Hydra – metazoa, Biology

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.

Posted Date: 1/15/2013 2:06:37 AM | Location : United States







Related Discussions:- Hydra – metazoa, Assignment Help, Ask Question on Hydra – metazoa, Get Answer, Expert's Help, Hydra – metazoa Discussions

Write discussion on Hydra – metazoa
Your posts are moderated
Related Questions
Planning of Nursing Care   The goals of nursing care are:  Administer oral iron supplements and parenteral iron therapy.  Provide nutritional counselling and educate t


Metals and Alloys in alloplastic implant materials Most of the dental implant systems are made of metals or their alloys. Currently commercially pure titanium and its alloy Ti-

Pseudorabies Pseudorabies is a viral disease caused by pseudorabies virus (PRV) that is classified under family Herpesviridae. This disease is also known as “Aujeszky’s diseas

Eutrophication - Effect on Water Bodies Moderate quantities of sewage decay naturally in a water body and water gets purified after some time. But the problem arises when the

wht is the main quality of this phylum

Explain  the Techniques of Surgical Correction ? Techniques of Surgical Correction proximal Dissection (De Bakey type I and IZ or Stanford A) Monitoring lines are insert

Q. What are the modes of transmission, main signs and symptoms and treatments of hepatitis C? The Hepatitis C is caused by the RNA virus and transmitted through blood (like hep

T h e i l e r io s i s It is also referred as tropical theileriosis and results in fever, enlargement of superficial lymphnodes, anaemia and jaundice. E tiolo

what is reproductive system? what is urinary System? What is Nervous system