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

Acute complications of ptca, Acute Complications of PTCA :  The incide...

Acute Complications of PTCA :  The incidence of complications after PTCA that require emergency surgery has reduced considerably in the present era. Introduction of stents, pe

Bovine rotavirus diarrhoea, B o v i ne rotavirus diarrhoea The bovi...

B o v i ne rotavirus diarrhoea The bovine rotavirus is a RNA virus with 11 segments of double stranded RNA belonging to the genus Rotavirus in the family Reoviridae. Rotavi

What is class gastropoda in animal kingdom, What is Class Gastropoda in ani...

What is Class Gastropoda in animal kingdom? Snails and slugs are referred to as gastropods because of their characteristic body plan. "Gastro" is derived from the Greek word fo

Define objectives to know about methods of food processing, Define Objectiv...

Define Objectives to know about methods of food processing? After studying this unit, you will be able to: Enumerate the different methods of food processing Enlist

Describe the plasma membrane of the beta-islet cell, Insulin binding to ins...

Insulin binding to insulin receptors in the plasma membrane of a A. liver cell will lead to an enhance in the intracellular amounts of cAMP in the liver cell. B. beta-islet

Explain what is molds , Explain what is Molds ? Zygomycota, or molds, a...

Explain what is Molds ? Zygomycota, or molds, are a type of fungus made of filamentous hyphae that grow on decomposing material. The molds actually aid in the decomposition pro

Agro industrial-processing of roughage, Processing of roughage Roughag...

Processing of roughage Roughages constitute the bulk of the ration of farm animals and these include green fodder (leguminous and non-leguminous), grasses, and various crop re

What are dna ligases, What are DNA ligases? How do these enzymes participat...

What are DNA ligases? How do these enzymes participate in the recombinant DNA technology? The DNA ligases are enzymes specialized in tying the complementary DNA chains that for

Adrenaline and noradrenaline, Both these neurotransmitter strengthen memory...

Both these neurotransmitter strengthen memory when they are released into the blood stream following learning. Stressful events stimulate release of stress hormones from the adrena

Pelagic zone - organisation of the marine ecosystem, Pelagic Zone - Organis...

Pelagic Zone - Organisation of the Marine Ecosystem The waters contained in the sea basin, constitute the pelagic zone which is divided into The neritic zone situ

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