Multiple choice Which of the following groups of mammals is considered to be toothless? Echidna, armadillos and platypus Whales, marsupials, anteaters and platypus Bat, whales, marsupials and echidna Echidna, whales, bat and platypus Reveal answer Fill a bubble to check yourself A Correct answer Explanation Echidna, armadillos and platypus are considered to be toothless mammals.