People who love animals are often considered “sensitive” by those who do not. How often do you find someone who adores dogs or cats? Do you know a person with a horse or a dog as a pet? We have all at one time or another visited a shelter or assisted animals pound to help an animal in need. Those who love animals feel deeply about them.
Animals are multicellular organisms, in the entire biological kingdom Animalia, including all fishes, amphibians, protozoa, unicellular organisms and plants. With few exceptions, animals breathe air, consume organic matter, can move, reproduce, and can recognize colors. The body plans of all animals are based on the arrangement of their cells. All animals share a common set of organs, but each member of an animal class has a unique set of features. Humans are mammals, birds are reptiles, and insects are arthropods.
The word “taxa” in the English language refers collectively to the divisions of animals into two broad categories: true taxa and cryptic taxa. A true taxon is any living animal with both the external and internal anatomy. A cryptic taxon is any animal in which the exact nature and characteristics of its organs are not well known. A great many animals fall into both of these taxa.
The majority of animals belong to one of three main categories of animal life. Among these three are land animals and aquatic animals, both with appendages that enter the water. Within these three general classifications there are many subclasses and numerous species. All land animals and all reptiles are decedents of the Earth’s ancestors. Through evolution, new animals have evolved, replacing older ancestors in most cases.
Insects are among the oldest forms of animals and they share this trait with all animals. Insect reproduction is very simple: the female lays her eggs, which are carried by the male as a parasite through the female’s body. The male then fertilizes the eggs and the female take care of the young. A very simple system. Insects differ from other animals in that their reproductive process is not accompanied by a series of complex steps leading to the pupal stage; this being the case with most forms of e.g.
amphibians and reptiles are representatives of more complex animals. They have organs that are present both in their external form (the body) and in their internal form (the tail and bone structure). Many arthropods are covered with scales. Most amphibians, however, use gills, but there are some unicellular forms of animals that use the tissues of their bodies as homes, in contrast to the water-based animals which use the epidermis as a filter for preventing acid reflux.