frog

Frog is a common name for amphibians in the order Anura, comprising about 6,000 described species. Frogs typically have short bodies, smooth or warty skin, and powerful hind legs for jumping, with no tails as adults. They occupy a wide range of habitats, from deserts to rainforests, but most require moist skin and standing water for breeding. Eggs are laid in water and hatch into tadpoles.

Anatomy and physiology: Adults have webbed hind feet and strong leg muscles for leaping. They possess a tympanic membrane behind the eye and a protective nictitating membrane. The skin is permeable, aiding water balance and gas exchange. Breathing occurs through lungs and skin; tadpoles use gills and a tail fin. Many species have vocal sacs that amplify mating calls.

Life cycle and reproduction: Most frogs breed in water. Males call to attract females, and amplexus follows, with the male clasping the female. Eggs are laid in gelatinous masses and fertilized externally. Eggs hatch into aquatic tadpoles with gills, a mouth, and a tail; after weeks to months they metamorphose into adults. Some species have direct development, bypassing a free-living tadpole stage.

Ecology and behavior: Frogs are primarily insectivores; larger species may eat small vertebrates. Tadpoles often feed on algae and plant matter. Frogs occupy many ecological roles as both predators and prey. Many species bear skin toxins, and coloration may provide camouflage or warn predators.

Conservation and distribution: Frogs occur on every continent except Antarctica, in many habitats. They face threats from habitat loss, pollution, climate change, disease such as chytridiomycosis caused by Batrachochytrium dendrobatidis, invasive species, and overcollection. Conservation actions include habitat protection, monitoring, and captive breeding, with many species assessed by the IUCN Red List.