The Animal Kingdom is very diverse, containing many unique members. Because there are so many animals, scientists have divided them into groups. These groups were decided on according to characteristics that it’s members shared, whether they were physical or behavioral.
This is what we call the system of CLASSIFICATION.
The largest of these groups, not in size but in number, are the INSECTS.
Insects are INVERTEBRATES, or animals with out backbones. They are also
in the phylum, ARTHROPODA, which means, “jointed legs”. They share this
phylum with spiders, the crustaceans (lobster, crabs, etc.), scorpions and other creepy-crawly things such as centipedes and millipedes. All though they share the same phylum as other arthropods, they possess two major differences. Insects have SIX LEGS and THREE BODY
PARTS, which consists of the head, thorax and abdomen. The 3 pairs of legs are attached at the thorax. This is very different than say, spiders, which have eight legs and two body parts. Insects also have an EXOSKELETON, also known as the “shell” for protection and camouflage. Because they do not have an internal skeleton, it is on the outside, hence the term “exo”skeleton. Insects may also go through one of two METAMORPHOSES or “change of form.” Insects
such as butterflies and moths go through COMPLETE METAMORPHOSIS (egg, larva, pupa
and adult) and other insects such as grasshoppers and crickets go through INCOMPLETE
METAMORPHOSIS (egg, nymph and adult.) Zoologists that study insects are called ENTOMOLOGISTS.
REPTILES and AMPHIBIANS are another group of animals belonging to the branch of
zoology called herpetology. Although both groups of animals are very different, they were grouped together because it was once thought that they were closely related. One characteristic that both groups share is that they are COLD-BLOODED or ectothermic. This does not mean
that they have “cold blood”, rather, their environment, or the outside temperature
regulates their body temperature. In addition, reptiles have the presence of SCALES
on their skin and amphibians do not. Scales not only protect a reptile’s skin from
abrasions but they also help to prevent desiccation (drying out.) Amphibians tend to
have a SLIPPERY/SLIMY SKIN for protection against disease and predators and to
prevent drying out in short periods of drought, or lack of water. The life cycles of amphibians and reptiles very greatly as well. An amphibian’s life cycle is a very unique METAMORPHOSIS, or “change of form.” They begin as an EGG, develop into the
LARVAL OR TADPOLE STAGE, than once they lose their tail, they become and ADULT.
Reptiles do not go through a metamorphosis. When they hatch from their egg, they look exactly like an adult, just smaller. Zoologists that study reptiles and amphibians are called HERPETOLOGISTS.
BIRDS are a very unique group of animals because they possess
FEATHERS. Feathers serve several functions. Besides providing them
with flight, they also give birds their shape and colors and they also keep them warm. Birds are WARM-BLOODED animals, meaning that their body
temperature is controlled internally. Bird’s feet and beaks are specially adapted to their habitat
and diet. For example, a hawk’s beak is designed to tear meat, whereas a cardinal’s beak is designed to crack seeds. A very unique characteristic of birds is that they also have HOLLOW
BONES, similar to a straw. This is very important as it makes birds very lightweight for flight. Zoologists that study birds are called ORNITHOLOGISTS.
MAMMALS are one of most recognizable groups of animals. Two unique characteristics of mammals are that they have FUR or HAIR and MAMMARY GLANDS. Fur provides
mammals with heat and camouflage as well as protection from external parasites such as fleas
and ticks. Mammary glands provide milk production for females as a food source for
their young. Mammals are also WARM-BLOODED, just as birds are. Another
characteristic unique to mammals is that they will have two sets of teeth their entire
life. Mammals have “differentiated teeth” meaning that they can have four kinds of teeth that serve different functions (incisors, canines, premolars and molars.) The set of teeth that can be observed on a mammal skull will tell you the type of diet that it had; whether it was a HERBIVORE, CARNIVORE or an OMNIVORE. Mammals are categorized into many
groups according to similar characteristics that their members share, i.e. dog family, cat family, rodent family, etc. Zoologists that study mammals are called MAMMALOGISTS.
FISH are another unique group of animals because they live their entire lives in water and they
don’t have lungs. They breathe through GILLS. A fish’s skin consists of SLIMY SCALES,
which aids in disease prevention. Today we have two types of fish--the bony
fish (sunfish, trout, etc.) and the cartilaginous fish (sharks.) Cartilaginous fish have a skeleton made up of cartilage, the same material that our nose and ear tips are made up of. Just like amphibians and reptiles, fish are also COLD-BLOODED. Fish
are divided up into families according to shared characteristics. Some of these include catfish, sunfish (perch), trout, bass, gar, and many more. A zoologist that studies fish is called an ICHTHYOLOGIST.
Compiled by Jessica Lawrenz