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Shark Education: Meet Biologist Joshua Moyer


Joshua Moyer is a biologist specializing in elasmobranch fishes (sharks, skates, and rays). After completing his Bachelors of Science with Departmental Honors in Biology at Millersville University of Pennsylvania, Joshua earned his Masters of Science from Cornell University, where he studied the comparative anatomy of the jaws and teeth of White Sharks and their relatives. Joshua has co-authored several papers on shark dentitions and routinely lectures in college courses in marine biology, evolution, and vertebrate anatomy. A member of the American Society of Ichthyologists and Herpetologists (ASIH) and the American Elasmobranch Society (AES), Joshua enjoys visiting shark localities wherever they may be and working with the many fascinating people who share his love of these fascinating fishes. We are excited to share Joshua’s shark story with you. You can also check out Joshua’s most recent publication about shark teeth HERE To follow Joshua’s work you can check out TWITTER


1. What is your favorite shark and why? That’s a tough question. If I had to choose just one shark species it would be the smooth dogfish shark, Mustelus canis. It’s a coastal shark that feeds mostly on invertebrates and small fishes, and it doesn’t get much larger than four feet in length. When I was a little kid, my parents would take me to the beach in New Jersey during the summer. I used to love watching the fishermen, and they would often catch smooth dogfish. Even as a little kid I’d rush over to make sure that the shark was being released, and then I would ask if I could let it go. The fishermen would often agree, and I would walk the shark out into the water and watch it swim away. Those sharks were just so beautiful! 2. Why did you decide to try CT scans on sharks? What were you hoping to see? Several years ago I was helping to teach a shark biology course at Shoals Marine Laboratory with Willy Bemis, a professor at Cornell University. He showed me amazing X-ray computed tomography (CT) 3D reconstructions of all sorts of specimens that were generated in the Cornell Biotechnology Resource Center. When we started researching shark teeth together we agreed that we should scan some teeth and jaws to investigate questions like “what tissues are shark teeth made out of, are all shark teeth made of the same tissues, and how do different shark teeth grow and develop”.

One of the best things Willy ever did for me was to have me read Samuel Scudder’s essay “In the Laboratory With Agassiz” from 1874 (later re-titled “Look at Your Fish”) in which Scudder describes training under the famed biologist Louis Agassiz. Agassiz lays a fish in front of Scudder and leaves him there for hours to look at the fish, observing every detail of the animal. Scudder grows tired of this quickly, but Agassiz tells him to continue looking at the fish for the rest of the day. By the end of the hours that Scudder spent looking at the fish, he was observing details that he had not previously seen or appreciated. The chance to use CT imaging in our work gives me the opportunity to follow in Scudder’s footsteps and look at my fish, in this case sharks, in a new and fascinating way to see things I haven’t seen or perhaps wouldn’t have seen using conventional methods! 3. Can you explain the process of scanning the animal? The first thing we do is select our specimen, usually from a museum collection. When you CT scan a specimen, whether it is a plant or a dog or a shark or anything else, you place it between an X-ray emitter and an X-ray detector. An X-ray is taken and then the detector and emitter move just a little bit to a new position so the next X-ray is taken from a slightly different angle. In some CT machines, the emitter and detector rotate around the patient or specimen, and in others the specimen actually sits on a stand that rotates in the X-ray field. Either way, what you get is a series of X-rays, each taken in a known order from a known angle, and we can use computers to arrange those X-ray images and reconstruct three-dimensional virtual models in which all the tissues of different densities appear according to a color gradient. For example, I could tell the computer to show me all the hard tissues, like the enameloid of shark teeth, in white and all the soft tissue, like the gum tissue in dark red. 4. What is one shark you would like to see in the wild? I’ve seen a variety of shark species in the wild, but one that I haven’t seen yet and always wanted to see in the wild is the Greenland Shark, Somniosus microcephalus. Those things are just so cool, and they can get big! Greenland Sharks can grow up to 20 feet long! Some Greenland Sharks have been found with marine mammals, like seals, in their stomachs, but if you ever saw one of these sharks, they move so slowly you’d have to ask yourself what kind of hunting strategy they’d use to catch a seal. 5. Why is incorporating scans into shark research a critical component to better understand them? The more ways you have to look at the world around you, the easier it is for you to learn about and understand it. The CT scanning that Willy and I do as part of our research gives us another way to look at the sharks we study. Every time you look at a shark, you should try viewing it as many different ways as possible. The greater the variety of ways that you can look at something, the greater your chances of learning something new, and learning about sharks is the first step in understanding and appreciating them.

6. What is the most challenging part of your research? The most challenging part (and sometimes the most fun part too) of the research we do is the background research. A good shark scientist has to know their way around libraries and Internet databases. People have been looking at and describing shark teeth for a long time. A lot of what has been said about shark teeth are good observations, but some times we find other observations that are way off the mark! For example, it wasn’t until the middle of the 1600s that Nicolas Steno saw the similarities between fossilized shark teeth and the teeth in the head of a large shark brought in by local fishermen. Until then, many people thought fossil shark teeth were the fossilized tongues of snakes or dragons! Tracking down and sorting through all the literature that has been written about sharks can be challenging, but it reminds me that I am part of carrying on a very old tradition of studying these amazing animals!

7. What is a typical day at your job like? A typical day for me starts with going to the lab where I read any scientific articles that may have come out recently and file them away for possible reference later. Then I write about or illustrate what I am studying, and on some days I’m lucky enough to work with students who share my passion for sharks. We might dissect a shark or review shark literature together. Then depending on what day of the week it is, I may go lecture in a class or I may take some time to organize our growing collection of shark jaws and teeth, which I always enjoy doing! Some times I’m lucky enough to take trips to visit friends and colleagues around the country to work with them for a little while. Or I may go to a conference to meet other shark lovers and present the findings of whatever research I may be involved in.

8. Do you think scans can help change public perception of sharks? I think that any technology that lets people see something they thought they knew in a different way could change public perception. When I show someone a detailed reconstruction of a CT scan, whether it is of a whole shark or a single tooth, they always stop and stare at it, and every person I’ve ever shown a shark scan to has asked me questions. It stokes their curiosity, and curiosity is a great thing to bring out in people. When people are focused on learning something new, they tend to forget their preconceived notions and what they thought they knew. And getting people to forget what they thought they knew and showing them all the things they have yet to learn is a great place to start changing any negative public perception of sharks. 9. In doing CT scans on sharks has anything surprised you with the images/findings? Oh yes! I just presented a paper at the annual meeting of the American Society of Ichthyologists and Herpetologists describing a misconception about the tissue composition of White Shark teeth that has held on in the literature for over 80 years. Willy and I had been looking at CT scans of White Shark teeth, and I remember very clearly him turning to me and remarking that what we were seeing wasn’t matching many of the classic illustrations of shark teeth that we’re used to seeing in text books. It was our CT work that kick-started that project, which was published earlier this year in the Journal of Morphology, and we continue to apply this technology to other species of sharks. We’re currently working on some projects with CT reconstructions that are really beautiful and will help to inform our understanding of shark tooth replacement!

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