Singer rests his arguments on the rejection of ‘speciesism’: a type of discrimination that Singer likens to sexism or racism, but on grounds of species. For Singer, we might differ in how we treat an animal on the grounds of cognitive capacity, but never just because it is a different species. For example, he argues, if you would be willing to kill a pig and harvest its organs to benefit people (if they were human-compatible), you should be willing to do the same to a human infant born without parts of its brain and skull, which has less mental capacity than the pig.
Is there a word like this but at a higher level than species? An example of the concept I would like to describe is our tendency to consider birds of less intelligence than mammals, and therefore treat them worse. This may explain the particularly poor conditions of intensive poultry production despite for example recent work showing that chickens can recognise themselves in the mirror. As mammals and birds are different classes "classism" may have been chosen, but that is already "taken". Another example may be the protection given to vertebrates by UK animal welfare legislation, but denied to invertebrates including octopuses and lobsters that are recognised as sentient.