Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
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.
Define the Redia Larva? Redia is the third larval stage in the life cycle of F. heputicn. Redia develops from the germ cell Is of the sporocyst and comes out of the sporoc
What is peristomium. Describe? The segment behind the prostomium in annelids which contains the oral opening. This segment like the prostomium isn't a true segment and has no s
Q. Concerning volition of the individual how can the reactions of the nervous system be classified? The efferences (reactions) of the nervous system can be classified into volu
A friend of yours suggests that the origin of life on earth is extraterrestrial in origin (an idea known as panspermia). Can you propose a testable hypothesis to determine if this
Q. What is facial prosthesis? Dental implants have prosthesis also been used for facial prosthesis which includes nasal, orbital or auricular prosthesis. Implant and bar retain
Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4
What is Phylum Hemichordata ? The name "hemi"; (meaning "half") provides a clue to these animals, which have some of the features of chordates, and some features that are chara
What are the disadvantages of protozoa
Why is the cerebellum more developed in mammals that jump or fly? The cerebellum is the major brain structure that coordinates the movement and the equilibrium of the body. For
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd