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

Raw material for industry - impacts on biodiversity, Raw Material for Indus...

Raw Material for Industry - impacts on biodiversity The industry, producing goods and services, relies and impacts on biodiversity directly. Much of the raw material that goes

Results-types of surgery, Results: Early mortality for tricuspid valve re...

Results: Early mortality for tricuspid valve replacement is around six per cent. But depending on the patient's class of symptoms and the number of concomitant procedures, this c

Sample titration for determination of iodine number of lipid, Define Sample...

Define Sample titration for Determination of the Iodine Number of Lipids? With a clean dry pipette, accurately measure 0.3 mL of oil into a clean and dry iodination flask (Dupl

Define arterial vessels - arterioles and arteries, Q. What are arterial ves...

Q. What are arterial vessels, arterioles and arteries? Arterial vessels are every blood vessel that carries blood from the heart to the tissues, arterioles and Arteries are art

Pocket psedocyst-endodontics principles and practice, Pocket Psedocyst : le...

Pocket Psedocyst : lesions present as endodontic origins from canals . It makes lumens resemble granuloma . All lesions lined until root canal or apical foramen communicat

Determine the classification of colloidal systems, Classification of Colloi...

Classification of Colloidal Systems Thomas Graham referred to colloids as  the study of sub microscope dispersion. According to him, it dealt with the dispersed systems of a de

What is the law of limiting factors, What is the law of limiting factors? H...

What is the law of limiting factors? How would the rate of photosynthesis be affected if the soil water becomes limiting? Describe.

Explain kingdom protista, Kingdom Protista The protistans are a complex a...

Kingdom Protista The protistans are a complex and diverse group of organisms that are placed together simply because they are all single celled eukaryotes but some form rather sp

Blood, what are the component of hemoglobin

what are the component of hemoglobin

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