An animal (plural: animalia) is defined as any of the chordates of the Kingdom Animalia, to which all other forms belong, to have no muscular cords, excluding sharks and cephalopods. Among all the chordates, dogs are the only ones that are classified into two main categories: carnivores and herbivores. Herbivores eat plants or flowers, but not animals. Carnivores eat animals and plant material, but also some plants, although these are usually animal foods. In both cases, omnivores and carnivores (or both) exist in groups.
The word “animal” is thought to have come from the Greek word “anigra”, which means “of the animal kingdom”. Over the years, various theories have been advanced to explain the origin of the word, including those related to the early evolution of man, the idea that certain animal species were the result of accidental crossing with members of other animal families, and that dinosaurs became extinct millions of year ago. It has also been suggested that the origin of animal research may be to support field studies involving mammals, birds and invertebrates (such as shrimp, squid and fish), used for biological, ecological and medical purposes. Recent advances in the scientific community have revived interest in animal research, with a renewed interest in the behavior and intelligence of animals and in their relationships with us.
In this paper we shall consider recent advances in this area. Firstly, we shall consider whether there are any special forms of animal behavior and in particular the behavior of animals in the laboratory. A major breakthrough in this area was achieved via the work of ethologist Martin Davis in the early 1990s. He showed that animals can reproduce asexually, by mating together and then dividing asexually without any offspring being born, referred to as infertile reproduction.
The work of developmental biologists has also made significant advances recently, especially in regard to amphibians and reptiles. We know that reptiles such as frogs are capable of reproduction asexually, but not yet all amphibians have been able to do so. amphibians and reptiles are closely related to birds and mammals, but amphibians have lost most of their specialized features that made them unique among mammals. Some have regained limbs lost in evolution, but most have lost hooves, claws and even tails. reptiles are very closely related to snakes and lizards, but they have lost most of their wide range of appendages, including the tail.
Studies of animals at the molecular level are also helping to clarify the relationship between animals. Recent work has shown that cells within an animal kingdom such as vertebrates are arranged in complex patterns to enable them to move and live. The work of cellular biochemists is showing that cells are composed of protein complexes rather than single protein molecules. They are made of DNA wrapped around a membrane bound coiled regions. Animals do not generate DNA but rather regulate the generation of DNA through expression of genes from specialized cells called promoters. These cells also send signals to other cells through the cells’ membrane, directing them to grow and divide into specialized units.
Finally, animals manufacture their own proteins as part of their normal metabolism process. Protein production requires energy and is coordinated by a series of sophisticated mechanisms within the animal body. Studies of animals are revealing that animals are capable of designing their own cellular proteins, a feat not duplicated in e.g. humans. Evidence is also emerging that animals can manipulate the expression of genetic material-something not possible in e.g. humans.