Amphibian
Parental care

The care of offspring among amphibians has been little studied but, in general, the larger the number of eggs in a batch, the less likely it is that any degree of parental care takes place. Nevertheless, it is estimated that in up to 20% of amphibian species, one or both adults play some role in the care of the young. Those species that breed in smaller water bodies or other specialised habitats tend to have complex patterns of behaviour in the care of their young.

Many woodland salamanders lay clutches of eggs under dead logs or stones on land. The black mountain salamander (Desmognathus welteri) does this, the mother brooding the eggs and guarding them from predation as the embryos feed on the yolks of their eggs. When fully developed, they break their way out of the egg capsules and disperse as juvenile salamanders. The male hellbender, a primitive salamander, excavates an underwater nest and encourages females to lay there. The male then guards the site for the two or three months before the eggs hatch, using body undulations to fan the eggs and increase their supply of oxygen.

The male Colostethus subpunctatus, a tiny frog, protects the egg cluster which is hidden under a stone or log. When the eggs hatch, the male transports the tadpoles on his back, stuck there by a mucous secretion, to a temporary pool where he dips himself into the water and the tadpoles drop off. The male midwife toad (Alytes obstetricans) winds egg strings round his thighs and carries the eggs around for up to eight weeks. He keeps them moist and when they are ready to hatch, he visits a pond or ditch and releases the tadpoles. The female gastric-brooding frog (Rheobatrachus spp.) reared larvae in her stomach after swallowing either the eggs or hatchlings; however, this stage was never observed before the species became extinct. The tadpoles secrete a hormone that inhibits digestion in the mother whilst they develop by consuming their very large yolk supply. The pouched frog (Assa darlingtoni) lays eggs on the ground. When they hatch, the male carries the tadpoles around in brood pouches on his hind legs. The aquatic Surinam toad (Pipa pipa) raises its young in pores on its back where they remain until metamorphosis. The granular poison frog (Oophaga granulifera) is typical of a number of tree frogs in the poison dart frog family Dendrobatidae. Its eggs are laid on the forest floor and when they hatch, the tadpoles are carried one by one on the back of an adult to a suitable water-filled crevice such as the axil of a leaf or the rosette of a bromeliad. The female visits the nursery sites regularly and deposits unfertilised eggs in the water and these are consumed by the tadpoles.
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