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

How can we check bp without stethoscope, How can we check BP without stetho...

How can we check BP without stethoscope In this case the procedure is same except you place your hand on radial pulse. You can read systolic pressure only by this method. -

What are the functional divisions of the nervous system, What are the funct...

What are the functional divisions of the nervous system? Functionally the nervous system can be separated into the somatic nervous system and visceral nervous system. The so

How gender affects the bmr, How Gender affects the bmr? We have already...

How Gender affects the bmr? We have already emphasized earlier that sex difference in metabolic rates are primarily attributable to difference in body size and composition. Wom

Features of amphibian gastrulation, Features of Amphibian Gastrulation ...

Features of Amphibian Gastrulation Major features of amphibian gastrulation are: Ectoderm surrounds the embryo by Epiboly. Gastrulation is initiated by a limited i

Ammonotelism - excretion, Normal 0 false false false EN...

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

Define the term parasites, Normal 0 false false false E...

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

Leptontene and zygotene, Leptontene: The chromosomes becomes visible,...

Leptontene: The chromosomes becomes visible, shorten and thick. The size of the nucleus increase. The homologous chromosomes start getting closer to each other. Z

Explain the types of modified gellan gum, Explain the types of modified gel...

Explain the types of modified gellan gum There are 3 types of modified gellan gum.  (a) High acetyl gellan (partially deacetylated), which provides a thermo reversible gel,

How depolarization of the neuronal plasma membrane generated, How is the de...

How is the depolarization of the neuronal plasma membrane generated? How does the cell return to its original rest? When the neuron receives a stimulus by the binding of neurot

Prognosis, The course and ultimate prognosis of ARF is usually directly rel...

The course and ultimate prognosis of ARF is usually directly related to the severity of carditis. The course and prognosis also depends upon recurrence of rheumatic fever. In pre-p

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