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

The genetic code is degenerate, Because RNA is composed  of four parts of n...

Because RNA is composed  of four parts of nucleotides,  there are 43 =  64 possible codons,  which  is  64  possible  triplets  of  nucleotides   with  several  sequences. Furtherm

Explain the role of bones in human biology, Explain the role of Bones in hu...

Explain the role of Bones in human biology? Bone is covered by a tough outer membrane called the periosteum. The periosteum contains systems of capillaries that supply the bone

Nursing research, Definition: We  will  first define the term "Researc...

Definition: We  will  first define the term "Research" before  explaining the term Nursing Research. Research is a scientific process. It is defined as a systematic search for

How does hcl also directly participate in digestion, Besides being fundamen...

Besides being fundamental for the activation of the main gastric digestive enzyme how does HCl also directly participate in digestion? With its corrosive effect, HCl also helps

What do you mean by polyphagia, Q. What do you mean by Polyphagia? Incr...

Q. What do you mean by Polyphagia? Increased Hunger (Polyphagia): As patient is losing more sugar in the urine, he feels hungry very soon and tends to take more food. It is cal

Cardiac output and its determination, The cardiac output is the volume of b...

The cardiac output is the volume of blood pumped from the heart every minute. It is obtained by the volume pumped with each beat (stroke volume) multiplied by the heart rate. The c

Bio-informational homework, Determine sequence weights for the sequences AC...

Determine sequence weights for the sequences ACTA, ACTT, CGTT, and AGAT in problem 1 by using Thompson, Higgins, and Gibson method

Functions of cell wall, FUNCTIONS OF CELL WALL 1.       Provides shape ...

FUNCTIONS OF CELL WALL 1.       Provides shape to plant cell rigidity to cells. 2.       Functions as a barrier to entry of pathogens into the cells. 3.       Provides pr

What are the nucleic acids, Q. What are the nucleic acids? What is the hist...

Q. What are the nucleic acids? What is the historic origin of this name? RNA and DNA, the nucleic acids, are the molecules responsible for the hereditary information that comma

Explain spermatocyte I and spermatocyte II, What is the difference between...

What is the difference between spermatocyte I and spermatocyte II? The spermatocyte I (2n) undergoes the primary division of meiosis (meiosis I) originating two spermatocyte II

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