Do Sharks Get Sick? Sharks’ Immunity Analysis

Sharks are some of the ocean’s most fearsome predators, thanks to their remarkable immune systems that keep them healthy and strong. However, do sharks get sick? Usually not. But unfortunately, environmental issues such as water pollution or temperature fluctuations have been known to cause illnesses among these creatures in the past.

There are some other factors that you should know about sharks’ immune systems, and here they are.

Do Sharks Get Sick?

Is it true sharks don’t get sick? No, it’s not true. Throughout the centuries, sharks have evolved to possess an incredibly powerful immune system. Therefore, it is highly uncommon for them to become ill. However, they can still experience health issues such as exposure to toxins and bacteria or infection by parasites.

The toxins that can infect a shark come from polluted waters. These toxins can cause various health problems, including skin lesions, liver damage, and neurological disorders.

Different species of sharks may suffer from a variety of diseases, ranging from dermatitis in Basking sharks to inflammation heart disease and herpes in Dusky Sharks. Even more extreme is the viral infection found in leopard sharks that affects their red blood cells. It’s clear that there are serious health risks associated with these creatures!

While bacterial infections are typically uncommon in sharks, there have been several incidents of such afflictions. From meningitis to skin irritations and even neurological illnesses, all seem to be linked back to bacterium infestations within the shark species.

In some cases, Vibrio carchariae – a type of bacterium that triggers meningitis – has been proven contagious amongst sharks, spread through parasites found on their bodies.


Poor bonnethead sharks have a disease named after them. Skin ulcers and severe bleeding are possible outcomes of the fungal infection known as Bonnethead Shark Disease. It affects bonnethead sharks (obviously) and can be fatal to them, but hammerheads are also susceptible to it.

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Also, untreated parasites such as tapeworms and flatworms can cause severe internal damage. The brain-eating single-cell parasite Miamiensis avidus affects smoothhound sharks and many other fish species.

Some of these diseases can be fatal, but most sharks have strong immune systems which help them fight off infections. Sharks also have an efficient digestive system which helps them eliminate parasites and toxins.

Why Is Shark’s Immunity So Strong?

Sharks have a strong immune system that helps them fight diseases and infections. Their immunity is so strong because they have a unique type of blood cell called leucocytes. Leucocytes are able to kill bacteria and other harmful organisms that enter the body, making sharks less likely to get sick.

Also, sharks have high levels of IgM. IgM is an immunoglobulin molecule that helps fight off infections, and the presence of high levels of this molecule makes sharks much more resistant to disease than other animals.

Another factor contributing to the health of sharks is their skin, which naturally produces antimicrobial substances such as squalene and mucopolysaccharides. These substances help to protect the shark’s body from harmful bacteria and viruses, and they also help to keep the skin healthy.

Do Sharks Get Cancer?

A large body of evidence suggests that sharks may have some form of immunity to cancer, but recent research has started to challenge this notion.

Studies conducted by the University of Miami’s Rosenstiel School of Marine and Atmospheric Science in 2012 found that sharks do, in fact, possess some level of protection against cancer. They identified genetic characteristics within their cells, which made them more resilient to forms of cancer than other species.

This was confirmed by a study published in Cancer Research in 2020, which found that the cells taken from shark cartilage had significantly higher levels of gene expression when compared with those from human or mouse cartilage – leading to greater resistance against cancerous cell proliferation.

shark cancer

However, sharks are not completely immune to cancer; it just happens at a much lower rate than in other species. In 2015, researchers identified nine cases where juvenile lemon sharks (Negaprion brevirostris) were diagnosed with neoplastic diseases. This included lymphosarcoma, melanoma, squamous cell carcinoma, and osteosarcoma (bone cancer).

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Moreover, a 2019 study published in Marine Drugs saw scientists document three cases where wild-caught adult white spiny dogfish (Squalus acanthias) suffered from malignant neoplasms (tumors).

The robust body systems seen across shark species also grant them an additional layer of protection against cancers. Sharks possess an adaptive immune system that allows them to recognize and respond quickly to foreign pathogens – including cancerous cells – before they can cause any serious damage.

This process is mediated by genes known as NLRs (nucleotide-binding domain leucine-rich repeat-containing proteins), which are especially abundant within the immune systems of sharks and help suppress tumor growth before it can become out of hand.

Furthermore, certain shark livers produce high concentrations of squalene, a compound known for its anti-cancer properties, such as reducing oxidative stress on cells and aiding in cell repair after tumor formation.

As such, while sharks may not be fully impervious to all forms of cancers, their robust body systems and their inherent genetic protection give them invaluable levels of defense against these deadly diseases.

Do Sharks Die from Cancer?

No, sharks do not typically die from cancer. This is because they have evolved an incredibly strong immune system, which protects them from various cancer forms affecting humans and other animals.

Sharks also possess a unique DNA repair system that helps to prevent damage to their genetic makeup, making them much less prone to developing cancerous mutations in the first place.

Research has shown that sharks contain large amounts of the antioxidant enzyme catalase, which helps protect cells from oxidative damage caused by free radicals.

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In addition, shark tissues contain unusually high concentrations of vitamin A, which can help to reduce cell mutation and combat cell deterioration, further aiding in the prevention of cancer formation.

Studies comparing sharks to other fish species suggest that they are much less likely to contract tumors – a term applied when abnormal cells begin to reproduce rapidly and form masses or lumps within the body – than any other group of fish.

The incidence rate of tumors among shark species is believed to be around 0-3%, compared with 12-20% among bony fish (teleosts). The fact that some sharks can live for centuries suggests that these animals are protected against age-related diseases such as cancer.

Finally, it appears as though cartilaginous fishes may possess a superior ability to fight off carcinogens due to their higher levels of enzymes such as glutathione S-transferase (GST), superoxide dismutase (SOD), and NAD(P)H:quinone oxidoreductase 1 (NQO1).

According to one study, GST activity was significantly higher in cartilaginous fishes compared with bony fishes of all ages examined. This indicates that GST may be involved in protecting these animals from environmental pollutants, which could cause genetic mutations leading to cancer development.


Hopefully, this article has given you a better understanding of whether or not sharks can get sick. Sharks possess several unique evolutionary traits that enable them to fight off disease and protect themselves from developing various forms of cancer.

While there have been a few documented cases of tumors in wild-caught sharks, the incidence rate is still significantly lower when compared with other fish species.

It appears that the combination of unique genes, antioxidants, and vitamins helps to give sharks a strong layer of protection against cancers and other diseases.

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