It's sad to think that one day, the planet Earth may be gone.  This is despite our best efforts to save her. The good news is that provided we all work together, we can preserve the status quo on our beautiful blue world, for centuries to come.  Provided that is we heed the warnings nature is sending us, such as global warming and other pollutions.

CONSERVATION

Dramatic declines in amphibian populations, including population crashes and mass localized extinction, have been noted since the late 1980s from locations all over the world, and amphibian declines are thus perceived to be one of the most critical threats to global biodiversity. In 2004, the International Union for Conservation of Nature (IUCN) reported stating that currently birds, mammals, and amphibians extinction rates were at minimum 48 times greater than natural extinction rates - possibly 1,024 times higher. In 2006, there were believed to be 4,035 species of amphibians that depended on water at some stage during their life cycle. Of these, 1,356 (33.6%) were considered to be threatened and this figure is likely to be an underestimate because it excludes 1,427 species for which there was insufficient data to assess their status. A number of causes are believed to be involved, including habitat destruction and modification, over-exploitation, pollution, introduced species, global warming, endocrine-disrupting pollutants, destruction of the ozone layer (ultraviolet radiation has shown to be especially damaging to the skin, eyes, and eggs of amphibians), and diseases like chytridiomycosis. However, many of the causes of amphibian declines are still poorly understood, and are a topic of ongoing discussion.

POLLUTION AND PESTICIDES

The decline in amphibian and reptile populations has led to an awareness of the effects of pesticides on reptiles and amphibians. In the past, the argument that amphibians or reptiles were more susceptible to any chemical contamination than any land aquatic vertebrate was not supported by research until recently. Amphibians and reptiles have complex life cycles, live in different climate and ecological zones, and are more vulnerable to chemical exposure. Certain pesticides, such as organophosphates, neonicotinoids, and carbamates, react via cholinesterase inhibition. Cholinesterase is an enzyme that causes the hydrolysis of acetylcholine, an excitatory neurotransmitter that is abundant in the nervous system. AChE inhibitors are either reversible or irreversible, and carbamates are safer than organophosphorus insecticides, which are more likely to cause cholinergic poisoning. Reptile exposure to an AChE inhibitory pesticide may result in disruption of neural function in reptiles. The buildup of these inhibitory effects on motor performance, such as food consumption and other activities.

PROTECTION STRATEGIES

The Amphibian Specialist Group of the IUCN is spearheading efforts to implement a comprehensive global strategy for amphibian conservation. Amphibian Ark is an organization that was formed to implement the ex-situ conservation recommendations of this plan, and they have been working with zoos and aquaria around the world, encouraging them to create assurance colonies of threatened amphibians. One such project is the Panama Amphibian Rescue and Conservation Project that built on existing conservation efforts in Panama to create a country-wide response to the threat of chytridiomycosis.

Another measure would be to stop exploitation of frogs for human consumption. In the Middle East, a growing appetite for eating frog legs and the consequent gathering of them for food was already linked to an increase in mosquitoes and thus has direct consequences for human health.

Let the animals enjoy the Earth

Like birds, reptiles, mammals, and fishes, amphibians are vertebrates – that is, creatures with a backbone and an internal skeleton. Amphibians live part of their life in water and part on land. Even those species that lay eggs on land start life in a fluid-filled egg, breathing through gills.

AMPHIBIANS:

Bullfrog*
White's Tree Frog*

Amphibians (class Amphibia) are a group of animals that include all tetrapods (four-legged vertebrates) that do not have amniotic eggs. Amphibians (from Greek amphis "both" and bios "life") generally spend part of their time on land, but they do not have the adaptations to an entirely terrestrial existence found in most other modern tetrapods (amniotes). There are about 5,700 living species of amphibians.

History of amphibians

Amphibians developed with the characteristics of pharyngeal slits/gills, a dorsal nerve cord, a notochord, and a post-anal tail at different stages of their life. They have persisted since the dawn of tetrapods 390 million years ago in the Devonian period, when they were the first four-legged animals to develop lungs. During the following Carboniferous period they also developed the ability to walk on land to avoid aquatic competition and predation while allowing them to travel from water source to water source. As a group they maintained the status of the dominant animal for nearly 75 million years. 

Throughout their history they have ranged in size from the 15 foot long Devonian Ichthyostega, to the slightly smaller 6 foot long Eryops, and down to the tiny 1 centimeter long Psyllophryne didactyla, commonly known as the Brazilian Gold Frog. Amphibians have mastered almost every climate on earth from the hottest deserts to the frozen arctic, and have adapted to climatic change with ease.

• Solomon Berg Martin, Biology

• Duellman/Trueb, Biology of Amphibians

Frogs movie trailer

Classification

Traditionally the amphibians are taken to include all tetrapods that are not amniotes. Recent amphibians all belong to a single subgroup of these, called the Lissamphibia. Recently there has been a tendency to restrict the class Amphibia to the Lissamphibia, i.e. to exclude tetrapods that are not more closely related to modern forms than they are to modern reptiles, birds, and mammals.

There are two ancient, extinct, subclasses:

• Subclass Labyrinthodontia

• Subclass Lepospondyli

Of the remaining modern subclass Lissamphibia there are three orders:

• Order Anura (frogs and toads) (in Superorder Salientia): 5,070 species

• Order Caudata or Urodela (salamanders): 510 species

• Order Gymnophiona or Apoda (caecilians): 170 species

Authorities disagree on whether Salientia is a Superorder that includes the order Anura, or whether Anura is a sub-order of the order Salientia. In effect Salientia includes all the Anura plus a single Triassic proto-frog species, Triadobatrachus massinoti. Practical considerations seem to favour using the former arrangement now.

Frogs on the edge

Reproduction

For the purpose of reproduction all amphibians are bound to water. Several species have adapted to arid and semi-arid environments, but most of them need water to lay their eggs. The larvae breathe with exterior gills. After hatching they start to transform gradually to the adult's appearance. This process is called metamorphosis. Typically, the animals then leave the water and become terrestrial adults, but there are some exceptions to this general way of reproduction.

The most obvious part of the amphibian metamorphosis is the formation of four legs in order to support the body on land. But there are several other changes:

• The gills are replaced by other respiratory organs, e.g. lungs.

• The skin changes and develops glands to avoid dehydration

• The eyes get eyelids and adapt to vision outside the water

• An eardrum is developed to lock the middle ear

Select a species to find out more:

Iguana facts

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