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

What are the different organ of the gastrointestinal system, The different ...

The different organs of the gastrointestinal system  Mouth or buccal cavity - Teeth 32 Permanent and - Tongue  Pharynx  Oesophagus  Stomach  Small Intestine

Explain in detail about soil micromorphology, Explain in detail about soil ...

Explain in detail about soil micromorphology A good examination with optical aid reveals more detailed features which are helpful in understanding pedogenesis. This is known as

Transport of oxaloacetate, Pyruvate   carboxylase   is a mitochondrial   ma...

Pyruvate   carboxylase   is a mitochondrial   matrix enzyme whereas the other enzymes of gluconeogenesis are situated outside the mitochondrion. Thus oxaloacetate are produced by p

Stages of wilms tumour , Stages of Wilm's tumour  We shall now discuss...

Stages of Wilm's tumour  We shall now discuss about the various stages of Wilm's tumour. The extent of  disease is staged according to the findings of  surgery and  the presen

Define about the calcium - macro minerals, Define about the Calcium - Macro...

Define about the Calcium - Macro minerals? Among minerals, calcium (Ca) is the most abundantly present in humans, representing 52% of the body's mineral content and amounting t

Difference between the concepts of food chain and food web, What is the dif...

What is the difference between the concepts of food chain and food web? The chain theory is a theoretical model to study the energy flux in ecosystems. In fact, in an ecosystem

Agro industrial-mineral supplements, Mineral supplements There are two...

Mineral supplements There are two major classes of mineral sources: inorganic and organic. Organic complexes, however, have been shown to be more effectively absorbed by the a

Determine the functional food in europe, Determine the Functional Food in E...

Determine the Functional Food in Europe? Functional foods are: Conventional/everyday foods consumed as a part of the normal diet; Composed of naturally-occurring co

Can you explain yersinia enterocolitica gastroenteritis, Q. Can you explain...

Q. Can you explain Yersinia Enterocolitica Gastroenteritis? Yersiniosis is an infectious disease caused by a bacterium of the genus Yersinia. Most human illness is caus

Is water a polar or a non-polar molecule, Is water a polar or a non-polar m...

Is water a polar or a non-polar molecule? What is the consequence of that characteristic for the function of water as solvent? Water is made of two atoms of hydrogen attached b

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