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

Define about the classification of polyphenols, Define about the Classifica...

Define about the Classification of polyphenols?  The various classes are: a) Phenolic acids and derivatives b) Flavonoids such as Flavonols and Flavones, Isoflavones and

Interventricular septum, It corresponds to the anterior and inferior interv...

It corresponds to the anterior and inferior interventricular grooves. Its right side is convex and bulges to the right ventricle. The septum has a posterior border which separates

List a few applications of starches in the food industry, List a few applic...

List a few applications of starches in the food industry. A few applications of starches in the foods industry include thickener, a fat sparing agent, adhesive, binder,

Define corneal ulcer - micronutrient deficiencies, Define Corneal Ulcer - M...

Define Corneal Ulcer - Micronutrient Deficiencies? Corneal xerosis, if not treated promptly, leads to ulceration of the cornea. Initially, the ulcer may be shallow, and if it b

What is blood typing?, What is blood typing? The Blood typing is the de...

What is blood typing? The Blood typing is the determination, by means of tests, of the classification of a blood sample concerning blood group systems (specially the Rh system

Prothoracic gland or ptc, Prothoracic Gland or PTC Prothoracic gland ...

Prothoracic Gland or PTC Prothoracic gland (PTC) or moulting gland and ecdysone or moulting hormone The 3 rd endocrine gland-prothoracic gland- is an irregular branching

Explain resistance to isoniazid, Resistance to Isoniazid  The most comm...

Resistance to Isoniazid  The most common pattern of resistance is isolated resistance to isoniazid, which can be treated with rifampin, pyrazinamide and ethambutol for 6-9 mont

Organ that belongs to more than one organ system, What is an organ that bel...

What is an organ that belongs to more than one organ system? One answer is the pancreas. It belongs to both the endocrine and digestive systems. Another one is bone marrow. It

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

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