Unbeknownst to me until very recently, July 14th was Shark and Ray Awareness Day! In honor of these amazing elasmobranchs, I have decided to write a little about this cool group of cartilaginous fishes! Around the time of Shark and Ray Awareness Day, I decided that it would be as good a time as any to reach out to my friend Elana Rusnak, a shark biologist who started her master’s research on sharks at the same time I started my own research on Fish Aggregating Devices at the University of Miami Rosenstiel School of Marine and Atmospheric Science in 2017. Although we focused on different research topics, we’ve had a great few years talking about everything from the ocean to our shared love of punk rock music to the joys of rollerblading! It was really exciting to talk to her about her work for the purpose of sharing information about some of the coolest fishes swimming! Shark photos by Stephen Trbovich. Because of movies like Jaws and The Shallows, sharks and their brethren get a bad reputation, so I brought in Elana to talk to This Blog Is Trash a little about sharks and how she got to work with them for her career! Shark Facts with Elana: Elana and me at the Wetlab in our matching Great White Shark Socks. To start: sharks and rays are cartilaginous fish belonging to the scientific group Chondrichthyes, which means that instead of ossified (or calcium-rich) bones like you and I have, they have bone structure made of cartilage (which we have in our ears and noses!!!). There is incredible shark and ray diversity in the oceans – they’ve been around for 450 million years – which makes them older than TREES!! Elana’s favorite shark is the nurse shark (Ginglymostoma cirratum) - in part because they’re just so darn cute and because they’re low key SO COOL. When most people think of nurse sharks, they think of them laying on the bottom of the ocean, which Elana admitted is essentially what they do, but she also says that they’re practically indestructible. They’re really tough and just hang out on the seafloor essentially straight vibing. Nurse shark photo by Matthew Bernanke. While we were talking, Elana also shared with me some amazing fun facts about my favorite shark, which is of course, the whale shark (Rhincodon typus), which is THE BIGGEST FISH IN THE OCEAN, growing up to 18 and 19 meters long or about 60 feet long!!! They can sustain this because they eat KRILL which are very small animals that live at the surface! Whale sharks are usually nocturnal and often feed vertically with lots of tiny teeth that point in towards their throat to trap their prey. Each whale shark pattern is unique to each individual - just like zebra stripes! In addition to being uniquely identifiable, they live for a really long time too! Here's a picture of me with my favorite shark...in Animal Crossing New Horizons on my Switch. When asked what were some common misconceptions about sharks, she responded: “I think sharks are kind of portrayed as mindless killers when really they’re mindful killers.” After a small chuckle, she explained what she meant - sharks are smart and they’re curious, and the only tool they really have to explore the world is with their mouths, so that’s what they use. Sharks aren’t killers, they’re predators in their natural environment, and when it comes to eating, sharks are like us - they have taste buds and preferred foods, some like octopuses (like catsharks), and others like seals and sea lions (like great whites). Elana wants to remind everyone that sharks don’t infest waters - they live there! As a reminder to beach and ocean goers, Elana wanted to reinforce that “sharks should not be feared but they should be respected.” Elana also wanted to dispel a common misconception that sharks can smell a drop of blood a mile away. She says that while this misconconception is based in fact, it has to do more with the fact that the strongest sense a shark has is chemoreception, which is similar to the way we use our noses to smell. In order for the sharks to pick up on smell it has to reach them, usually via dispersal due to water movement. Something that is really nifty about their sense of smell is that they can smell in stereo! We humans hear in stereo - for example if you were to close your eyes and someone were to snap their fingers, you would know which direction it was coming from - and sharks can do that with SMELL!!! How cool is that? Sharks have an incredibly keen sense of smell and can pick up on extremely low chemical concentrations - somewhere between 1 in 1,000 and 1 in 1,000,000 depending on species. This is the reason people say they can smell a drop of blood a mile away - it’s not instantaneous, but in a large volume of water they would be able to pick up on very few molecules of that smell reaching them and would be able to track it to the source using their stereo olfaction. And while this could be a potentially scary factoid, science has found that sharks aren’t really all that attracted to human blood, they respond more to blood from fish and crustaceans - their normal prey. Sharks have social hierarchies and behaviors - in the shark world, if you’re bigger that means you’re the boss. They are usually sexually dimorphic (meaning that males and females look different) and in general, mature female sharks are larger. That said, there are over 500 species of shark, and most of them are small! The smallest shark is the dwarf lanternshark (Etmopterus perryi) which is only 6 inches long when fully grown! So now that we all agree that sharks are excellent - what is going on with them in the oceans? According to Elana (and my own field of fisheries science), sharks are being overfished, so they are well below their natural levels in the ecosystem, but thanks to increasing knowledge and education, some shark populations are on the rise! This is a good thing for our oceans because we need sharks as an important part of the balance in the ecosystem as mid- and high-level predators. What are sharks fished for - is it fear alone? No we actually harvest sharks for their meat, their fins, and their oily livers (which they use for buoyancy instead of an air-filled swim bladder found in other fish). The oil from their liver is called squalene and is used in lots of different products including cosmetics, however the use of squalene is contributing to overharvesting. In order to help sharks, Elana recommends education: learning about the relationship they have with the environment, and the relationship you can and should have with them. In order to help prevent further overfishing of sharks for their