Metamorphosis in amphibians, Biology

Metamorphosis in Amphibians

Metamorphosis is radical in anurans, slight or not exists in urodeles. In anuran amphibians like toads and most frogs, metamorphosis is generally associated with a transition from an aquatic to a terrestrial or amphibious mode of life. Occasionally though no transition in mode of life takes place as observed in the larval and adult of the frog Xenopus laevis and many primitive anurans that remain aquatic throughout their life. The change in habitat in the frogs and toads also generally results in a change in their feeding habit. In some like X laevis there is no change in food habit because both larvae and adult ale carnivorous. Some anurans go through an abbreviated type of metamorphosis before hatching, as they pass through a tailed, gilled tadpole-like stage within the jelly membrane of the egg. Others go through direct development by skipping the larval stages totally.

Metamorphosis in urodele amphibians is generally less striking. Some of them undergo direct development, while others fail to complete their metamorphosis. The latter acquire sexual maturity as larvae, as seen in the axolotl larvae of Ambystoma. This phenomenon is termed as neoteny. Some urodeles like salamanders have been observed to go through two metamorphosis. Metamorphosis in both anurans and urodeles essentially includes the activation of the genomic set underlying the adult organization, which needs for its expression a minimum mass of tissue i.e. greater than that of the egg. The activation is believed to be due to the secretion of a brain hormone that initiates metamorphosis. The hormone triggers the degeneration of redundant larval organs and growth of hitherto quiescent structures that are needed in the adult. In amphibians the process of destruction and growth are smoothly coordinated, as a result of which the animal retains its functional integrity throughout metamorphosis in place of lying dormant as in the case of insects.

Posted Date: 1/30/2013 5:57:50 AM | Location : United States

Related Discussions:- Metamorphosis in amphibians, Assignment Help, Ask Question on Metamorphosis in amphibians, Get Answer, Expert's Help, Metamorphosis in amphibians Discussions

Write discussion on Metamorphosis in amphibians
Your posts are moderated
Related Questions
>>>>Write a short note on the following- Question 1 Centrism in Bioethics Question 2 Bio Safety check list Question 3 Enforcement of IPRs Question 4 T

Describe normal regulation of blood glucose via the pancreatic hormones. How is this altered with Diabetes? Why is Diabetes called an impairment to the homeostasis of glucose? What

PHYSICAL STATE OF PROTOPLASM Several theories have been given about its physical structure - (i )  Granular Theory (Proposed by Altman, Hanstein, 1886) - Granules embed

Define Oral rehydration for treatment for pem? Since diarrhoea is very common in severe PEM, correction of dehydration is the first step in the treatment. Homemade (salt-sugar

Polymorphism in Lysosomes Polymorphism, i.e. existence of a structure in more than one form, is an important feature of lysosomes. Several different forms of lysosomes have been

write breif notes on oogenesis

Natural selection can therefore mean differential reproduction among members of the sarne gene pool. We earlier said that selection would promote those alleles that give rise to ph

Determine uses of Soybean protein? Soybean protein concentrates have been used as stabilized dispersions in milk- like beverages and simulated dairy products, such as sour crea

Explain about the Nutritional recommendations for Healthy Ageing? You would recall reading about meal planning during various stages of life, spanning right from the infancy ti

commercially important bivalve species