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

Cohesiveness and surface tension-properties of water, Cohesiveness and Surf...

Cohesiveness and Surface Tension Water flows freely, yet water molecules do not break apart. They cling together particularly to polar surfaces. Therefore, water can fill a tub

Explain anaplerotic reactions, Anaplerotic Reactions Anaplerotic  reac...

Anaplerotic Reactions Anaplerotic  reactions are  reactions  that  replenish the  intermediates of  citric acid cycle. The  special  enzymatic mechanisms  by  which  the  pool

Explain some precautions for preparation of chloride buffers, Explain some ...

Explain some Precautions for Preparation of Chloride Buffers? 1. Glass electrodes should always be before and after measuring pH with a tissue paper. 2. The pipettes should

Nutrition, Nutrition, Feeding, Digestion All organisms require a fairl...

Nutrition, Feeding, Digestion All organisms require a fairly steady supply of nutrient materials from the environment to obtain energy in order to stay alive. The animals are

Patient after cardiac transplant, Patient after cardiac transplant ...

Patient after cardiac transplant The major focus of medical and nursing care after transplantation is to prevent early identification of rejection so that appropriate

What is the energy source used in active transport, What is the energy sour...

What is the energy source used in active transport through biological membranes? The energy essential for active transport (against the concentration gradient of the transporte

PROTOZOA, WHAT IS THE CLASSIFICATION OF PROTOZOA ..

WHAT IS THE CLASSIFICATION OF PROTOZOA ..

Point out some guidelines for breast-feeding, Point out some Guidelines for...

Point out some Guidelines for breast-feeding? 1) Follow demand feeding of the baby instead of a fixed schedule. 2) Initiate breast-feeding within 2 h after a normal delivery

Emf, In a neuron with a resting potential of -65 mV, the distribution of wh...

In a neuron with a resting potential of -65 mV, the distribution of which ion across the neuronal membrane represents the greatest potential electromotive force (EMF)? A. Potassiu

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