They are not found on Monotremes ( the platypus and the echidnas or spiny anteaters ) and a few eutherian orders , namely the bats ( Chiroptera ) , whales , dolphins and porpoises ( Cetacea ) and pangolins ( Pholidota ) . They are obligate ectoparasites of every avian and mammalian order except for Monotremes ( the platypus and echidnas ) , bats , whales , dolphins , porpoises and pangolins .