Mammals come in a wide range of shapes and sizes, from the tiny mouse to the huge whale, but they all have the same basic body plan.
Vertebrates
Vertebrates are animals with a spine, and mammals definitely fall into this category. Bone is the hard tissue that makes up the vertebrate skeleton and forms a frame to protect the animal’s organs. It also gives the animal its body shape and allows for movement. Cartilage, the soft but tough tissue, is found in ears, noses and on the ends of bones in mobile joints.
Nerves
The spinal cord is a bundle of nerves that begin at the brain, travel down the spine and continues through to the end of the tail. Nerves send signals to muscles, which control reflex movements and control walking and other movement.
Muscles
When the muscles receive electrical impulses from the nerves, they respond by contracting or relaxing resulting in the required action. Muscles are attached to bones by tendons. The joints in between bones form a pivot and pairs of muscles work together to create the desired movement. While one is relaxed, the other contracts.
For example, to do a bicep curl (to raise the forearm at the elbow), the bicep (front of upper arm) muscle must contract, while the tricep (back of upper arm), muscle must relax. This is how muscles work together. If the bicep and tricep muscles were to contract at the same time, you would not get the desired movement of the bicep curl.
Organs
Not only are the muscles attached to the skeleton, but they also surround organ and organ systems. For example the stomach and the intestines are surrounded by muscles and it is these muscles contracting and relaxing that push food and waste products through the body in rhythmic waves.
The heart is a muscular organ that pumps blood through the body by contacting and relaxing. The heart along with other vital organs (eg: lungs, liver), are contained within the thorax, the section between the forelimbs and protected by the ribcage, in mammals.
Vertebrates have a single liver whose function is to make chemicals that the body needs and for storage. Most vertebrates have two kidneys and their function is mostly to filter blood of any toxins and impurities and to remove excess water, which is then excreted as urine.
Differences in Mammalian Anatomy and Body Functions
Despite the huge difference in size and shape between mammals, basic body functions are pretty much the same with some exceptions. Some differences include brain size, differences in digestive systems and skeletal differences.
For example the gorilla has a large brain for its body size, which allows gorillas to live in complex social groups. While the cat is a carnivore, the bear eats both hunted prey and fruit so the bear’s digestive system needs to digest both plant and animal food.
Compare the digestive tracts of a small carnivore such as the coyote to a similar sized herbivore like the koala that only eats leaves. The koala has much longer intestines, particularly the cecum and colon, which allows it to digest fibrous eucalyptus leaves. The elephant has a unique skeleton that is able to support the weight of its heavy body.
Because mammals live in a variety of habitats, from deserts to temperate forests their bodies are adapted to survive the different conditions and climate, and likewise because mammal diets vary, their internal organs vary depending on what they eat.
Roberta Goli - Roberta has a Bachelor of Science Degree (Zoology), has worked with animals for over 10 years and enjoys writing short stories and flash ...
