Categorias: Todos - mammals

por Anna Motto 5 anos atrás

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Mammals

Mammals can be categorized into three primary groups: placental mammals, marsupials, and egg-layers. Placental mammals, which include species such as humans, cats, and dogs, give birth to live young that develop to an advanced stage inside the womb, receiving nutrients through a placenta.

Mammals

Mammals

Egg-layers

Brains do not have connective tissue between the two hemispheres. Similar to reptiles because they have a spur in their ankle area.
Endothermic which means they maintain their body temperature inside. Has hair on body. Four chambered heart.
Also known as Monotremes. One opening for urination, defecation, and reproduction.
Oviparous which means they lay eggs. Fetus develops outside of the body.

Examples: Platypus and Echidna

Placental

Mother provide milk to feed the young from their mammary glands.
Young are born at an advanced stage. Almost 4,000 known species of placental mammals.
Give birth to live young that get their nutrients from a placenta inside the mother's womb.
Viviparous means they give birth to live young. The young developed over time outside of the womb.

Examples: Humans, Cats, Dogs, and Horses

Marsupials

The pouch of the marsupials provides a place for the young to finish their development.
Gestation period only lasts a few works before the fetus is born and then placed in the pouch to finish development.
Give birth to live young then the young live inside a pouch until they are old enough to leave.
Most live in Australia or the Americas.

Examples: Kangaroos, Wallabies, Koalas, Possums, Wombats