For my Lab Animal research project I will be discussing the Spiny Dogfish (Squalus Acanthias) and its contribution to our society through biomedical research. This dogfish has large eyes, a pointed snout with spines in front of its two dorsal fins (Bester, 2018). In front of each dorsal fin they have spiky, ungrooved, venomous spines, being white in their ventral side with pale gray or white irregular spots, and gray in their dorsal side. They range in size from 3-4 feet and weigh around 3 – 9 kg.
In its natural habitat a Spiny dogfish is found epibethically, this organism lives on or just above the bottom sediments in a body of water, Spiny dogfish prefer seawater and do not enter freshwater habitats, only being able to survive in it for a few hours (Bester, 2018). They venture into shallower bays so adding that into their housing would be beneficial considering they can be found in oceans depths between 32 and 660 feet. Temperature wise, they are usually found in cold and warm areas of the oceans at the temperature between 0-15 degrees celsius. Now focusing on their diet, they mainly feed on fish prey like pelagic fishes such as mackerel, herring, and sand lance. It is believed that they rarely feed during the winter months because they stay in deeper waters. Once it is early spring they appear very thin in appearance in the coastal waters. Spiny dogfish are long distance travelers.
Spiny dogfish form large schools of hundreds to thousands of either the same size or shape. They are highly social species, when migrating to find food, they often scatter and destroy other schools of fish, they can even travel long distances. Regarding enrichment, because they are a social species having them in schools would allow them with their swimming efficiency, and stimulate natural behaviors. Providing unpredictable changes in their environment will mimic behaviors that they show in the wild. That being said items should be added, removed, or changed for their psychological needs. Another source of enrichment can consist of lighting, decor, and feeding. Training should help to be able to get them from one area to another and make it a learned behavior. The name “dogfish ” comes from the fact that they feed and pack and together sweep an area of fishes. There have been complaints from fishermen that the spiny dogfish rip the net to get the fish that were captured. Spiny dogfish have the longest known gestation length for sharks being estimated from 22-24 months. Mating occurs in offshore waters. So in a laboratory facility they would have to mimic that environment if breeding them. They usually mate in the winter time and their young are born in the warmer waters so that is a special accommodation, changing the water temperatures. These sharks are ovoviparous meaning that their eggs are laid and developed inside the females’ body and they are hatched inside as well. Their young are approximately 20 to 30 cm in length and the average litter is 2-11 pups depending on how large the females are.. Sexual maturity in males is reached at a total length of about 64 cm and 10 years of age. Females reach sexual maturity at a later age, around 16 years, at which time they are about 82 cm in total length. (Street, 2002) They do have a long life span which is 25-30 years.
Sharks have many reasons for why it is used for biomedical research. There are similarities between humans and sharks. For one their vertebrates share components like the same immune system. The Spiny dogfish is relevant for the human diseases that affect intraocular research. Another thing that makes the, an ideal model is the rectal gland. They have contributed to the economy, they are used for human consumption, animal feed, for cosmetics and medicine, soup and even shark cartilage for osteoarthritis therapies The Spiny dogfish specifically, exhibiting jaws and teeth, adaptive immunity, a pressurized circulatory system, thymus, spleen, and a liver comparable to that of humans ( Parton, 2007). Spiny Dogfish exhibit important vertebrae characteristics and an adaptive immune system which makes them an appropriate human model. The ways that they can help with human physiology is with topics such as immunology, genomics, stem cell and cancer, etc.
There are many ways that sharks have contributed to biomedical research, the spiny dogfish are the most used elasmobranch ( Parton, 2007). For example atrial natriuretic peptides isolated from the dogfish heart, have been shown to control sodium chloride excretion from the rectal gland in combination with vasopressin (Silva et al., 1996). They were able to provide a system to regulate chloride secretion in other vertebrates as well as humans. Genome sequence needs to be verified when trying to get an informative framework. The way that they are associated with human function is by getting embryos o f the Spiny Dogfish, and they would supplement the type specific hormone, protein, and collagen. Another thing is that a synthesized steroid mirroring one naturally made by the dogfish shark prevents the buildup of a lethal protein implicated in some neurodegenerative diseases, reports an international research team studying an animal model of Parkinson’s disease (Teber, 2017). Shark cartilage has been used to treat cancer, but effective in treating advanced cancer. The cartilage has not been approved by the FDA and it is not a replacement for medication prescribed by the doctor. There was also a genome study of shark DNA. There are some that have rapid wound healing, and resistance to some cancers. It is tied to their immune system.
Spiny dogfish have unique attributes that separate them from other sharks and perhaps they will contribute more in the future. Biomedical research has helped so many and we will hopefully learn more and move forward with research.
