Organisms that feed on the excreta of other organisms are called

Coprophagia or coprophagy is the consumption of faeces. Coprophagy refers to all kinds of faeces eating including eating faeces of other species (heterospecific), of other individuals (allocoprophagy), or its own (autocoprophagy), those once deposited or taken directly from the anus.
So, the correct answer is 'Coprophagus'