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

, comparitive table to explain the differences between the animals in chor...

comparitive table to explain the differences between the animals in chordate classes

Peroxisomes and glyoxysomes, PEROXISOMES AND GLYOXYSOMES Certain small ...

PEROXISOMES AND GLYOXYSOMES Certain small ovoid  unit membrane bound  sac like  cytoplasmic  organelles, resembling  lysosomes in size  and appearance  were  isolated  from var

Define the term - hemiplegia, Define the term - Hemiplegia The characte...

Define the term - Hemiplegia The characteristics of hemiplegia (again, hemi means "half") are loss of voluntary movements on one side of the body, changes in postural tone, and

Why is it necessary to maintain the ph level, Q Coming from the acid pH of ...

Q Coming from the acid pH of the stomach which pH level does the chyme find when it enters the duodenum? Why is it necessary to maintain that pH level in the small intestine? What

Define the carbohydrate and fat required for elderly, Define the Carbohydra...

Define the Carbohydrate and Fat required for elderly? Carbohydrate: It is usually recommended that approximately 55en% (percent of  energy) be provided from carbohydrate food

Periodicity - qualitative characters, Periodicity (Phenology, Aspection) ...

Periodicity (Phenology, Aspection) It refers to the study of seasonal changes in the community, that is, the periodic phenomena of organisms in relation to their climate. Peri

Female reproductive system - external genitalia, EXTERNAL GENITALIA - ...

EXTERNAL GENITALIA - Vestibule is covered by 2 pairs of lips labia majoris and labia minoris. At the anterior junction of labia minoris a small erectile clitoris presen

Define the control of tear production, Define the control of tear productio...

Define the control of tear production. Control of Tear Production The lacrimal secretary system was initially thought to be comprised of two parts, basic secretors and r

Digestive system of class asteroidea, Digestive System of Class Asteroidea ...

Digestive System of Class Asteroidea Most asteroids are scavengers or carnivores and feed on snails, bivalves, polychaets, other echinoderms, fish, sponges, sea anemones and 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