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

Productivity in medical transcription, Describe several factors which affec...

Describe several factors which affect Productivity in Medical Transcription. Definition of Medical Transcription Show the various factors thataffect Productivity in Medi

Health conditions, 2. Mr Konarski, 73 years old, lives in a high-level care...

2. Mr Konarski, 73 years old, lives in a high-level care facility. He has dementia of the Alzheimer''s type, osteoarthritis in both knees and ankles, and hypertension, which is con

Which phase of the menstrual cycle does nidation occur, Q. What is nidation...

Q. What is nidation? In which phase of the menstrual cycle does nidation occur? Nidation is the implantantion of the embryo in the uterus and Nidation takes place around the 7t

What are the major features of the meristematic cells, What are the major f...

What are the major features of the meristematic cells? And why do these cells need to have a high mitotic rate? The Meristematic cells have very thin cell walls, a well-central

Studying leaf arrangements, Studying leaf arrangements Observe as many ...

Studying leaf arrangements Observe as many growing plants as possible by looking down on them from above. Draw sketches of the dissimilar patterns of leaf arrangement.

Describe aerobic respiration in krebs cycle, Q. Until the Krebs cycle, aero...

Q. Until the Krebs cycle, aerobic respiration can be described without mentioning oxygen, the chemical element after which the reaction gets its name. Where in the process does thi

Explain the term health, Explain the term 'health' Mention any two ways of ...

Explain the term 'health' Mention any two ways of maintaining it. Why does a doctor administer tetanus antitoxin and not a tetanus vaccine to a child Injured in a roadside acci

What are the main respective constituents of cell walls in, What are the ma...

What are the main respective constituents of cell walls in bacteria, protists, fungi and plants? In bacteria the cell wall is made of peptidoglycans; between protists algae hav

Can you explain about cardiomyopathies, Q. Can you explain about Cardiomyop...

Q. Can you explain about Cardiomyopathies? Cardiomyopathy is a primary disorder of heart muscle that may cause cardiac dysfunction and is not related to any obvious disease pr

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