Filling a lecture hall at the College of Charleston‘s Harbor Walk Campus, excited adults, college students and shark-enthusiasts were greeted by the South Carolina Aquarium’s Director of Education, Brian Thill, who presented the theme for the fourth session of the Aquarium’s Holland Lifelong Learning series. The audience was about to take a journey through the incredible evolution of shark and ray species.
Described as perhaps a combination of Ancestry.com and CSI, the evening’s presentation highlighted the work of Dr. Gavin Naylor, a College of Charleston Biology Professor. Dr. Naylor and his colleagues seek to explore all species of sharks and rays down to their individual strands of DNA. Their work aims to answer questions about which species are related, where they live and if their populations are stable. Dr. Naylor and his team have defined over 1,100 different species through a combination of scientific illustrations, CT scans, and DNA. CT scans help create 3D images that have provided crucial behavioral information. For example, a lemon shark CT scan depicted a fish swallowed headfirst, before it could even think to swim away! But what is the importance behind that CT scan, you may ask? With just that bit of information revealed in the scan, it could determine that lemon sharks demonstrate an ambush predatory style for catching prey.
The phylogenetic tree Dr. Naylor recounts isn’t all that different from our own family trees. We all have that uncle that will never grow up, a world-traveling sibling, the fashionable aunt, and those cousins that we just can’t explain.
This information, along with a myriad of additional data, is compiled onto a website, http://www.sharksrays.org. This website acts as a dynamic resource for any user, whether you want to create your own shark field guide, inform regulatory agencies on the population size and stability of certain species, etc.
Although researchers have been investigating sharks’ unique lineage for some time, they continue to expose more unique identifiers. Just last year, researchers discovered a shark species that can live for nearly 400 years. “Imagine a 99 year old tween,” Dr. Naylor joked. Dr. Naylor also spoke about the transatlantic journey of great white sharks, camouflaging capabilities of certain species by the use of photophores to emit surface light through their underside, and even the discovery of “virgin birth”, or parthenogenesis, in sharks.
Scientist are in the midst of uncovering some of the things that these animals can do, but “shouldn’t be able to do” that help them survive. A few of these adaptations have been realized and even patented. By literally “scratching the surface”, innovators have been able to patent goods and products that mimic the external skin of sharks. Dermal denticles, or modified teeth, cover shark’s bodies and limit the growth of algae and sessile animals, a trait that can be mimicked for a myriad of uses. Anti-fouling paints intended for the bottom of boats prevent hitchhiking animals from attaching. Speedo® fast skin swimsuits, originally designed to help swimmers remain streamlined through the water, are now banned from competition because so many records were broken. Even hospital surfaces may soon be covered with a micro pattern to reduce the spread of bacteria. All of these products exist just from examining the surface of shark anatomy – we can only imagine what we haven’t discovered yet by studying the incredible compositions and adaptations of these animals.
Through all examples, Dr. Naylor presents species that should, in theory, be labeled as fragile and prone to extinction. In part, this idea is due to their long life spans, age of maturity, and gestation periods. When they do reproduce, most species go through an energy intensive process that yields few pups. A great example of this is found in sand tiger sharks – females develop up to 20 pups in utero, but siblings will kill each other yielding only one victor.
Resilient shark species have survived two major extinctions in history, the Permian and Cretaceous, and have even thrived afterwards by adapting to the changing environment. Now, their lineage could be at risk due to impact from human beings. Dr. Naylor cautioned the group, “It’s not necessarily the severity of human actions, but the scope. We’re leaving no place untouched. The key is to focus on education and understanding how our lives depend on nature. We’re only starting to realize the potential of these animals.” Dr. Naylor concluded, “The more we look, the more we find.”
Interested in attending another Holland Lifelong Learning event? Join us at the next installment, “Blue Mind: Water For Your Well-being”. Featuring marine biologist and bestselling author Dr. Wallace J. Nichols, learn about the health benefits of being in, on, under, or simply near water, and the neuroscience behind it all. Holland Lifelong Learning is made possible by the generous support of Mary and Mason Holland and their commitment to the Watershed Campaign.