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

Fibroblast, Fibroblast  is the term applied to a cell of connective tissue ...

Fibroblast  is the term applied to a cell of connective tissue which is separated from similar cells by some degree of the matrix material; fibroblasts secrete elastin and collagen

phylum , characters of phylum rynchocephali

characters of phylum rynchocephalia

Chemical elements required for of living biological matter, Q. Which chemic...

Q. Which chemical elements are involved to form most of living biological matter? The chemical elements that form most of the molecules of living beings are carbon (C), oxygen

Syngamy and triple fusion, Syngamy and Triple Fusion After traversing...

Syngamy and Triple Fusion After traversing through the stylar region, the ultimate destination of the pollen tube is to reach the female gametophyte and release the male game

Is there respiratory pigment in the annelid blood, Q. Is there respiratory ...

Q. Is there respiratory pigment in the annelid blood? The blood in beings of the phylum Annelida contains the respiratory pigment hemoglobin the same found in chordates and oth

Kingdom protista, what is the taxonomy of phylum sporoza?

what is the taxonomy of phylum sporoza?

Explain the mitotic prophase, Which of the following best explains what wou...

Which of the following best explains what would happen if recombination (crossing-over) happens during mitotic prophase? A. Recombination during mitosis will lead to segregatio

Dispersal of seeds , Dispersal of Seeds A plant usually bears many fr...

Dispersal of Seeds A plant usually bears many fruits and innumerable seeds. If all the seeds produced by a plant were to germinate in the immediate vicinity, this will have s

Power plants of the aerobic cells, Why can mitochondria be considered the p...

Why can mitochondria be considered the power plants of the aerobic cells? Ans) Mitochondria are the "power plants" of aerobic cells due to within them the final stages of the ce

Agro industrial-soaking, Soaking Soaking is an another inexpensive proc...

Soaking Soaking is an another inexpensive processing method, which does not require much technical know how, is commonly practiced for improving the palatability of chaffed cro

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