Techniques
Freeze branding
Freeze branding was first used as a technique for individually marking anurans in 1976 by Daugherty. Since then it has largely been neglected by herpetologists, but has proved very effective for permanent individual marking of Xenopus laevis.

Pieces of copper wire, bent into the shape of numbers, are placed into liquid nitrogen until boiling stops. The brand is momentarily placed for 1.5 seconds on the ventral surface of an X. laevis which has been patted dry with tissue.


 
 

Once branded animals are easily identified by number. This individual (089) was branded 2 years previously. This animal is also marked by Panjet on the right thigh.
 
 
 

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Skeletochronology
Ageing in amphibians has previously relied on morphometric studies, measuring especially snout-vent length and weight of individuals. However, such techniques are inappropriate for sexually mature adults whose size is more significantly influenced by growth rate prior to first breeding.

Skeletochronology, the study of ageing individual organisms from the evidence found in bone tissue, has now been widely accepted as a reliable and efficient method of ageing amphibians.

By taking toes (which eventually regrow), age was found to be accurately obtained by counting lines of arrested growth on bones sectioned and stained with haematoxylin.


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Funnel Trapping
Animals are easily caught with minimum disturbance to their environment using funnel traps. Funnel traps are baited with meat or bones (as Xenopus are attracted to carrion) with are held within a mesh bag to prevent ingestion. As Xenopus are aquatic they can be captured throughout the year in the same habitat, unlike other anurans which may only visit water bodies for a short duration.

Trapping is a very versatile way of capturing animals. Traps can be made in many different ways and set mid water using buoys (as shown here), or at the waters edge. Xenopus will drown without air, so if buoys are used, traps must be checked regularly.
Funnel trapping in Tucson USA
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

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Stomach contents
Stomach contents are easily obtained by flushing the stomach with water. This is a common technique used by herpetologists for dietary studies.

Food mostly consists of benthic invertebrates and zooplanton, although other food items do occur, including terrestrial prey items.


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