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. All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura, Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems. Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically.
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch.
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches.
Darwin’s frog, also called the Southern Darwin's frog, is a species of Chilean/Argentinian frog of the family Rhinodermatidae. It was discovered by Charles Darwin during his voyage on HMS Beagle. on a trip to Chile. In 1841, French zoologist André Marie Constant Duméril and his assistant Gabriel Bibron described and named Darwin's frog. The diet of R. darwinii consists mostly of herbivore invertebrates. R. darwinii is currently classified as an endangered species by the International Union for Conservation of Nature.
Fish reproductive organs include testes and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused. There may also be a range of secondary organs that increase reproductive fitness. The genital papilla is a small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish can often be determined by the shape of its papilla.
A true toad is any member of the family Bufonidae, in the order Anura. This is the only family of anurans in which all members are known as toads, although some may be called frogs. The bufonids now comprise more than 35 genera, Bufo being the best known.
Nectophrynoides is a genus of true toads, family Bufonidae. They are endemic to Eastern Arc forests and wetlands in Tanzania, and all except N. tornieri are threatened. Species of the genus are ovoviviparous: fertilization is internal, and the females give birth to fully developed, small toadlets. Together with the West Africa Nimbaphrynoides and Limnonectes larvaepartus, they are the only frogs/toads in the world that do not lay eggs. The Ethiopian Altiphrynoides, which lay eggs, were also part of Nectophrynoides in the past.
Limnonectes is a genus of fork-tongued frogs of about 75 known species, but new ones are still being described occasionally. They are collectively known as fanged frogs because they tend to have unusually large teeth, which are small or absent in other frogs.
Rheobatrachus, whose members are known as the gastric-brooding frogs or platypus frogs, is a genus of extinct ground-dwelling frogs native to Queensland in eastern Australia. The genus consisted of only two species, the southern and northern gastric-brooding frogs, both of which became extinct in the mid-1980s. The genus is unique because it contains the only two known frog species that incubated the prejuvenile stages of their offspring in the stomach of the mother.
The vitelline membrane or vitelline envelope is a structure surrounding the outer surface of the plasma membrane of an ovum or, in some animals, the extracellular yolk and the oolemma. It is composed mostly of protein fibers, with protein receptors needed for sperm binding which, in turn, are bound to sperm plasma membrane receptors. The species-specificity between these receptors contributes to prevention of breeding between different species. It is called zona pellucida in mammals. Between the vitelline membrane and zona pellucida is a fluid-filled perivitelline space.
The plains spadefoot toad is a species of American spadefoot toad which ranges from southwestern Canada, throughout the Great Plains of the western United States, and into northern Mexico. Like other species of spadefoot toads, they get their name from a spade-like projection on their hind legs which allows them to dig into sandy soils. Their name, in part, comes from their keratinized metatarsals, which are wide instead of "sickle shaped". The species name translates as buzzing leaf shaped. This refers to the species' distinguishing features; its buzzing mating call, and its leaf-shaped digging metatarsals. It was first described by Cope in 1863.
Edalorhina perezi is a species of frog in the family Leptodactylidae. It is one of the only two species in the genus Edalorhina in the family Leptodactylidae. This species is diurnal and terrestrial. During mating season both female and male frogs gather around treefall pools. It is found in Brazil, Colombia, Ecuador, and Peru, and possibly Bolivia. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests, and freshwater marshes. The species listed as least concern on the IUCN Red List and the population is stable.
Stefania evansi is a species of frog in the family Hemiphractidae. Stefania evansi is, along with other closely related frogs, known for its unusual reproductive mode where females carry the eggs and juveniles on their back. It is sometimes known under common names Groete Creek carrying frog, Groete Creek treefrog, or Evans' stefania. These names refer to its type locality, Groete Creek in the region Essequibo Islands-West Demerara, Guyana, where the holotype was collected by one Dr. R. Evans.
Phrynomantis microps is an African frog with many interesting adaptations to the savannah. These frogs are also called the Accra snake-necked frog. They are found across Western and Central Africa. One of its distinguishing features is the peptide secretion on its skin, which goes beyond toxicity and seems to inhibit aggressive behavior like biting and stinging from large ants. This allows Phrynomantis microps to live in humid burrows within large ant nests and termite mounds, where they are frequently found. While Phrynomantis microps feeds on similar insects such as the termite Macrotermes bellicosus, they have never been found to feed on the ants they share the nest with. These frogs are medium-sized and have a bright red pelvic region.
Polypedates leucomystax is a species in the shrub frog family Rhacophoridae. It is known under numerous common names, including common tree frog, four-lined tree frog, golden tree frog or striped tree frog. Many past authors have united it with the common Indian tree frog in P. maculatus, but today they are generally considered distinct species. In its native range, it is also called "white-lipped tree frog", but this name is otherwise applied to a species of true tree frogs.
Djoko Tjahjono Iskandar is an Indonesian herpetologist who studies the amphibians of Southeast Asia and Australasia. He is a professor of biosystematics and ecology at Bandung Institute of Technology in West Java, Indonesia.
Nimbaphrynoides is a monotypic genus of true toads from highlands in the Mount Nimba region of the West African countries of Guinea, Liberia, and Côte d'Ivoire. The sole species is Nimbaphrynoides occidentalis. Along with Nectophrynoides, Eleutherodactylus jasperi, and Limnonectes larvaepartus, Nimbaphrynoides is one of the only anurans that combine internal fertilization with ovoviviparity.
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water ; the physical act is known as spawning. The vast majority of aquatic and amphibious animals reproduce through spawning. These include the following groups:
Gosner stage is a generalized system of describing stages of embryonal and larval development in anurans. The Gosner system includes 46 numbered stages, from fertilized embryo to the completion of metamorphosis. It was introduced by Kenneth Gosner in 1960. The system is widely used in herpetology to describe exotrophic tadpoles. Gosner stages are based on certain morphological landmarks that allow comparing development in different species that may greatly differ in age or size.
