Female Anthracocentrus arabicus are approximately 6 times less abundant than males (Rejzek et al 2005) and so males must compete for access to females. This may explain why the males have evolved large, ferocious-looking mandibles, which they can use in fights with each other.
This species is remarkably variable in size, with females being on average larger than males. Males range from 28–86mm in length, whilst females range from 50–95mm.
Large male individuals possess exaggerated mandibles, whilst small males look superficially similar to females.
The fierce mandibles are also used in defence. For example:
The bite itself is very strong and can easily cut through human skin and cause considerable pain.