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

What are the kinds of reproduction that occur in fungi, Q What are the kind...

Q What are the kinds of reproduction that occur in fungi? In fungi there is sexual and asexual reproduction. Fungi reproduce asexually by fragmentation, sporulation and gemmati

What are some prophylactic measures for tapeworm infections, What are some ...

What are some prophylactic measures for tapeworm infections? The main prophylactic measures against taeniasis and cysticercosis are: not to ingest raw or badly cooked swine or

Encystment – protozoan, Encystment – Protozoan Encystment is character...

Encystment – Protozoan Encystment is characteristic of the life cycle of many protozoan. The protozoan secretes a thickened envelope (cyst) around itself and becomes inactive

Types of asexual reproduction, TYPES OF ASEXUAL REPRODUCTION ...

TYPES OF ASEXUAL REPRODUCTION 1 . Binar y fission - Amoeba 2. Multipl e fission -

What is suprasternal views in echocardiography, Q. What is Suprasternal Vie...

Q. What is Suprasternal Views in echocardiography? To complete the echocardiography in the patients with CHD these views are essential. For optimal windows patient should lie

Explain about the stilbenes, Explain about the Stilbenes? Stilbenes con...

Explain about the Stilbenes? Stilbenes contain 3 phenyl compounds connected by a 2-carbon methylene bridge and occur in nature in restricted distribution. In plants, they act a

Explain surlyn film, Q. Explain Surlyn film? Surlyn films: Surlyn (SU) ...

Q. Explain Surlyn film? Surlyn films: Surlyn (SU) is a versatile film which is sometimes favoured over polyethylene due to some unique properties such as excellent moisture b

Water loss - plant water relation, Water Loss - Plant Water Relation ...

Water Loss - Plant Water Relation Plants lose about 98% of water to the atmosphere by transpiration. Often water loss by transpiration exceeds gain by absorption and results

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