Lars Osterdahl

When tadpoles are raised under controlled conditions, their development either for a clutch or for individuals should be recorded.

A simple method of denoting their development stage is needed, and that developed by Gosner is finely divided with 47 'stages' from egg to metamorphosis. His system is generalised for all frogs and is not particularly suited to Dendrobatids. Whilst this is a very accurate method, it is only of use to those with scientific equipment to closely examine the developing tadpole.

The coding system described here was developed before I knew of Gosner's system. It was important to note the stages of many individual tadpoles in a short time and without the need to look at them with a magnifying glass. It seemed practical to divide the development into 10 stages that were easy to identify with the tadpoles still in their jars and with debris and algal growth on the glass. It is important to note that I do not suggest that my 'system' should replace that of Gosner in scientific practice, but only serve as a simple alternative in rearing work.

In my diary I noted the development stages using words such as 'newly hatched', 'small hind-legs', 'elbows' etc. The codes 0-9 were used when the data was put onto a spreadsheet.

Gosner, K.L. 1960. A Simplified Table for Staging Anuran Embryos and Larvae. Herpetologica, 16:183-190