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

Light and heavy soils-physical properties of soil, Light and Heavy Soils ...

Light and Heavy Soils The presence of silt and especially clay in a soil imparts to it a fine texture, and a slow water and air movement. Such a soil is highly plastic becoming

What is the typical localization of the tropical forests, What is the typic...

What is the typical localization of the tropical forests regarding latitude? The Tropical rain forests, like the Congo forest and the Amazon forest, are typically located in lo

Circulatory systems in animals, Circulatory Systems in Animals In anim...

Circulatory Systems in Animals In animals that have efficient circulatory systems and readily permeable vascular skins, gas exchange occurs through the integument. Thus we fin

Rituals , Rituals: The social life of  the earliest human groups or tri...

Rituals: The social life of  the earliest human groups or tribes revolved around food gathering. To begin with, they must have collected anything they could eat-seeds,  nuts, f

Investigations of food borne diseases, Q. Investigations of food borne dise...

Q. Investigations of food borne diseases? Most important aspect of food borne disease would be to collect the right sample. Now, what procedure to follow while collecting th

What are dopaminergic neurons, Q. What are Dopaminergic neurons? Dopam...

Q. What are Dopaminergic neurons? Dopamine Dopaminergic neurons occur in two closely connected groups: Ventral tegmental area (VTA) of the midbrain and Substantia nigra,(i

Name diseases caused by viruses, Name three diseases caused by viruses. ...

Name three diseases caused by viruses. There are many diseases caused by virus. Virus diseases include colds, influenza, herpes, mumps, measles, chicken pox, rubella, hepati

What are the preservation of insulin, What are the Preservation of Insulin ...

What are the Preservation of Insulin Regular insulin is stable for 18 months at 23.8 0 C and Lente insulin are stable for 24 months at this temperature. Although refrigeration

Eye - conjuctiva, CONJUNCTI V A - Ectodermal in origin. Formed by epi...

CONJUNCTI V A - Ectodermal in origin. Formed by epidermis. It is thin, transparent covers cornea. Made up of stratified epithelium. It has 2 parts - (i) Ocular conjunct

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