Wednesday, 15 May 2013

Polliwogs ...

Polliwogs and Porwigles

The common frog (Rana temporaria) is found throughout Britain and Ireland, in almost any habitat where suitable breeding ponds are located. The adult frogs, which typically emerge from their overwintering sites during early spring, head straight to a pond or other suitable location in order to breed; frogs reach sexual maturity at around 2-3 years old.

Their clumps of spawn (eggs) are laid in suitable locations anytime from January (in south-west England) onwards, and typically consists of 300-400 gelatinous eggs containing tiny black embryos. Depending on local weather conditions, the tiny, gilled tadpoles hatch out two to four weeks later. As they develop the tadpoles become faintly speckled with gold/brown (as can be seen in the picture below), which clearly distinguishes them from common toad tadpoles, which are black. They feed on microscopic algae and water fleas. After approximately sixteen weeks the tadpoles start to develop back legs, followed by front legs. When they have fully absorbed their tails, through a process known as apoptosis, they leave the water as tiny froglets, usually in early summer but sometimes as late as September.

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