Class Mammalia (Phylum Chordata)
Examples and Traits
Class Mammalia is home to Humans, along with other mammals such as cats, dogs, horses, giraffes, marsupials and many others. There is about 4000 species in Class Mammalia. They are amniotes, and have hair made of keratin. They have Mammary glands which produce milk for their young. They are endothermic. They have a diaphragm which helps with respiration. They have three middle ear bones. The diet of the species impacts the digestive tract (the length of the intestine and cecum). They have a four chambered heart. Their brains are highly developed with a cerebral cortex, which runs deeper thinking. There are three reproductive groups among the mammals; monotremes, marsupials and placental mammals. monotremes produce eggs; platypus and echidna are the only egg laying mammals. Marsupials give birth to undeveloped young, and complete development nursing in the marsupium, which is the pouch. Placental mammals have a uterus where the baby grows in. They have a placenta, which is a temporary organ grown in the uterus by both the mother and the baby, that is used to transfer nutrients from the mother to the developing baby. The placenta is usually eaten by the mother after giving birth.