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

What is nucleotides, What is Nucleotides? Nucleotides are the basic b...

What is Nucleotides? Nucleotides are the basic building blocks of nucleic acids. Each nucleotide is composed of a nitrogen base, a 5-carbon sugar called a pentose, and an ass

Ozone layer and its depletion, About 90% of ozone of atmosphere resides in ...

About 90% of ozone of atmosphere resides in stratosphere (16 to 40 km) layer of atmosphere as ozone layer. It protects life on this planet from harmful U.V. radiations. In absence

What are the main cellular features of fungi, What are the main cellular fe...

What are the main cellular features of fungi? There are unicellular and pluricellular fungi. All fungi are eukaryotes and heterotrophs. Fungi have cells with cell wall made

What are the antigens and antibodies of abo blood system, What are the anti...

What are the antigens and antibodies of each blood type of the ABO blood system? Type A: antigen A, antibody anti-B. Type B: antigen B, antibody anti-A. Type AB: antigens A and

Define fluids required for underweight - nutritional care, Define Fluids re...

Define Fluids required for underweight - nutritional care? Take fluids only after a meal instead of with or before meals so that food intake is not reduced. High calorie nouris

Vitamin - k, VITAMIN - K Also known as naptho quionone / anti haemo...

VITAMIN - K Also known as naptho quionone / anti haemorrhagic vitamin / coagulation vitamin / menadone . It requires for formation of blood clotting factor prothrombin.

ALGAE., HOW ARE THE ORIGIN AND EVOLUTION OF ALGAE..

HOW ARE THE ORIGIN AND EVOLUTION OF ALGAE..

What are the conventional signs used in genetic family trees, What are the ...

What are the main conventional symbols and signs used in genetic family trees? In genetic family trees the male sex is usually shown by a square and the female by a circle. Cro

Pollen biology, Pollen Biology Fluorescence microscopy coupled with bi...

Pollen Biology Fluorescence microscopy coupled with biochemical analysis has helped resolve the differential activity of the enzyme, β-l, 3- glucanase that catalyses the disso

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