Segmentation - metazoa, Biology

Assignment Help:

Segmentation - Metazoa

Segmentation or metamerism is the division of the body into smaller transverse compartments along the anterior-posterior axis. Segmentation is widespread among animals, with true segmentation occurring in annelids, arthropods and most chordates though some other groups show superficial segmentation of ectodermal body wall. Fundamentally there are three body forms. First, monomeric where there is no division of the large body cavity at all. Ascaris has this type of body form. Second, oligomeric where the body cavity is divided into three and each region has a separate body cavity hooks with no divisions on the abdomen Phorona is a warm with this body plan'. Third metameric in which the body is divided into head, thorax and abdomen and where abdomen is further divided into a chain of segments.

2177_Segmentation - Metazoa.png

                                                        Figure: superficial segmentation seem in tape-worms

A Segmented body forms can be seen in tape worms, annelids arthropods and' chordates. Of these segmentation in tape worms is quite different from that seen in the others. We can observe that segmentation in tape worm is superficial, a series of ring like creases develop in the cuticle and the body wall which facilitate bending and telescoping of the body. But this segmentation is strictly ectodermal and this segmentation is a reproductive adaptation. The segments of the entire body are in a continuous process of being produced matured and discarded. The new segments grow in the neck region and the older ones are detached from the posterior end, Each segment functions as an independent unit without having' any vital connections with the other.


Related Discussions:- Segmentation - metazoa

Give example of ex-situ conservation, Which one of the following is an exa...

Which one of the following is an example of ex-situ conservation? 1. Wildlife sanctuary 2. Seed bank 3. Sacred groves 4. National park Seed bank

The skeletal system, Where does cartilage occur in a joint and what is its ...

Where does cartilage occur in a joint and what is its function ?

Explain disease motion sickness, Motion Sickness  The pathogenesis of m...

Motion Sickness  The pathogenesis of motion sickness is poorly under- stood. The prescription cholinergic blocker scopolamine in a patch or oral formulation can decrease sympto

Non-renewable energy sources, In many countries of Asia biomass contributes...

In many countries of Asia biomass contributes l argely as a source of primary energy. People in rural areas at the peripheries of forests, continue to collect fuel wood from adjace

DNA, where does the free nucleotides present in the nucleus come from

where does the free nucleotides present in the nucleus come from

Neo-lamarckism, NEO-LAMARCKISM Modem modified form of Lamarck theory...

NEO-LAMARCKISM Modem modified form of Lamarck theory is regarded as Neo-Lamarckism. Mc Dougall (1938) found that time taken for training the mice was reducing gradually

Difference between myosin and actin filaments, DIFFERENCE S BETWEEN MYOSIN...

DIFFERENCE S BETWEEN MYOSIN AND ACTIN FILAMENTS     Myosin filaments (primary filaments)   Actinfilament s (secondary filaments)

Butter, Ask question #Minimum 100 words role of micro organisms in preparat...

Ask question #Minimum 100 words role of micro organisms in preparation of butter accepted#

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