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

Describe the process of coronary atherosclerosis, Q. Describe the process o...

Q. Describe the process of coronary atherosclerosis? Atherosclerosis is an intimal disease of arteries ranging in size from the aorta to the epicardial coronary artery i.e. cha

What is diabetes mellitus, Question 1 What is diabetes mellitus? Discuss b...

Question 1 What is diabetes mellitus? Discuss briefly its pathogenesis. Explain how would you diagnose this disorder Question 2 Discuss the following Glucose tolerance

Viriods and prions, Viriods and Prions Viroids        In 1971, T.O...

Viriods and Prions Viroids        In 1971, T.O.Diener reported that the  spinde tuber disease of potato causing gnarling and cracking of the tuber, is caused by multiplica

Define factors that affect the requirement of protein, Define Factors that ...

Define Factors that affect the requirement of Protein? Protein requirement is greatly influenced by many factors such as age, environmental temperature, energy intake, gender,

What is prokaryotic chromosomes, The DNA of a bacterial cell,such as Escher...

The DNA of a bacterial cell,such as Escherichia coli is a circular double-stranded molecule  often  referred  to as the bacterial  chromosome.  The circular  DNA  is packaged into

Regulation of alkalinity and acidity of the plasma, Q. In which nephron por...

Q. In which nephron portion does the regulation of alkalinity and acidity of the plasma occur? The regulation of the acid-basic equilibrium of the body is done by the kidneys a

Source of cells for regeneration, Source of Cells for Regeneration It...

Source of Cells for Regeneration It had been considered earlier that interstitial cells constitute a reserve of undifferentiated cells that provide the cellular material for

How is striped pattern of the striated muscle cells formed, How is the stri...

How is the striped pattern of the striated muscle cells formed? The functional units of the muscle fibers are the sarcomeres. Within the sarcomeres blocks of myosin and actin

Explain procedure for acid fast staining, Explain Procedure for Acid Fast S...

Explain Procedure for Acid Fast Staining? Carry out the exercise using the steps enumerated herewith. 1. Label the clean, non-greasy slides and make smears of M. smegmatis,

Parasitic adoptaion in animal, #question.what do u mean by parasitic habit....

#question.what do u mean by parasitic habit.give account of various parasitic adoptation in animal.

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