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

What is the significance of axial skeleton, What is the significance of Axi...

What is the significance of Axial skeleton? The bones which make up skeleton of the main body axis of vertebrates. It comprise the cranium, vertebral column, and rib cages, How

What percentage of the offspring would be tall, Tall (T) plants are dominan...

Tall (T) plants are dominant and short (t) plants are recessive. Two heterozygous tall plants are crossed. What percentage of the offspring will be tall?

Define formation of healthy food habit - combat from obesity, Define Format...

Define Formation of healthy food habit - combat from obesity? Discarding faulty habits as early as possible. Most food habits formed at this age are for a life time. Special c

How to increase in the amount of glucokinase in liver, How to increase in ...

How to increase in  the amount of glucokinase in liver Consumption of a meal rich in carbohydrate  or administration  of insulin initiate an increase in  the amount of glucokin

Describe integrative systems of the body, Q. Why is the endocrine system co...

Q. Why is the endocrine system considered one of the integrative systems of the body? What is the other physiological system that also has this function? The endocrine system i

Types of fertilization, TYPES OF FERTILIZATION - On the basis of site o...

TYPES OF FERTILIZATION - On the basis of site of fertilization, it is of two types - 1. External fertilization        2. Internal fertilization 1 .       EXTERNAL FERTILIZ

Cockroach - tracheal system, can you give brief diagram of the tracheal sys...

can you give brief diagram of the tracheal system of cockroach?

How fats promote absorption of fat soluble vitamins, 1. Fats promote absorp...

1. Fats promote absorption of fat soluble vitamins like vitamin A, D, E and K. Patients of cystic fibrosis often absorb fat poorly and are at-risk for fat-soluble vitamin deficienc

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