Regional specialisation, Biology

Assignment Help:

Regional Specialisation

Regional specialisation takes place usually by three processes –

1) Restriction of certain structures to a few segments, for example, gonads are restricted to a few specialised genital segments in annelids (e.g. earthworm).

2) Structural divergence of segmental structures to perform different functions. For example some segmental appendages may be modified from those suitable for locomotion to those adapted for grasping or chewing, (e.g. insects)

3) Fusion of segments along the length of the animal. For example, fusion of anterior segments to form the head. The head of Nereis consists of the acron and two other segment while that of Drosophila is composed of five segments.

The second significant feature of metameric segmentation is its importance in the ' locomotion of soft bodied animals. The acoelomates animals use their musculature of longitudinal and circular muscles for locomotion but the evolution of a coelomic cavity has allowed the fluid to act as hydraulic skeleton. In invertebrates like annelids, muscles of the body wall act against this pressure. When circular muscles Contract, hydrostatic pressure on coelomic fluid will result in lengthening of the body; when longitudinal muscles contract, it will result in widening of the body. Since metameric segmentation results in compartmentalisation of the body, this elongation and widening of the body can be restricted to a few segments at a time.

This local change in the shape of the elongate body increases the locomotory efficiency. The broadened part of the body can be firmly fixed against the burrow especially if there are clinging structure such as setae and the lengthening of the body will produce considerable thrust resulting in progression of the animal. Thus the alternate peristaltic waves enable the animal to move forwards faster and efficiently.


Related Discussions:- Regional specialisation

What is the basic morphology of a protozoan cell, What is the basic morphol...

What is the basic morphology of a protozoan cell? Protozoans are eukaryotic cells so they have organelles and structures common to this part of cell: endoplasmic reticula, Gol

Explain the history of plant classification, Explain the History of Plant C...

Explain the History of Plant Classification? Before Darwin's theory of evolution and publication of his epoch making work 'Origin of Species' in 1959 no outstanding basis for

Molecule that transports oxygen in red blood cells, Q. What is the name of ...

Q. What is the name of the molecule that transports oxygen in red blood cells? The respiratory pigment of the red blood cells is hemoglobin.

Define interaction of vitamin c with riboflavin, Define interaction of Vita...

Define interaction of Vitamin C with Riboflavin? The two coenzyme forms of riboflavin are FMN and FAD. They are found in a large number of systems which function in the metabol

Reproduction, Which are the larval stages of Porifera?

Which are the larval stages of Porifera?

Lungs - respiration, Lungs - Respiration Lungs can be simple, characte...

Lungs - Respiration Lungs can be simple, characterised by air exchange with surrounding environment by diffusion only. These are called the diffusion lungs and are present in

Enumerate the anatomic consequences of edentulism, Q. Enumerate the anatomi...

Q. Enumerate the anatomic consequences of edentulism? The anatomic consequences of edentulism include the effect of edentulism on bone and soft tissues. Basal bone forms the de

Explain adverse effects of amprenavir, Explain Adverse effects of Amprenavi...

Explain Adverse effects of Amprenavir  The most common adverse effects have been nausea, vomiting (especially in combination with zidovudine), perioral paresthesias and rash (J

Zoology, structural adaptation of mammalian alimentary canal

structural adaptation of mammalian alimentary canal

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