In some species a narrow probe will probe deeply into females, and consequently increases the uncertainty of the determination. When the probe is fully inserted into the tail, the fore finger is used to mark the spot on the shaft of the probe to determine the depth. We note that a dead freckled python male was used as a model for this photograph, and that probing a live snake typically requires two people. Smaller diameter probes also increase the chance of puncturing the female hemipenial homolog. This apparently happens with some regularity, and whenever sexing snakes, especially pythons, we have found it strongly advisable to probe both sides of the cloaca.
Most people are right-handed and they tend to direct probing to the left side of the cloaca only.
The hemipenes of males tend to be much more uniform in structure and probe to equal depths. Restraining Snakes During Probing Most snakes do not care to allow themselves to be sexed without a struggle. There are a variety of methods that can be successfully used to hold a snake for this procedure, our only comment is that it's the responsibility of the holder to see that the snake being sexed does not bite the prober. Snakes being probed have an uncanny way of sort of winding back and forth in some state of agitation, to end up biting not the person restraining him, but the person who is not paying attention to the foreparts of the snake, and instead is concentrating on the tail of the offended snake. It's disconcerting to all parties.