Bilateral - metazoa, Biology

Assignment Help:

Bilateral - Metazoa

Bilaterally symmetrical animals have the major axis running from head (anterior) to tail (posterior). They have a ventral (lower) and dorsal (upper) surface that are different from each other. They have only two sides that look alike, the right and left. The animal can be divided into just two identical halves through a plane which passes from anterior to posterior end. Almost all animals including human beings except for sponges, ctenophores and cnidarians show bilateral symmetry.

Adult echinoderms, though radially symmetrical (pentamerous) have larvae that are bilateral. This is because they have evolved from bilaterally symmetrical ancestors. In general, bilateral animals that adopt a sessile existence commonly exhibit a shift towards radial symmetry. The shift may be slight as in acorn barnacles where only protective circular wall plates are arranged radially or the shift may be profound as in the case of sea stars or starfishes. Bilateral animals are called Bilateria.


Related Discussions:- Bilateral - metazoa

Process of conducting system of the heart, Impulses reaching the AV node fr...

Impulses reaching the AV node from the atria are delayed a little as they pass through the trunk and crura. The impulses first reach the papillary muscles and their contraction clo

Can you explain about garden and green house, Q. Can you explain about Gard...

Q. Can you explain about Garden and Green House? Public parks and gardens are centres of aesthetic beauty and serve as places of recreation. Botanic Garden is a living resposit

Define terms umbra and penumbra, Define the terms umbra and penumbra, and d...

Define the terms umbra and penumbra, and describe how they relate to solar eclipses.

Why is it important to study biology, Why is it important to study biology?...

Why is it important to study biology? By studying biology, you can create informed decisions on issues that impact you and society, like environmental issues, health, and tech

Define chromium toxicity, Define Chromium Toxicity? Trivalent chromium,...

Define Chromium Toxicity? Trivalent chromium, the form of chromium found in foods and supplements, is least toxic. Oral supplements upto 800 to 1000 mcg per day appear to be sa

Define advantages for underwater weighing method, Define Advantages for und...

Define Advantages for underwater weighing method? This method is currently considered the "gold standard in percent body fat measurement (with the coming up of DEXA, the de

Regents for estimation of vitamin c - colorimetric method, Define Regents f...

Define Regents for Estimation of Vitamin C - Colorimetric Method? 1. 2, 4 dinitrophenylhydrazine reagent - Dissolve 2 g of dinitrophenyl hydrazine in 100 ml of 9N sulphuric aci

What is genetic engineering, Q. What is genetic engineering? Genetic en...

Q. What is genetic engineering? Genetic engineering, It is also known as molecular cloning or gene cloning, is artificial recombination of nucleic acid molecules in a test tube

Urolithiasis, Ur o l it h i a s i s The presence of calculi (u...

Ur o l it h i a s i s The presence of calculi (urolith) in the urinary system is termed as urolithiasis, and the disease is characterized by distension of bladder and

Define the cooper''s run (12 minute run) method, Define the Cooper's Run (1...

Define the Cooper's Run (12 minute run) Method? To undertake this test, a 400 metre running track is required-marked every 100 m and a stop watch. The test comprises of noticin

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