Do you remember your first animal drawing? Most people will answer “yes” with an emphatic “no.” That’s because for many people, their first introduction to animals is through a pet or other animal companion. Animals are multicellular, living organisms that constitute the animal kingdom. With few exceptions, animals breathe oxygen, eat organic matter, can move, reproduce sexually, and develop a sort of shell, the blastula, on a shallow layer of cells called the exoskeleton.
One class of animals that most people would not immediately think of when discussing animal research are invertebrates. Invertebrates are animals without a skeleton. Some of the more familiar invertebrates are such things as crabs, lobsters, shrimp, and crayfish. These animals often make up a significant portion of the aquatic aquarium population. invertebrates are especially interesting to scientists because they have complex life cycles and adaptive traits that are shared by several different classifications of animals.
One class of animals that most people would not think of as animal friends are reptiles and amphibians. Snails, slugs, chirping birds, salamanders, frogs, turtles, and constrictors all belong to the reptile family. These animals provide an important role in the ecosystems of both land and water by providing food, protecting the substrate, and regulating the temperature of their bodies. In fact, reptiles are among the most studied animals in the field of animal biology and conservation.
The three major groups of vertebrates are amphibians, which include fish, amphibians, and reptiles, and cephalopods (which include the crab). All amphibians are equipped with sensitive nerves and specialised tissue types called archedectal cells that allow them to remain submerged in water. The unique ability to dive and retain an oxygenated body below the surface are what gives these animals their long lives. Many cephalopods (such as shrimp and lobsters) possess gills which have evolved into airbags, allowing them to stay underwater for extended periods of time. One of the key takeaways here is that any animal with an effective breathing mechanism can adapt and survive in a wide range of environments.
An important group of animals with specialised cell types and structures is the epithelial tissues, or the skin and muscle layers. Animals have very specific requirements for their epithelial tissues depending on their environment, including temperature, diet, water availability, stress, etc. All aspects of these specialized tissues are critical in ensuring the longevity and health of the animal. Some of the key points to consider are the differences in the maintenance requirements of animals, the impact of growth and metabolism on epithelial tissues, and the importance of repairing damage.
A further interesting group of animals in the animal kingdom are the sub-mammals or those animals under the hair or fur, including mammals and birds. As a classification, sub-mammals do not have a skeleton, but retain their soft bodys as a cushion. They have adapted wonderfully well to their environment by having a series of organs which perform specific roles in the body. Although the various aspects of these animals are similar to us, there are key differences in the physiology and lifestyle of a cat or dog compared to a mouse or rat. These examples demonstrate the continuing need for more research and analysis of animal physiology and anatomy.