Hydra – metazoa, Biology

Assignment Help:

Hydra – Metazoa

The animals of phyla Cnidaria and Ctenophora are made up of only two germ layers: ectoderm which forms the outer covering of the animal and endoderm which is the inner layer and is also known as the gastroderm. However, a non-cellular jelly like substance mesoglea is present between ectoderm and endoderm which acts as a cement to bind the two layers. This layer should not be confused with the third germ layer i.e. mesoderm. Since animals of these two phyla do not have mesoderm, they are said to be diploblastic.

2474_Hydra – Metazoa.png

Figure: L.S. Hydra

If we cut a longitudinal section through 'Hydra we see two distinct layers bound together by a non-cellular mesoglea. The two germ layers give rise to many different cell types - as evident from figure. Rest of the animals (platyhelminths to mammals) are all made up of three germ layers viz. ectoderm, endoderm and mesoderm. These animals are triploblastic. If we cut a section say through a horse (a mammal and triploblastic) can we expect to see three layers like you see two layers in diploblastic Hydra? No we will net, because these three germ layers do not .remain as such, they differentiate and modify to give rise to different structures and organs in the body of the horse. The three layers will be distinct only during early embryology. Hence we call them the embryonic layers or the germ layers.


Related Discussions:- Hydra – metazoa

Historically how the origin of life on earth been explained, Historically h...

Historically how has the origin of life on earth been explained? The mainly recurrent explanation for the phenomenon of life on earth is the mythological. The People from vario

How will this increase survival, Why would we evolve so that when we are st...

Why would we evolve so that when we are stressed our immune system is suppressed? How would this increase survival?

Shifting cultivation - degradation of ecosystem, Shifting cultivation - Deg...

Shifting cultivation - Degradation of Ecosystem This method of cultivation is practised all over the globe, but is more prevalent in the tropical countries. In this practice a

Explain the major classes of lipids, Explain the major classes of lipids ...

Explain the major classes of lipids The major classes of lipids are simple lipids (acylglycerols and waxes); Compound lipids (glycerophospholipids); Derived lipids (compounds t

Define interaction of vitamin c with other vitamins, Define Interaction of ...

Define Interaction of Vitamin C with other vitamins? a. Ascorbic acid and other vitamins: Ascorbic acid synthesis is diminished in thiamin and riboflavin deficiency. Vitamin

Illustrate stage of cellular respiration, Q. What is the stage of cellular ...

Q. What is the stage of cellular respiration during which carbon dioxide is liberated? In aerobic cellular respiration the release of carbon dioxide happens in the transformati

Supplementation to prevention of iron deficiency anaemia, Define Supplement...

Define Supplementation to prevention of iron deficiency anaemia? Supplementation with low doses of iron is necessary to prevent anaemia in particular groups of people. Fortifie

T or F, The role of ATP hydrolysis in actin polymerization is similar to th...

The role of ATP hydrolysis in actin polymerization is similar to the role of GTP hydrolysis in tubulin polymerization: both serve to weaken the bounds in the polymer and thereby pr

Explain obsessive-compulsive disorder, a) Explain obsessive-compulsive diso...

a) Explain obsessive-compulsive disorder? How is it dissimilar from borderline personality disorder? What are the two most common obsessions that affect adolescents?

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