Scientists are trying to discern the properties of shark skin that make them so impervious to skin cancer. They hope that, when they discover the answer, they can develop lotions or creams that can transfer the same effects to humans.

Scientists and doctors have long been interested in the properties of sharks' bodies, with shark cartilage being used in therapies for cancer, osteoarthritis, psoriasis, and macular degeneration. All such attempts have come with disappointing results for the condition itself and came with financial misappropriation as well as depletion of the shark species.

A study published earlier this month found that various species of fish are suffering from very human-like melanoma. The fish are covered with lesions, scientists believe, as a result of the depleting ozone layer. That study was written by Michael Sweet from Newcastle University in England, in conjunction with various colleagues, and was published in the open-source PLoS One journal.

Meanwhile, sharks' skin has never looked better. When they spend time in the sun, they merely tan – which was startling for researchers to realize in and of itself, because scientists had previously only found evidence of tanning in mammals. Indeed, hammerhead sharks' color changes from light brown to black with time in the sun.

Researchers have attempted to give shark's skin cancer, but to no avail – so scientists set out to discover if sharks were, in fact, tanning. In a study published in the journal Nature, researchers from California State University-Long Beach's Shark Lab conducted an experiment to test if sharks do, in fact, tan. They covered the pectoral fin of sharks caught in the bay with an opaque filter. For 21 days, the sharks were placed in a pond, after which the filter was removed.

The sharks all had a noticeable tan line, affirming that they were actually tanning. After 21 days, their melanin increased by 14 percent; after 215 days, it increased by 28 percent.

Other analyses studying the properties of shark skin have found that it has some amazing properties. In a study that will be published in December in Food Chemistry journal, Phanat Kittiphattanabawon and other colleagues from Thailand and Canada found that the skin of the endangered blacktip sharks was such that it could prevent cooked pork from becoming rancid.

Researchers hope that they can unlock the mysteries of shark skin without killing sharks.