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

Explain gastrointestinal, Gastrointestinal Antibiotic prophylaxis is re...

Gastrointestinal Antibiotic prophylaxis is recommended for esophageal surgery in the presence of obstruction, which increases the risk of infection. After gas troduodenal surge

Protozoa, what is the life cycle of a protozoa

what is the life cycle of a protozoa

Lymph, why is it known as middle man

why is it known as middle man

Oxusome, structure of oxysome

structure of oxysome

What is the etiological agent of cutaneous leishmaniasis, Q. What is the et...

Q. What is the etiological agent of cutaneous leishmaniasis? How is the disease transmitted and what are its typical manifestations? The protozoan Leishmania braziliensis is et

Heat energy is liberated during respiration, Some amount of energy is gener...

Some amount of energy is generatred from the oxidation of food materials is released as heat. This can be proved by germinating seeds. Aim: To show that heat is liberated during re

Artificial selection, ARTIFICIA L SELECTION - Man selects the indiv...

ARTIFICIA L SELECTION - Man selects the individuals having the desired traits and separates them from those, which do not possess such characters. The selected ones are

Benefits of computerization, Benefits of Computerization Computerizati...

Benefits of Computerization Computerization were the following benefits in nursing: Improved professional care  Better accuracy (by decreasing human error)  Effect

What are the processes of the photochemical stage, What are the processes o...

What are the processes of the photochemical stage of the photosynthesis process? Photolysis of water, with liberation of molecular oxygen, and photophosphorylation of ADP, with

What is the coelom, What is the coelom? To which structures do coeloms give...

What is the coelom? To which structures do coeloms give birth? Are all animals coelomate? Coeloms are cavities delimited by mesoderm. Coeloms create the cavities where the inte

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