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

From molecules to the first cell, From Molecules to the First Cell The ...

From Molecules to the First Cell The prebiotic conditions on the earth in all probability were volcanic eruptions, lightning and heavy rains. There was no trace of free oxygen

Plasmotomy, draw a well labled diagram of plasmotomy

draw a well labled diagram of plasmotomy

What is guided bone regeneration, What is Guided bone regeneration Gui...

What is Guided bone regeneration Guided bone regeneration (GBR) allow the practitioner to place implants in patients who would not have received this treatment option a few y

Dissolved oxygen - aquatic habitats, Dissolved oxygen - Aquatic Habitats ...

Dissolved oxygen - Aquatic Habitats Oxygen in the terrestrial ecosystems occurs in the atmosphere along with other gases in a certain fixed concentration however, in aquatic e

What is lymphatic network, What is Lymphatic Network? The lymphatic net...

What is Lymphatic Network? The lymphatic network consists of the lymphatic vessels, which circulate lymph throughout the body. Lymph is a liquid which carries out exchange of g

Reproduction., in oogenesis only on functional egg cell is normally formed ...

in oogenesis only on functional egg cell is normally formed from primary oocyte. Briefly explain

Types of biogeochemical cycles, Types of Biogeochemical Cycles There a...

Types of Biogeochemical Cycles There are two basic types of biogeochemical cycles, gaseous and sedimentary. In the gaseous type of biogeochemical cycle there is a prominent ga

What happens at the molecular level, An enzyme isolated from a mutant bacte...

An enzyme isolated from a mutant bacterium grown at 20 degrees celsius works in a test tube at 20 degrees celsius but not at 37 degrees celsius( 37 degrees celsius is the temperatu

Cell-cycle controls, • Cancer cells do not respond normally to the body's c...

• Cancer cells do not respond normally to the body's control mechanism. o They divide excessively and invade other tissues. o If left unchecked, they can kill the organism. •

Right atrial pressure, RAP can be determined semiquantitatively by assessi...

RAP can be determined semiquantitatively by assessing collapse of the inferior vena cava during inspiration. The inferior vena cava is imaged subcostally and its diameter is exa

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