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

Benefits of haccp, The benefits of HACCP  can be  summarized  as under. ...

The benefits of HACCP  can be  summarized  as under. a)  Benefits to Consumers Reduced risk of food borne diseases Increased confidence in food supply Increased awar

Explain linolenic acids, Linolenic Acids Fats in this group contain sub...

Linolenic Acids Fats in this group contain substantial amounts of linolenic acid (C18 triunsaturated). Examples are soybean, mustard, rapeseed, flaxseed and wheat germ hemps

Define interaction of niacin with other nutrients, Define Interaction of ...

Define Interaction of niacin with other Nutrients? You may recall reading earlier that trypotophan present in dietary proteins is converted to niacin. There is an interdepend

Explain about the transcellular route - calcium, Explain about the Transcel...

Explain about the Transcellular Route - Calcium? Transcellular Route: It operates primarily in the duodenum and proximal jejunum. It is stimulated when Ca ingestion is lower re

425, #questionThree actographs (look closely to see the labels A, B, and C)...

#questionThree actographs (look closely to see the labels A, B, and C). Assume that the abscissa is either 24 or 48 hours for each actograph. You are asked to write two sentences f

Name of structures you would expect to find in the dermis, Name of the stru...

Name of the structures you would expect to find in the dermis. In the dermis you would expect to search sensory nerve endings, nerve fibres, capillaries, arterioles and venules

Cell - basic unit of life, Cell - Cell is the structural & functiona...

Cell - Cell is the structural & functional unit of life. Study of the structure of the cell is called cytology. Study of structure and functions of the cell is called

Define hydroxybenzoic acid and hydroxycinnamic acid, Define Hydroxybenzoic ...

Define Hydroxybenzoic acid and Hydroxycinnamic acid? Hydroxybenzoic acid: e.g. ellagic and gallic acids, which are hydrolyzable tannins, present in berries and nuts. Hydroxy

Cell theory, what year did virchow state where a cell exists there must hav...

what year did virchow state where a cell exists there must have been a pre-existing cell

Function of lipids, FUNCTIO N OF LIPIDS Fats are storage products ...

FUNCTIO N OF LIPIDS Fats are storage products of both plants and animals. I n plants , fats are commonly stored in spores and seeds while in animals they are sto

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