotracheal tube. NIV may be by the application of a continuous posit

Knocking and octane number, Mixture of gasoline and air is used as fuel in ...

Mixture of gasoline and air is used as fuel in internal combustion engine. It is highly compressed and then ignited. 1.      The process involves four strokes : 2.      The f

Explain 1st type of hypersensitivity, It is IgE mediated hypersensitivity. ...

It is IgE mediated hypersensitivity. Typical manifestations contain asthma, food allergies, eczema, hay fever etc.

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