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Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods excluding the amniotes (tetrapods with an amniotic membrane , such as modern reptiles , birds and mammals ).
Start-Class amphibian and reptile articles of Low-importance (4,659 P) Start-Class amphibian and reptile articles of Mid-importance (376 P) Start-Class amphibian and reptile articles of NA-importance (empty)
Vertical product differentiation can be measured objectively by a consumer. For example, when comparing two similar products, the quality and price can clearly be identified and ranked by the customer. If both A and B products have the same price to the consumer, then the market share for each one will be positive, according to the Hotelling ...
Niche models are a notable class of CRMs which are described by the system of coupled ordinary differential equations, [7] [8] = (), =, …,, = + = (), =, …,, where (, …,) is a vector abbreviation for resource abundances, is the per-capita growth rate of species , is the growth rate of species in the absence of consumption, and is the rate per unit species population that species depletes ...
This would help account for the relative scarcity of amphibian fossils from the period before the groups split. [24] Another molecular phylogenetic analysis conducted about the same time concluded that lissamphibians first appeared about 330 million years ago and that the temnospondyl-origin hypothesis is more credible than other theories.
It is crucial for most amphibians to maintain a high level of genetic variation through large and more diverse environments. Education of local people to protect amphibians is crucial, along with legislation for local protection and limiting the use of toxic chemicals, including some fertilizers and pesticides in sensitive amphibian areas. [53]
Caecilians have small or absent eyes, with only a single known class of photoreceptors, and their vision is limited to dark-light perception. [17] [18] Unlike other modern amphibians (frogs and salamanders) the skull is compact and solid, with few large openings between plate-like cranial bones. The snout is pointed and bullet-shaped, used to ...
Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia . They inhabit a wide variety of habitats , with most species living within terrestrial , fossorial , arboreal or freshwater aquatic ecosystems .