A poikilothermic (‘cold-blooded’) amphibian vertebrate (order Anura) with a short body, hindlimbs adapted for jumping and swimming and usually with webbed digits, no tail, protruding eyes high on the head, and a glandular skin through which it exchanges respiratory gases and through which many species secrete substances that are unpleasant to taste or toxic. Dry-skinned species, especially those with wart-like protrusions, are usually called toads, but there is no taxonomic difference between frogs and toads. Adults of all but one species (Barbourula kalimantanensis, Bornean flat-headed toad) possess lungs, but breathe by expanding the throat to draw air through the nostrils then raise the floor of the mouth to force air into the lungs (buccal pumping). Most frogs lay eggs (frogspawn or toad spawn) in water, the eggs hatching into larvae called tadpoles (pollywogs). Larvae are typically herbivorous, most adults carnivorous. Frogs occur in moist habitats, but some species have adapted to dry conditions. They vary greatly in size. There are about 4800 species, found worldwide except for Antarctica.