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 class asteroidea, What is Class Asteroidea ? Sea stars are prob...

What is Class Asteroidea ? Sea stars are probably one of the most recognizable of all Echinoderms. Often beautifully colored and symmetrical, they are predators that feed vorac

How aggregation occur in sickle-cell anemia, How does aggregation occur in ...

How does aggregation occur in sickle-cell anemia? Place the steps in the correct order from no aggregation to sickle red blood cell. Note that deoxyhemoglobin is generally in the T

Determine the effect of drug on the blood pressure of rats, A scientist wan...

A scientist wanted to study the effect of a drug on the blood pressure of rats. She set up an experiment in which the experimental group consisted of rats that were injected with a

Surrogacy, what is surrogate motherhood

what is surrogate motherhood

How do plants solve the problem of transporting substances, How do plants s...

How do plants solve the problem of transporting substances throughout their tissues? In bryophytes the substance transport is completed by diffusion. In tracheophytes (pteridop

Contraindications for beta-blockers, Reversible airways obstructive disease...

Reversible airways obstructive disease, advanced heart block, or episodic decompensation.  Vasodilators Agents that dilate arteriolar smooth muscle and lower peripheral vascu

Heart in mammals, Birds and Mammals - Heart is 4 chambered. 2 au...

Birds and Mammals - Heart is 4 chambered. 2 auricles & 2 ventricles. Sinus venosus & truncus arteriosus absent. Arteriovenous heart. Double circulation i.e. pre

Embryology in relation to taxonomy, Q. Embryology in relation to taxonomy? ...

Q. Embryology in relation to taxonomy? Embryological information has been used for taxonomic purposes at various levels of classification. You know of a very basic division of

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