Everything You Ever Wanted or Needed to Know About Mammals
Introduction
Mammals are probably the most familiar group of invertebrates there are. Mothers produce milk for their young. They are actually named "mammals" because the mothers produce milk with their mammary glands, which all female mammals have. Mammals have hair covering their entire body, with few exceptions. They cover mostly land, but quite a few have adjusted to water and air. Their way of successful survival over so many years is based on their ability to maintain a stable internal body temperature, no matter what the change in outer temperature conditions may be. Another reason is due to their ability to adapt to new environments and change the way they behave when different circumstances exist.
Anatomy
Most differences in the anatomy of mammals and other vertebrate lies within the unique structure of the skull. They, onlike other animals, have a lower jaw that directly connects to the rest of the skull. The jaw is also made up of only one single bone. This makes the jaw on a mammal capable of cutting food. Another difference is the teeth. All mammals have three types of teeth; canines (for ripping and tearing flesh and other food sources), incisors (which are used solely for the bite), and cheek teeth, or molars and premolars (for grinding food to make it swallowable). Although all mammals have the same types of teeth, the size and shapes come in a wide variety, all depending on the specific diet of the animal. Another major difference between mammals and all other animals, is that they have external ears that are capable of moving (in most cases). This allows them to locate diverse sounds, which then go to the eardrum allowing the sounds to register in their brain. Mammals are the only animals that have skin made up of both an epidermis and dermis. This plays the part of regulating temperature, attracting mates (sebaceous glands), and protection.
Reproduction
In all mammals, fertilization is internal. Some lay eggs, and the rest produce live young. In marsupials, the babies are kept in the mother's pouch because they make no placenta. Most mammals are placental, in which offsping develop in the uterus of the mother. Litter sizes vary from 20 to just a single one.
Socializing
Mammals communicate with one another by scent, body posture, facial gestures, sound and touch. The process starts at birth because offspring must communicate with their mothers. Some mammals only interact when they want to mate, and some to nurture young. Many stay in social groups throughout their entire lives.
Locomotion
Mammals have a number of different ways to move aroud. Quadrupedal, or four-footed gait is the most common way of getting around when it comes to mammals, but some are bipedal, or two-footed gait. Some, such as all forms of bats, are aerial (by flight). Even lemurs have a diefferent way of getting around; they are arboreal (by tree). Aquatic mammals, such as dolphins, are aquatic.
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Marsupials
Egg-Laying Mammals
More to come :)
