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

Respiratory system, describe the structure of a lung in terms of covering m...

describe the structure of a lung in terms of covering membranes and cavities

What are the main human diseases caused by prions, What are the main human ...

What are the main human diseases caused by prions? The main called human diseases of such type are the Creutzfeldt-Jacob disease (CJD), the kuru and the Gerstmann-Sträussle-Sch

Bovine spongiform encephalopathy (bse), B o vi n e spongiform encephalo...

B o vi n e spongiform encephalopathy (BSE) Bovine spongiform encephalopathy (BSE) is a transmissible, neurodegenerative, fatal brain disease of cattle characterized by post

5.4 assessment from the book, Briefly explain why cutting a flatworm into p...

Briefly explain why cutting a flatworm into pieces would not kill it

Define the respiratory chain process, Q. Where in mitochondria does the pro...

Q. Where in mitochondria does the process called respiratory chain occur? Which are the products of the Krebs cycle used in that final phase of the aerobic respiration? Respira

Define the clinical success for the root canal treatment, Define the Clinic...

Define the Clinical success for the Root Canal Treatment a) Absence of pain and swelling. b) Disappearance of sinus tract. c) No evidence of soft tissue destruction, incl

Explain binding of pigments - proteins, Binding of  Pigments, synthetic dy...

Binding of  Pigments, synthetic dye In  addition  to water, lipids and  volatile  flavours,  food proteins  can  bind  a number of other  substances  by  weak interactions  or

What is master gland, Which of the below is usually referred to as "master ...

Which of the below is usually referred to as "master gland" because it regulates so many body activities? Is it: a) Pituitary gland b) Thyroid gland c) Adrenal gland d

Regulation of testicular, Normal 0 false false false EN...

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

Deficiency diseases-rickets, Rickets Rickets is a complex mineral defic...

Rickets Rickets is a complex mineral deficiency disease of young, growing animals. It is characterized by defective mineralization of growing bones, persistence of hypertrophic

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