Radial and biradial - metazoa, Biology

Radial and Biradial-Metazoa

Radial symmetry is the symmetry in which the parts are so arranged around a central axis or shaft, like the spokes of a wheel, that any vertical cut through the axis would divide the whole animal into two identical halves. The common jelly fish and hydra (cnidaria) - exhibit radial symmetry. The starfish and their relatives have a modified form of radial symmetry. They can be divided along 5 planes, each giving two distinct halves. This is known as pentermerous symmetry.

One side of the body has the mouth and is known as the oral surface; the opposite side is aboral. Cuts made along the oral-aboral axis will result in identical halves. Biradial symmetry is a variant of this and it is found in sea anemones and ctenophores. Though the animal appears to be radially symmetrical, it can be divided only into two equal halves along two per-radial positions - along the tenticular plane and along the sagittal plane at right angles to it. Radial and biradial animals are usually sessile, floating freely or weak swimmers. These animals are called the Radiata.

Posted Date: 1/15/2013 1:36:16 AM | Location : United States







Related Discussions:- Radial and biradial - metazoa, Assignment Help, Ask Question on Radial and biradial - metazoa, Get Answer, Expert's Help, Radial and biradial - metazoa Discussions

Write discussion on Radial and biradial - metazoa
Your posts are moderated
Related Questions
Necessity of interdependence of Volvox organisms in the colonial existence

A mother has brought her 2-week-old infant to the emergency department due to the baby's persistent and increasing jaundice. Blood testing reveals that the infant's unconjugated bi

Define Precaution for Separation of Amino Acids by Paper Chromatography? 1. Hold the paper with the extra strip kept at one side. Handling of whatman paper with hand should be

GENERA L MECHANISM OF BLOOD COAGULATION - All researchers agree that blood clotting is a cascade mechanism and involves three essential steps - (a) Formation of prothrombin ac

Mature Embryo A typical dicotyledonous embryo, as seen in a median longitudinal section, consists of an embryonal axis having two broad cotyledons. The portion of embryonal ax

Define Dietary Goals in Parkinson's Disease? The main goals include: - Maintain desirable weight - Promote absorption of anti- Parkinson's drug levodopa - Lessen swall

Define isolated soybean proteins in Cereal products? ISP is sometimes used instead of, or in combination with isolates and soy flour, in the formulation of milk replacer mixtur

In which type of animals does the placenta exist? What is its main function? True placenta is present in placental mammals. The placenta is produced from the chorion of the

Explain about lyophilic If the affinity between the dispersed phase and the medium is high, the dispersed phase is said to be lyophilic (solvent loving) or hydrophilic, in the