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

How vitamin c play important role in the preventionof cancer, How Vitamin C...

How Vitamin C play important role in the preventionof Cancer? Vitamin C based on research evidence plays an important role in the prevention and treatment of cancer. Its anti c

Define contains permitted synthetic food colour, Normal 0 fa...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

The nurse''s role in relieving the child''s stress, The Nurse's Role  in ...

The Nurse's Role  in Relieving  the Child's Stres s Turning passive experiences into active ones that facilitate the child's healthy - Problems-I  adjustment to hospitalization

Explain the transfer from liquid medium to solid media, Explain the Transfe...

Explain the Transfer from liquid medium to solid media? Here the steps involved include: 1. Inoculating loop is sterilized by incineration and allowed to cool, as described

Define modulation of transcription of cell cycle proteins, Modulation of th...

Modulation of the transcription of cell cycle proteins? The 1,25-(OH),D  compound (calcitriol), is present in the blood complexes to the vitamin D-binding  protein, a specific

Metallurgical coke, Metallurgical coke should have following characteristic...

Metallurgical coke should have following characteristics: 1.      Purity: low amounts of moisture, ash, sulphur & phosphorous should be present. 2.      Porosity: it should b

Skin cancer, SKIN CANCER: CAUSES AND TREATMENT PURPOSE: The objective of t...

SKIN CANCER: CAUSES AND TREATMENT PURPOSE: The objective of this assignment is to make you aware of the structure and function of your skin, what are the dangers that your skin ma

Difference between artificial and natural selection, Difference between Art...

Difference between Artificial selection and natural selection - S.No Artificial selection Natural selection 1. It

Explain iodophors, In these disinfectants, iodine is incorporated along wi...

In these disinfectants, iodine is incorporated along with a detergent. They are not as effective as hypochlorites against bacterial spore but also get inactivated in the pres

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