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

Instrument examination and care, Instrument Examination and Care Cleani...

Instrument Examination and Care Cleaning instruments, provides a good opportunity to examine, replace or remove damaged instruments; lubricate items such as handpieces; and oth

Goals of dietary treatment for dyslipidemia, Q. Goals of Dietary Treatment ...

Q. Goals of Dietary Treatment for dyslipidemia? The goals of dietary management (alone or conjunction with exercise or with lipid lowering drugs) are to reduce the total fat, s

What is the function of the vitellus in the vertebrate egg, Q. What is the ...

Q. What is the function of the vitellus in the vertebrate egg? How are these eggs classified according to the amount of vitellus within them? Vitellus (yolk) is the nutritive m

Find the net charge of the predominant form asp, Determine the net charge o...

Determine the net charge of the predominant form Asp at (a) pH 1.0, (b) pH 3.0, (c) pH 6.0, and (d) pH 11.0?

Explain acute mr murmur in heart dieases, Explain Acute MR Murmur in heart ...

Explain Acute MR Murmur in heart dieases? MR due to ruptured papillary muscle, ruptured chordae tendinae, or due to Infective Endocarditis/Myocardial infarction. Characteri

Blastula, Blastula is the ball of cells surrounding a fluid-filled cavity ...

Blastula is the ball of cells surrounding a fluid-filled cavity (known as blastocoel) which is produced by the cleavage of a zygote.

Why are agricultural fields often less stable, Why are agricultural fields ...

Why are agricultural fields often less stable than natural communities in the similar area? Because agricultural fields usually having one species of crop plant, they have low

Fowl typhoid, F o wl typhoid Fowl typhoid is caused by Salmonella G...

F o wl typhoid Fowl typhoid is caused by Salmonella Gallinarum , a Gram negative bacillus in the family enterobacteriaceae (serogroup D). Chickens are the natural hosts fo

Benthic zone - organisation of the marine ecosystem, Benthic Zone - Organis...

Benthic Zone - Organisation of the Marine Ecosystem The benthic zone is divisible into sub zones horizontally. These are depicted in a cross section portion of the marine habi

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