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

Leukamia.., is the leukamia dangerous

is the leukamia dangerous

Define regulation of water balance, Define Regulation of Water Balance? ...

Define Regulation of Water Balance? The input of water, as well as, its loss can be highly variable due to individual habits and environmental factors; in spite of this, the to

Tracheoles - respiration, Tracheoles - Respiration The tracheal syste...

Tracheoles - Respiration The tracheal system consists of an air filled system of tubes - the tracheal tubes that branch repeatedly until they become fine as capillaries, and

Define the open loop system, Situation in which a closed loop negative feed...

Situation in which a closed loop negative feedback system is  converted to an open loop system?     A.  A disease that destroys all the adenylyl cyclase and all the cAMP in the

Optical rotation in organice compounds, how the optical rotaion occurs in g...

how the optical rotaion occurs in glucose and ribose?

Mode of nutrition , What is the mode of nutrition in fish,human,amoeba,scor...

What is the mode of nutrition in fish,human,amoeba,scorpian & toad ?

Transcription of a eukaryotic protein-coding gene, 1. Describe how the vari...

1. Describe how the various molecular mechanisms act to regulate transcription of the genes within the lactose operon of E. coli . 2. Transcription of a eukaryotic protein-codi

Determine the concept of digestion of fats, Which of the following assist i...

Which of the following assist in the digestion of fats? A. Production of bile salts in the liver and the secretion of those bile salts into the small intestine. B. Emulsific

Active listening - counselling skills used in diabetes, Q. Active Listening...

Q. Active Listening - counselling skills used in diabetes? Every day we listen to many things, may be not with any intention or paying attention to the words, speech etc. For i

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