July 6, 2022

Frog (or frog, granyota and, archaically and dialectally frog) is the name of general use to designate several amphibians of the order of the anurans. Specifically, it refers to all members of this order who do not have rough skin on their backs, as these are often called toads. These amphibians usually live in freshwater places such as ponds and rivers. More than 90% of frog species belong to the Ranidae family. Some species, such as the green frog (Pelophylax perezi), the common frog (Pelophylax ridibundus) and the red frog (Rana temporaria), are common in Catalonia and the Balearic Islands. The red frog is actually pinkish brown, the jumping frog (Rana dalmantina), which inhabits some parts of Europe, is red.


Frogs have a rather peculiar morphology because the head and thorax form an undifferentiated unit. With the head as wide as it is long, the eyes protrude far, with the pupil upright, the tongue protractile, and the upper jaw provided with teeth. In Europe they are usually between 9 cm and 15 cm long, but the largest in the world, which inhabits Africa, is 33 cm long and weighs 2 kg (goliath frog or Conraua goliath). The trunk is oval, with the short forelegs and the long hind limbs, with the fingers joined by a membrane. The skin is smooth and of a variable uniform color (greenish, earthy, blackish, brown) or with spots. On the other hand the smallest vertebrate of the world is the species of frog of New Guinea Paedophryne amauensis, that goes discover in 2009. The male has two vocal sacs that produce the characteristic hoarseness. Its means of communication is through vocal sounds produced by the larynx. They usually have serious, or hoarse cries. The onomatopoeia of this sound in Catalan is: «roc-roc», and it is said that «rauquen». The frog inhabits still waters, such as ponds, ponds or wells, and also in torrents and streams with abundant vegetation. Reproduction takes place during the spring, when each female lays five thousand to ten thousand eggs surrounded by a gelatinous mass, which for four months metamorphose and become tadpoles and adults. They follow the common reproduction of all amphibians, by means of eggs without shell which need a constant humidity. In adulthood they have no tail, have dual, pulmonary and cutaneous respiration, and have four legs unlike the earlier stages of the species, such as the tadpole. In winter they hang in the mud and remain lethargic. The frog has a genome made up of 1.7 billion chemical bases deployed on 10 chromosomes and 1,700 genes.

Particular frogs

There is a hairy frog (Trichobatrachus robustus), which has long hairs that penetrate the capillaries and are believed to have a respiratory role. In Chile there is the so-called marsupial frog (Rhinoderma darwini). This frog, only three centimeters long, manages to make jumps of more than half a meter. In addition, it is also a climber. In China, Indochina, the Philippines and the Sunda Islands there is the so-called flying frog (Racophorus sp), which is about eight centimeters long and is characterized mainly because it has a skin fold that goes from the back angle. from the eye to the back, which may resemble a mantle or cloak or wings. In Thailand, in the valley of the Mekong River, there is a big-eyed frog (Limnonectes megastomias), with long tusks, which, in addition to insects, feeds on birds. In Indonesia there is a frog that has a pointed and retractable nose, which heads upwards at the call of the male and deflates and points downwards when it is less active. Some American frogs contain poison, and in Costa Rica and Ecuador there are species that do not have it, but copy (mimic) the appearance of poisons to protect themselves from potential predators.


The structures of gene segments