PHI208 Ashford University Denying Moral Consideration to Animals Discussion

Singer argues that there is no moral justification for denying moral consideration to animals.

Can you think of a reason why our moral consideration should include all humans regardless of their level of cognitive ability, yet denied to non-human animals simply because they have lower levels of cognitive abilities (though still higher in some cases than those of human infants and some mentally disabled humans)? To further clarify….it does seem possible that an adult dolphin may have a higher cognitive ability than an infant or a mentally handicapped person.
What response might Singer have to your way of drawing the line between the types of beings that should get moral consideration and those that should not?