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 are the main gas exchange organs of the plants, What are the main gas ...

What are the main gas exchange organs of the plants? How is the process accomplished? In the covering of the leaves and of the primary structure of the stem gas exchange is mad

Explain the term - differential reinforcement, Differential reinforcement ...

Differential reinforcement (Training of incompatible behaviour)- Differential reinforcement of incompatible behaviour (DRI) is used to decrease a frequent behaviour without pun

What do atp and adp mean, What do ATP and ADP mean? What are the roles of t...

What do ATP and ADP mean? What are the roles of these molecules for the cellular energetic metabolism? ATP is an abbreviation of adenosine triphosphate, a molecule made of aden

Internet meanings for: URL HTTP COOKIES, Internet meanings for:...

Internet meanings for: URL HTTP COOKIES BAUD WWW COMP What Is The Internet? What do you need to connect to the Internet? Advantages and disadvantages of the Ne

What structure replaces the graafian follicle, After ovulation:- (a) ...

After ovulation:- (a) what structure replaces the Graafian follicle (b) what hormone does it produce?   (a) After ovulation, the follicle is replaced by the cor

Define lipoprotein metabolism, Q. Define Lipoprotein Metabolism? Lipopr...

Q. Define Lipoprotein Metabolism? Lipoproteins serve to transport absorbed dietary fat and endogenously synthesized cholesterol and triglyceride. Nevertheless, it is possible t

Phylum annelida, what so special for phylum annelida

what so special for phylum annelida

Describe gastrovascular cavity in detail, Describe Gastrovascular cavity in...

Describe Gastrovascular cavity in detail? The name given to the internal cavity of cnidarians. A blind-ended (incomplete) gut with only one opening. Food is to be digested and

What is the prevailing wind direction, what is the prevailing wind directio...

what is the prevailing wind direction in equatorial regions affected by the trade winds? a) The wind blows from east to west b) the wind blows from west to east

Vertebrata, VERTEBR A T A It is divided into two parts -        1. ...

VERTEBR A T A It is divided into two parts -        1. Agnetha                    2. Gnetha S.No. C haracter A gnetha G

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