Speciesism involves assigning different values or rights, or special consideration, to individuals solely on the basis of their species membership. The term was coined in 1973 by British psychologist Richard D. Ryder to denote prejudice against non-humans based on morally irrelevant physical differences.
The term is mostly used by animal rights advocates, who argue that species membership has no moral significance, and that it is both irrational and morally wrong to regard sentient beings as objects or property. Philosopher Tom Regan argues that all animals have inherent rights and that we cannot assign them a lesser value because of a perceived lack of rationality, while assigning a higher value to infants and the mentally impaired solely on the grounds of membership of a certain species. Peter Singer's philosophical arguments against speciesism are based on the principle of equal consideration of interests.
One argument used to show that speciesism is an arbitrary discrimination is called the argument from marginal cases. This says that if marginal-case human beings – such as infants, the senile, the comatose, and the cognitively disabled – have a certain moral status, then non-human animals must have it too, since there is no morally relevant ability that the marginal-case humans have that non-human animals lack. "Moral status" may include a right not to be killed or made to suffer, or a general moral requirement to be treated in a certain way.
Please feel free to read more at the link provided above. Speciesism has caused as much harm as racism in this world, and neither are on their way to ceasing to exist.