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

Hypothesis - nursing research, Hypothesis: The  spelling of hypothesis...

Hypothesis: The  spelling of hypothesis when written  as  "hypotheses"  indicate plural. The hypothesis is a statement or declaration of  the expected outcome of a research st

Levels of biodiversity, There are three levels of diversity viz. genetic, ...

There are three levels of diversity viz. genetic, species and ecosystem diversity. In effect, these levels cannot be separated. Each is important, interacting with a nd influencin

Rbc & wbc, difference between RBC and WBC for homework

difference between RBC and WBC for homework

Explain the peptones - complex media, Explain the Peptones - Complex Media?...

Explain the Peptones - Complex Media? Peptones are protein hydrolysates obtained by partial digestion of meat, casein, soya meal, gelatin or other protein source. These provide

Can you explain lane and eynon method, Q. Can you explain Lane and Eynon me...

Q. Can you explain Lane and Eynon method? Reducing sugars are those, which have free sugar groups (e.g. glucose, fructose etc.) and hence may be estimated directly by titrat

Define foaming properties of proteins, Define Foaming Properties, Binding o...

Define Foaming Properties, Binding of Flavour and Other Substances? To understand the foaming properties of proteins, we need to know some basic aspects of foam foods. Foam foo

How thirst and satiety influence water intake, How Thirst and satiety influ...

How Thirst and satiety influence water intake? Thirst and satiety influence water intake, apparently in response to changes sensed by the mouth, hypothalamus and nerves. When t

Pathology of mitral regurgitation, Q. Pathology of mitral regurgitation? ...

Q. Pathology of mitral regurgitation? During left ventricular systole as the pressure rises in left ventricle, blood is pumped simultaneously both into aorta and left atrium. T

Describe the organization of the vascular plant body, Describe the Organiza...

Describe the Organization of the Vascular Plant Body? A typical plant body consists of two distinct systems: a root system and a shoot system. The root system is usually below

Chemical energy of matter, Chemical energy of matter : As is obvious from ...

Chemical energy of matter : As is obvious from  the above  account  living cells  obtain  energy  by breaking   C-C and C-H bonds  of organic  matter under the  process of catabol

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