By Courtney Cooper
The Truth About Cancer in Sharks
Some of you may have heard of the book, “Sharks Don’t Get Cancer” that was published in the early 1990’s, it’s not something that we want to hear, but even sharks get cancer. In fact, scientists have known for over 150 years that sharks get cancer. Cancer in animals has widely been thought of as a myth, however we now know that almost all animals can get cancer. This blog explores cancer in sharks and how busting this myth can help save them. We also discuss further shark facts that you might be interested in! Apex Predators provides the best shark cage diving in Cape Town.
Exploring Cancer in Sharks: Unveiling Nature’s Secrets Beneath the Waves
Despite the title of the popular book, “Sharks Don’t Get Cancer”, the book claims that sharks do get cancer, but only rarely. The authors further claimed that sharks rarely got cancer due to their cartilage containing cancer fighting components that can be used as an effective treatment for cancer in humans. As a consequence, spiny dogfish sharks and hammerhead sharks are fished, and their cartilage is used as an alternative cancer treatment. There is no reliable evidence showing that shark cartilage is an effective cure for cancer.
We now know that sharks do get cancer and they do get sick. There have been tumours found in over 23 different shark species across the world. One of the main reasons as to why sharks are getting cancer is pollution. Scientists have found large quantities of mercury and microplastic amongst other pollutants. In one hour of feeding, whale sharks ingest around 137 piece of plastic in Java, Indonesia. The high levels of mercury in sharks comes from the sharks diverse set of prey. Their prey ingests mercury through algae and sharks are not able to excrete the mercury fast enough.
The below image shows you a cancerous lesion on the jaw of a bull shark, taken in 2010. The shark was observed in a marine reserve over 7 years. Initially the bull shark had a fracture to the lower jaw from a fishing hook. Overtime, the hook passed and what resulted was a growing mass that then formed a tumour.
So why do we not see more sharks with cancer? Well cancer is for the most part an internal disease and when the shark dies, their bodies sink to the bottom of the ocean floor. Just because a shark doesn’t have a visible tumour, doesn’t mean that they aren’t sick with cancer.
In addition to getting cancer, sharks get sick too. They can suffer from bacterial and viral infections and are susceptible to parasites and even tapeworms!
The myth that sharks can be used to treat cancer started in 1970. Henry Brem and Judah Folkman of Johns Hopkins School of Medicine found that cartilage prevented the growth of new blood vessels into tissues. This study was done on a rabbit and not enough evidence was produced to back this theory. From 1970, shark population declined by more than 70% due to overfishing. The population decline can be attributed to the release of this study as drug companies began selling cancer preventative supplements. Not only did the shark populations suffer, but the people also suffered. The public are vulnerable to pseudoscience and these claims have resulted in cancer patients diverting their treatment plans and using in-effective shark cartilage. Unfortunately, you can still buy shark cartilage today in liquid or powder form.
Sharks have survived for over 400 million years, they are ancient! De-bunking the myth that sharks don’t get cancer and that their bodies are not proven to be an effective cancer treatment is crucial to their survival and conservation.
If you enjoyed this article, you may also be interested in our other article, where we discuss the truth about Megalodon. Make your new year exciting. Book your Shark cage diving in Gansbaai.
