The male echidna has five X chromosomes, but only four Y chromosomes, whereas the male platypus has five X and five Y). During production of sperm and eggs (meiosis), these sex chromosomes pair in ...

What is the echidna? Echidnas are part of a group of animals called monotremes, which is the only group of mammals that lay eggs instead of giving birth to live young. Echidnas are one of only ...