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

Indicators of disability burden: qalys/dalys, Normal 0 false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Atoms, the mass number is used to calculate the number of _________in one a...

the mass number is used to calculate the number of _________in one atom of an elemement. In order to calculate the number of neutrons you must subtract the _______from the ______.

Explain glycolysis, Explain glycolysis? Name the two monosaccharides w...

Explain glycolysis? Name the two monosaccharides which readily enter the glycolytic pathway. Illustrate a diagrammatic sketch of the microscopic view of a mammalian sperm a

Animal Respiration, What type of respiration does earthworm has ? In many c...

What type of respiration does earthworm has ? In many complex animals, the cells of internal organs are distant from the outside environment; respiratory systems provide the passag

Visceral larva migrans, Visceral larva migrans Visceral larva migrans,...

Visceral larva migrans Visceral larva migrans, also known as larval granulomatosis, is a clinical syndrome produced by the extra-intestinal migration of larval nematodes and i

How sex chromosomes of the xy system -sex determination, Concerning the sex...

Concerning the sex chromosomes of the XY system which type of gamete do the male and the female individuals respectively produce? An Individual of the female sex is XX and thus

Meiosis, MEIOSIS Every  organism is mortal, It  becomes  old and wornou...

MEIOSIS Every  organism is mortal, It  becomes  old and wornout  with advancing age  (= ageing )  and ultimately dies ,Before  death   however  ,it reproduces its own  kind, so

Explain the fermentability or degradability, Explain the Fermentability or ...

Explain the Fermentability or Degradability? As you are aware that colon contains over 400 known species of bacteria that exist in a symbiotic relationship with the host. All f

Zoology, right classification of protozoa up to class

right classification of protozoa up to class

Infective endocarditis, Infective Endocarditis   It  is a term used to ...

Infective Endocarditis   It  is a term used to include subacute bacterial endocarditis as well as infection caused by viruses  and fungi.  The causative organisms responsibl

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