squalene oil, Elana recommends shopping vegan and/or avoiding products with squalene in them. So who is Elana Rusnak, and how did she get to be a shark expert? Elana grew up on the shores of Lake Michigan in the Windy City, Chicago and found her way to marine science in a similar way to me – she grew up going to the beach and absolutely fell in love. Having spent time at the Shedd Aquarium (which does BOSS research btw), Elana also spent time on the Jersey Shore with her grandparents. When asked how she found her way to the marine science path, Elana responded with a common theme that I’ve encountered from fellow marine scientists: “I had never really decided what I wanted to do – we all know how broad Marine Biology is.” A huge part of the separation that I feel scientists have from the average non-scientist is the ultra sterile image that scientists are presented as in the media, and I think it’s important to show the world that we are normal(ish) just like everyone else and above that, we just love our jobs and our research. So how does one go from loving the ocean and going to the aquarium to a full-fledged scientist? In Elana’s case, she went on high school trips with Broadreach and Odyssey Expeditions in the Caribbean and absolutely fell in love with sharks. From there it was all about getting into a shark research lab in college which led her directly to the University of Miami. Shark research is pretty tough to get into however. Elana spent every semester for her first five semesters at UM trying to get a position in the RSMAS Shark Research and Conservation Program, finally achieving her goal during her junior year of college. Upon graduating from the University of Miami, Elana applied to be a master’s student in the SRC and was not initially accepted, as the position was for shark movement ecology, which she later realized would not have been a good fit for her (silver linings!). She instead found herself being offered a spot in a master’s program on shark eco-immunology, and jumped at the opportunity. The first thing Elana wants you to know about her research is that “shark immunology is dope!” Sharks have incredibly robust immune systems that contribute greatly to their overall health – just like people! For the basics of immunology there are two systems we need to consider: the innate and adaptive immune systems. Innate immunity is a nonspecific response that fights pathogens and adaptive immunity is the part of our immune system that learns what pathogens look like and is able to mount an immune response more quickly and efficiently the second time a pathogen is encountered - this is why vaccines work! Sharks are the most ancient animal that have an innate and adaptive immune system comparable to mammals - as such sharks have been used as immune models for humans! The reason Elana is so excited about shark immunology is because our scientific knowledge of the shark immune system is relatively limited. Let’s dive into Elana’s research! Elana taking a blood sample on a nurse shark (photo courtesy of Elana Rusnak). Elana’s research was separated into two parts. The first part of her research was studying a specific protein - C-reactive Protein or CRP - that has a naturally low baseline (meaning that there are relatively low concentrations of the protein in an mammal’s blood normally) which skyrockets during an infection and drops back off once the infection has run its course. Cool, right?! Elana spent 2 years looking for the CRP gene in nurse shark liver tissue RNA and DNA. For this part of her project all she could conclude was that CRP is present in the nurse shark genome but was not able to conclude that it acts in the same way during an inflammatory response in sharks as it does in mammals. Elana said of her work on CRP: “It took me 2 years to get the CRP result and 99% failure - that’s a really important part of science. Trying something and failing.” The second part of Elana’s research was looking at transcriptomes, which detail the active cellular and protein processes occurring in that part of the body at the time of sampling. For this project, she had the novel opportunity to look at a sick and healthy nurse shark’s liver transcriptome to compare the two. In order to compare them, she built the transcriptome and looked at the differences in gene expression between the two sharks. In order to understand what was happening in these different sharks, Elana used gene matches from genetic databases (which are apparently out there like little libraries for genomes!!!) and found that the genes and proteins from the complement pathways were really active, which shows that the complement pathway is a fundamental part of the shark immune system! The complement system is a part of innate immunity that functions to clear infection in the host by boring a hole into the pathogen’s cell wall, causing it to burst open and die. Conveniently, this is Elana’s favorite part of the immune system, and she’s really looking forward to learning more about this process in sharks! Elana’s research has contributed to a greater understanding of the role different genes play in shark immunity, and she hopes to pursue a PhD learning more about shark or other fish eco-immunology. You can see Elana giving a lecture about obscure sharks as part of an online series with Broadreach here. Connect with Elana on Instagram: @elasmo_elana or Linked in: https://www.linkedin.com/in/elana-rusnak-marine-bio/ Elana Rusnak recently completed her MSc degree in Marine Biology and Ecology at the Rosenstiel School of Marine and Atmospheric Science at the University of Miami. She worked both as an undergraduate and a graduate researcher in the Shark Research and Conservation (SRC) program for 4.5 years. Her work focused on the immunobiology of the nurse shark (her favorite!). She was able to isolate some potentially important immune genes for the first time, and learned more about what an immune response looks like in a sick shark's liver! She hopes to continue on and get a PhD in the field of Eco-immunology, where the immune function of an organism, like a shark or a bony fish, is related to how it interacts with its natural environment (ecology). Elana loves to teach and would like to become a university professor after she completes her doctorate.
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AuthorBree Gibbs, here. I'm a recent Master's Grad just trying to share what it's like to be a trash scientist (for those who aren't in the know, I'm a marine biologist). Categories
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