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In Amphibians, such as Frogs, Metamorphosis is part of the life cycle. The gelatinous egg is fertilized externally in the water and develops in the pond. When it hatches, the tadpole emerges. What is interesting about a tadpole is that its diet is different than the adult frog. It is an herbivore and it eats mainly algae. It has gills and a streamlined body like a fish. It is aquatic at this point in its development. As it develops, the tail eventually disappears and the gills are replaced by simple sac-like lungs. Hormones regulate the process of metamorphosis in Amphibians, much like the way hormones cause puberty to occur in humans! The adult frog has limbs which develop and its strong back legs are adapted to jumping and moving about on land. They also have a different diet and as adults are carnivores eating mainly insects. To summarize, metamorphosis is an important process in the life of Amphibians.
Yes, for most amphibians. Just think of frogs and toads. They begin their life as tadpoles adapted to life under water and then develop into frogs and toads that hop around on land and breathe air. During metamorphosis, tadpoles loose their external gills for breathing underwater and loose their tails for swimming. The tadpoles develop legs, a large jaw and a tongue. They also develop large eyes and their brain actually changes to be better able to use the new eyes. They further develop lungs, a skull of bone instead of cartilage, and other changes occur as well to their skin and ears. New hormones regulate the entire process. Many newts and salamanders also undergo metamorphosis, but not all. Amphibian metamorphosis does not have an inactive stage like the pupal stage of insects.
Let's decode your question: What is metamorphosis? What are amphibians? What is a key characteristic?
Metamorphosis is a change or transformation. Metamorphosis happens in amphibians and insects. It can be complete (think catepillar to butterfly) and incomplete (think the change from tadpole to frog).
Amphibians are frogs and toads. They spend part of their lives in the water and part out of the water.
A key characteristic is something that defines something or separates something in a group.
Lets put it together:
Is the fact that amphibians undergo metamorphosis as part of their lifecycle a key characteristic be them and other animals?
The answer is YES!
By definition, amphibian means two lives. It is a key characteristic that separates them from reptiles which do not change. Some amphibians do spend their whole life on land or in water, but they must always be near water or in humid moist habitats. All amphibians have gills when living underwater. Most amphibians lose their gills by the adult stage.
Metamorphosis means transformation. This term is used by biologists to describe the extreme changes in form and appearance that occur in lower animals between the growing phase of life and the mature adult phase.
In higher animals such as humans, cats, and cows, the difference in the young ones and the adults is mainly in the size. There is no major change in their form. But in some other animals major changes take place in the form during the growth of young ones to adulthood. Such changes or metamorphosis is most striking in the case of butterflies that pass through four stages of egg in embryo form, larva or
caterpillar, pupa and the adult.
Amphibians, such as frogs and toads, the fertilized egg does not contain enough nutrients for the offspring to develop completely by the time the egg hatches. As a result, an amphibian goes through a larval stage after it hatches and before it becomes an adult. During this stage, the animal gathers and eats the food needed to reach full maturity.
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