The mammalian behavior depends on its physical structure and its lifestyle. Mammals are endothermic, so they need more energy than ectothermic of the same size. The thermoregulation plays a vital role in the way mammal behaves. Sensory organs affect mammalian behavior.
Hair is composed of keratin and is modified epidermis. Mammalian hair is highly variable. It varies in form, shape, density and color location not only within an organism but also throughout the year. Most of this variability relates form and function. All hairs have a nerve plexus at their base. Hair is categorized as vibrissae (whiskers), fur, or guard.
The mammalian lower jaw is hinged directly to the skull, instead of through a separate bone (the quadrate) as in all other vertebrates. The structure of mammal’s teeth can determine the hunting behavior of mammals. Lions, for example, can hunt by using its limbs and sharp teeth to control its prey. Some mammal species that live in territories will defend their areas by pushing away other individuals.
They are usually born alive and relatively well-developed, having grown inside the mother’s body in a special organ called a uterus. The time spent developing in the uterus before birth is called the gestation period and varies in length from species to species (from about 13 days in the Virginia opossum to 210 days in the white-tailed deer).
They have larger and more complex brains than any other group of animals. Mammal species occupy a wide range of Earth's surface. They existed in all continents and all marine ecosystems. There are around 5000 species of living mammals, classified into 125 families and 29 orders. There are three main classes of mammals;
*Placental mammals,
*Pouched Mammals, and
*Monotremes Mammals
Mammalia
