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 nuclear proteins , The nucleus has an inner and an outer memb...

The nucleus has an inner and an outer membrane and is perforated through 3000-4000 nuclear pores. Each pore having of a nuclear pore complex of more than 100 several proteins organ

Name three characteristics of mitochondria, Name three characteristics of m...

Name three characteristics of mitochondria and chloroplasts that support the endosymbiotic hypothesis of eukaryotic evolution. Both organelles replicate independently of the ce

Why the diluent is distilled water, A drug has a molec. weight of 200. How ...

A drug has a molec. weight of 200. How many grams would you use to make 100 ml of a solution that is isotonic (for man)? Assume that the diluent is distilled water and that the dru

What do you understand by pericardium, Q. What do you understand by Pericar...

Q. What do you understand by Pericardium? Pericardium is the covering sac of the heart. The pericardium prevents acute cardiac chamber dilatation. Acute pericarditis, pericardi

Deifition, what''s the define of mitochodria

what''s the define of mitochodria

Describe a. the factors responsible for promoting lactation, Describe a. th...

Describe a. the factors responsible for promoting lactation, and b. the mechanism responsible for the cessation of lactation when a mother weans her baby.

Benthos - aquatic ecosystem, Benthos - Aquatic Ecosystem The benthos o...

Benthos - Aquatic Ecosystem The benthos or the benthic organisms are those found living in or on the bottom or benthic region of the water mass. They exhibit a variety of adap

Protein electrophoresis - measuring genetic diversity, Q. Protein electroph...

Q. Protein electrophoresis - Measuring Genetic Diversity? This method is now being used to measure genetic diversity. Genes contain the information required to produce enzymes

Indications for surgery-pericardial diseases, Indications for Surgery :  O...

Indications for Surgery :  Once diagnosis of constrictive pericarditis is made and confirmed by chest X-ray, ECG, echocardiogram, CT, MRI scan, cardiac catheterisation and angio,

Phototherapy unit, Phototherapy Unit Principle Photoisomerisat...

Phototherapy Unit Principle Photoisomerisation and photo-oxidation changes indirect bilirubin into water soluble substance. Operational Instruction Adjust

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