Research and Specialties Many veterinarians choose to research a specific veterinary medicine topic. These professionals often earn advanced degrees and certification in veterinary science or related fields such as biochemistry. Usually affiliated with veterinary colleges or universities, research veterinarians provide expertise for the specialized diagnostic testing or treatment that some animals require. Pharmaceutical research concerning the control of parasitic heartworms and the parvovirus were two of the most outstanding twentieth century developments in veterinary medicine. The parvovirus, an acute, contagious intestinal disease, was first identified in 1978 in the United States and is the most common infectious canine disorder. Many veterinary experiments explore the role of genetics in health and also examine alternative methods for reproduction, such as artificial insemination and embryo transplantation. Veterinarians also devise methods to use technology such as ultrasound to diagnose animals' ailments. Most veterinary medicine specialties address physiological aspects such as dentistry, dermatology, radiology, cardiology, orthopedics, nutrition, toxicology, anesthesiology, pharmacology, and ophthalmology. Other specialties concern animals' intellectual and emotional capabilities; veterinarians specializing in behavior seek new ways to measure how animals react to stimuli and how to utilize this information to train animals. Some veterinarians also address legal and ethical issues related to veterinary medicine. Others seek alternative veterinary medical techniques through holistic healing, massage, and acupuncture. Because advances in veterinary medicine have resulted in animals aging beyond previously expected life spans, geriatric practices have gained demand. Veterinarians are exploring new ways to treat conditions associated with old age, such as arthritis, cancers, organ failures, and reduced senses. Some veterinarians participate in ventures such as Operation Arctic Care to vaccinate and examine animals in remote regions who would otherwise receive no veterinary attention.
Mutualism The most diverse type of commensalism is mutualism. In some works, particularly those dealing with animal behavior, mutualism is used as a synonym of symbiosis; hence, the reader must use caution in order to determine an author's usage of these terms. As used here, mutualism is a special case of commensalism, a category of symbiosis. The relationship between mutuals may be obligatory on the part of one or both species, but it is always reciprocally beneficial, as the following examples illustrate. Some species of hermit crabs place sea anemones on their shells or claws (sea anemones are carnivores which possess stinging cells in their tentacles). Hermit crabs without anemones on their shells or claws may be more vulnerable to predators than those with an anemone partner. Hermit crabs, which shred their food in processing it, lose some of the scraps to the water, which the anemones intercept, and eat. Thus, the crab provides food to the anemone, which in turn protects its provider. Such relationships, which are species-specific, are probably the result of a long period of coevolution. Adifferent type of mutualism, but one having the same outcome as the crab-anemone example, is found in associations between certain clown fishes and sea anemones. Clown fishes appear to be fearless and vigorously attack intruders of any size (including scuba divers) that venture too close to "their" anemone. When threatened or attacked by predators, these small fishes dive into an anemone's stinging tentacles, where they find relative safety. Anemones apparently share in food captured by clown fishes, which have been observed to drop food on their host anemone's tentacles. Cleaning symbiosis is another unique type of mutualism found in the marine environment. In this type of association, marine fishes and shrimp of several species "advertise" their presence by bright and distinctive color patterns or by conspicuous movements. Locations where this behavior occurs are called "cleaning stations." Instead of being consumed by predatory fishes, these carnivores approach the cleaner fish or shrimp, stop swimming, and sometimes assume unusual postures. Barracudas, groupers, and other predators often open their mouths and gill covers to permit the cleaners easy entrance and access to the teeth and gills. Cleaners feed on epizoites, ectoparasites, and necrotic tissue that they find on host fishes, to the benefit of both species. Some studies have shown that removal of cleaning symbiotes froma coral reef results in a significant decrease in the health of resident fishes.
