As we know commonly, a rat snake is one of a quite large non venomous snake found in Indonesia. Especially in west areas of the country. 

This is the visual distinguishing between male and female of an oriental rat snake (Ptyas mucosus). Where the male has a head that is bigger and looks more stronger, while the female is more tapered and pointed.

But the main difference is actually in the lower jaw. The look of these two snakes are almost in the same size. Because both are a mature partner who are ready to mate.

Male (left), female (right)

The male-female difference in this snake tends to be the opposite of most other snakes. The other snake have a proportion of females are bigger than males. Many also think this snake is a Javanese cobra at night. Because at first glance, if you can't see it too clearly, it'll looks like a Javanese cobra.


Pic. Wikipedia