Dolphins Prove Themselves (Yet Again)

in News
July 25th, 2011

Dolphins are pretty amazing creatures, to put it simply. In Douglas Adams’ The Hitchhiker’s Guide to the Galaxy, the dolphins knew of the Earth’s impending doom well before people did (“So long, and thanks for all the fish!”). In addition to their extraordinary cognitive abilities, they have highly developed and extremely interesting social skills (such as killing for pleasure).

Speaking of killing, let’s discuss sharks. Contrary to popular belief, sharks are only dangerous if you give them reason to be. During the course of my summer internship, I’ve seen many sharks, from toothless dogfish to five foot long juvenile tiger sharks. All have been docile; they tend not to try to attack unless you poke them hard enough (in an out of water case). But, say you happened to be standing in front of the aforementioned tiger shark’s mouth and poked it, and it flailed and bit your leg. You’d probably scream in pain, bleed, and need to see a doctor right away.

Now consider an in water encounter between a dolphin and a shark. The dolphin could just be swimming normally and pass a shark. The shark could misinterpret the dolphin swimming nearby as a threat, and attack, leaving a 3 centimeter deep, 30 centimeter long, 10 centimeter wide wound. Not only would the dolphin not feel pain from this, but it would continue feeding, swimming, and behaving normally! Even more amazingly, the wound would heal over time with little scarring or changes in overall contour!

Example of wound healing in a bottlenose dolphin

Wound healing over time in a bottlenose dolphin

Example of dolphin wound healing

Wound healing over time in a bottlenose dolphin

A recent study by Zasloff investigated the remarkable healing process in bottlenose dolphins. Though little is known about the pain reflexes in dolphins, it has been shown that they will withdraw when pricked. In response to long lasting wounds caused by shark attacks, dolphins have been observed to exhibit normal swimming and feeding behaviors in as little as two days after the attack. They do not seem protective of their wounds in the slightest either. What is it about the dolphin’s pain circuits allows them to seemingly ignore serious wounds?

The biological and biochemical healing process is likely due to special adaptations resulting from a marine lifestyle. Dolphin wounds may be less likely to bleed due to a diving reflex adaptation. When diving, dolphins divert their blood supply to their inner vital organs, allowing them to spend longer periods of time underwater. This reflex might also come into effect after sustaining a traumatic wound. However, what makes the process truly remarkable is that it mimics the process of regeneration. Just like a starfish can regrow an arm, this process allows deep wounds to heal almost flawlessly in dolphins. Blubber invades the wound and repairs the tissue with the already existing blubber structure. In addition, blubber contains both natural organohalogens and short chain fatty acids known as isovaleric acids, both of which serve as antibacterial agents. Given the amount of bacteria in the marine environment, these must be extremely effective against preventing infection in the wound.

Not meaning to wish harm on dolphins, but studying their wound healing process could give tremendous insight into how humans can successfully manage injuries. We could potentially produce numerous new painkillers or antibiotics if we found the right chemicals in dolphins. Studying the regeneration-like healing may lead to new discoveries in stem cell research. Though we probably still will not be able to regrow limbs, the field has immense potential in treating localized but serious wound injuries.

Observations on the Remarkable (and Mysterious) Wound-Healing Process of the Bottlenose Dolphin : Letter to the Editor, Journal of Investigative Dermatology

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