Hydra – metazoa, Biology

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.

Posted Date: 1/15/2013 2:06:37 AM | Location : United States







Related Discussions:- Hydra – metazoa, Assignment Help, Ask Question on Hydra – metazoa, Get Answer, Expert's Help, Hydra – metazoa Discussions

Write discussion on Hydra – metazoa
Your posts are moderated
Related Questions
Explain the Sedimentation - Air Sampling? It is the simplest method, which involves exposing agar plates in air for specified time at a location to be sampled.  Microorganisms

Diabetes mellitus, Types I and II is a disorder regarding the defects in insulin action. Type I diabetes is characterized by an inadequate insulin secretion; Type II diabetes is

Determine the different types of sensory receptors There are different types of sensory receptors as follows:  Visual receptors in the eyes for vision.  Auditory receptor

Comparison between Metamorphosis in Amphibians and Insects You may have realized that the metamorphic process in amphibians and insects show certain fundamental similarity. M

What is Excessive Fat Intake? Although minimum amount of fat is essential as calculated above but upper limit of fat should be drawn due to its link with an increased risk of d

A solid compound was found to contain 42.11% C, 51.46%O and 6.43% H by weight. The molecular weight of the compound was 341. What is the molecular formula of the compound?

Determine Fat Soluble Vitamin Needs of school children and adolescents? ICMR (1990) does not give recommendations for vitamin D, E and K. Vitamin D is very important for skelet

MR means medical representative. Medical rep has to sell products of pharma companies or drug manufacturers. He has to go to doctors and medical shops to sell drugs and promote dru

In patients who have not received prior antibiotics and who will ultimately have blood culture positive endocarditis, it is likely that 95 - 100 per cent of all cultures obtained w

why the small intestine is longer in herbivores as comparison to carnivores animals