Christina Bucalo

4-6-98

Animal Diversity Research

Animal Diversity

Although animals may live in the ecosystem, constantly intertwined with one another, they are classified and recognized with extreme differences. The tick and the dog are two common animals known to humans that coexist in the same environment. Ticks are parasitic and feed on the body fluid of the canine. The American Dog Tick and the domestic dog, however, have several differences when viewed from a classification standpoint. Both of these organisms are included in the Kingdom Animalia which represents organisms that are multicellular heterotrophic eukaryotes, that store their carbohydrates as glycogen, and have intercelleular junctions.

The American Dog tick is the largest, most common and widespread of all ticks. The tick does not have a backbone which places it in the Phylum Arthropoda. It is placed in this phylum not only due to the lack of a backbone, but also the fact that it has a segmented body, consisting of two to three regions, jointed paired appendages, and a hard exoskeleton. The American Dog Tick is also placed in the Subphylum Chelicerata because of the number and character of the appendages. There are usually six, the first pair being the chelicerae used for feeding. The second pair are used for feeling and are called pedipalps. Ticks are in the Class Arachnida with spiders, mites, scorpions, and other organisms. The class is named for the four pair of appendages, and the characteristic first pair of appendages, the chelicerea, for cutting into the flesh of their prey. Ticks are classified in the Subclass Acari due to characteristic prelarval, larval, and nymphal stages. The Order which contains the American Dog Tick is Mesostigmata. Mesostigmata contains animals that have an unsegmented abdomen that broadly joins the cephlathorax. The body of these animals is also oval in shape. The Family Ixodidae houses the tick due to its thickened shield on the top of the front region of the body. The genus and species name for the tick is Dermacentor variabilis, which is named after the area of the body the tick feeds from, the dermis. Ticks evolved around four-hundred million years ago during the early Devonian Period. Ticks are extremely difficult to classify and are usually recognized for what they are not.

The domesticated dog, which is quite more complex animal than the tick. The dog, however, differs from the tick in that it is placed in the Phylum Chordata, which represents all animals with a backbone. The dog is then placed in the Class Mammmalia due to the presence of hair made of keratin, a diaphragm, mammary glands, large brains, they also perform internal fertilization, and are endothermic. Dogs are carnivorous with sharp pointed teeth for tearing and piercing which places them in the Order Carnivora. Dogs are placed in the Family Canidae due to the four toes on the hind legs, five toes on the front legs, forty-two teeth, four of which are pointed, and three types of hair. Animals in this family also have a scent gland at the base of the tail and rabies occurs in all animals in the family sporadically. The skeletons of dogs show they all have a long muzzle including a well developed jaw. The teeth all have the same dental formula, which includes canassial teeth and crushing molars. Domesticated dogs also have a well developed personality that is opportunistic, adaptable, and social. All animals in the canis genera have approximately the same longevity and gestation periods. These animals are usually thirty-two to fifty inches in size, however, the domestic dog has a much broader range. Dogs are believed to have originated in North America between fifty-four and thirty-eight million years ago during the Eocene Epoch. The domestic dog, scientifically known as Canis familiaris is thought to have developed from all the other canis genera.

Both the American Dog Tick and the domestic dog are extremely different animals according to their classification, however they do reside in the same ecosystem. The complex environment of the world allows for the success of each of these animals, despite their diversity and varying necessities.