Mammal Characteristics General Characteristics  Warm – blooded, air‐breathing, four‐legged vertebrates.  Hair and sweat glands help maintain temperature  The pattern and arrangement of teeth dictate what type of food it eats.  Diaphragm separates thoracic from abdominal cavity.  Has a four‐chambered heart and a well developed nervous system.  Usually have 5 toes (as a result of an adaptation to running) o Some have adapted their limbs to other activities: burrowing (mole), swimming (dolphin) etc.  Hind limbs are primarily involved in movement, allowing front ones to do more specialized tasks. Keeping Warm  Most terrestrial animals have a dense coat to keep them warm.  Made of outer guard hairs and short underhairs, which provide excellent insulation.  In hot climates, hair can prevent too much heat absorption.  Some mammals have specialized hairs; porcupines outer hair = spiny quills for defense.  Hair is made of the protein keratin, which is also found in antlers, fingernails and claws. Feeding  Most visible characteristic is types and arrangement of teeth in the mouth.  Four types: incisors, canines, premolars, molars.  Teeth in both upper and lower jaw line up, which helps in chewing.  Each tooth is specialized: o Incisors: biting and tearing. o Canines: holding and piercing its prey. o Premolars & molars: chopping and grinding food.  Animals are identified by a specific dental formula: represented by the specific number of each tooth from front to back on one side  Humans: 2123/2123 = 2 incisors, 1 canine, 2 premolars, 3 molars  For food eating animals, their digestive systems is specialized in breaking down cellulose o The stomach system consists of 4 chambers, which includes enzyme, bacteria, mechanical and chemical digestive strategies. Running  Endoskeletons have 3 advantages: o Can grow without moulting. o B/c they don’t moult, they are not vulnerable during growth. o Do not divert metabolic energy to produce a new skeleton.  Due to joints and well‐developed muscles and bones, the skeleton is flexible.  The structure of the limbs allow for easy locomotion  Limbs of various mammals have adapted to a specific activity: o A cat’s claws allow for holding down prey o A human’s foot allows for bipedal motion. Mr. Piwowarczyk