Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
What is the type of digestion that occurs in cnidarians? These animals have a digestive cavity and they make intracellular and extracellular digestion. The extracellular digest
In one year, a population size of 500 changed to 496. What is the per-capita rate of increase/decrease?
Explain the Indole Production Test? Many microorganisms produce an enzyme tryptophanase which oxidizes amino acid tryptophan to produce pyruvic acid, indole and ammonia. We can
Explain Food Sources of lron? lron is found in foods in one of the two forms i.e. haem or non-haem. In the human diet, the primary sources of haem iron are the haemoglobin and
Effects on Health - Water Pollution Water pollution deteriorates the quality of water used for drinking, bathing, swimming, recreation and irrigation. Water contaminated with
Q What are the nitrogen wastes? Nitrogen wastes are residuals derived from the degradation of proteins and they are made from chemical transformation of the amine group of amin
What is bioremediation? Bioremediation is the use of microorganisms, as bacteria, protists and fungi, to degrade noxious substances turning them into non toxic or less toxic su
The protein truncation test (ptt) gives an uncommon exception, targeting mutations that create shortened proteins, majorly premature translation termination. Ptt has various attrac
Placement of the Implant in an Infected Socket or a Pathologic Lesion Dental implants may fail due to: 1) Placement of the implant fixture into an infected socket (during im
Starch is one of the most common storage products in seeds. What happens to the starch before it can be used by the germinating seed? Starch is insoluble and has to be changed,
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd