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

Benefits of cross-pollination, Benefits of Cross-Pollination Because o...

Benefits of Cross-Pollination Because of the specific benefits of cross-pollination, flowering plants have evolved many devices to prevent self-pollination and to encourage cr

Sunlight - aquatic habitats, Sunlight - Aquatic Habitats Sunlight is a...

Sunlight - Aquatic Habitats Sunlight is a major limiting factor for water bodies, since light rapidly diminishes as it passes down the column of water. The upper layers of the

Give an overview about operons, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 Various protein-codi

Which the dna is made based on the rna template, Q. Is there any situation ...

Q. Is there any situation in which the DNA is made based on the RNA template? What is the enzyme involved? The process in which the DNA is synthesized having as template a RNA

How do cells get energy for their functioning, Q How do cells get energy fo...

Q How do cells get energy for their functioning? Cells get energy for their metabolic reactions from the breaking of organic molecules with high energetic content. This energy

Complications during angina pectoris, Q. Complications during angina pector...

Q. Complications during angina pectoris? It is a symptom giving a warning of impending myocardial infarction, sudden cardiac death or even ischemic necrosis of the brain leadin

Define sit and reach flexibility component in the humans, Define Sit and Re...

Define Sit and Reach Flexibility component in the humans? The subject sits on a mat with legs extended straight ahead. Legs should be at right angles to a taped the r box, with

Dissolved oxygen - aquatic habitats, Dissolved oxygen - Aquatic Habitats ...

Dissolved oxygen - Aquatic Habitats Oxygen in the terrestrial ecosystems occurs in the atmosphere along with other gases in a certain fixed concentration however, in aquatic e

Define about the carbohydrates, Define about the Carbohydrates? In the ...

Define about the Carbohydrates? In the previous unit we have studied about the energy requirements. You now know that energy must be supplied regularly to individuals through t

Describe the theory of darwins, Describe the theory of Darwin's? Most s...

Describe the theory of Darwin's? Most scientists today accept the theory that living organisms have evolved according to the concept that was first proposed by Charles Darwin i

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