This blog was written by Dr. David Shiffman, a marine conservation biologist and public science educator based in Washington, D.C. Renowned for his witty social media presence, he has written for the widely-read ocean science blog Southern Fried Science, and his science writing has appeared in publications including the Washington Post, Scientific American, Gizmodo and Scuba Diving Magazine. Follow along with him on Twitter, Facebook and Instagram, and stay tuned his future contributions to the Ocean Conservancy blog.

During my career as a marine conservation biologist and public science educator, I’ve been asked thousands of questions about sharks from people all over the world. I answered one of those questions (“How did you get into this field?”) in an introductory post last month. The following are some of the answers to the questions that I’ve been asked the most often!

What’s the best thing I can do as a concerned citizen to help protect sharks?

Around the globe, many shark species are threatened with extinction, and the single greatest threat facing sharks as a group is overfishing. I’m a strong supporter of well-managed sustainable fisheries, and advise that for most people, the single most effective thing they can do to help the ocean is to purchase and support sustainable seafood options (while not purchasing and supporting unsustainable seafood). You can also educate others on this issue in a polite and respectful manner (remember, no one ever changed their mind by being yelled at by a stranger in a grocery store or seafood restaurant).

Other things you can do to help include donating time or money to research labs working on conservation-relevant shark research or to responsible environmental non-profits like Ocean Conservancy, and sharing accurate information about shark conservation while helping stop the spread of false information or portrayals of sharks on your personal social media feeds and in conversations with friends and family. Climate change and plastic pollution are of course also major problems facing sharks and all other creatures in our ocean, too, so it’s never a bad idea to work to decrease your carbon footprint and reduce your consumption of single-use plastic.

Can you identify this species of shark I saw from a vague description and/or from a blurry photograph that doesn’t show any diagnostic features used to distinguish between species?

No, I can’t, and neither can anyone else. There are a lot of species that look pretty similar, especially the family known as Carcharhinids. Many require a good look at a specific anatomical feature to be sure, while some require a DNA test! A blurry photo almost certainly doesn’t show enough detail to be able to distinguish between many species of sharks, and a vague description of “it was a little smaller than me and brownish-grey” could quite literally be one of over a hundred species. Whenever there’s a viral internet “debate” about what species of shark is shown in a photo, tons of people chime in with some version of “you can tell it’s [species X] because of [something that is absolutely not a distinguishing feature of species X],” and it drives me a bit nuts, because we can really only conjecture without actual evidence or samples. I’m happy to discuss what it might be, but unfortunately can’t typically give a definitive answer.

Since sharks are attracted to blood, should I avoid going into the water if I am bleeding in any way, even just a little bit?

According to my colleague Dr. Tricia Meredith, an expert on the olfactory sense of sharks (aka, their sense of smell), this is not something that you need to worry about. If you are actively bleeding from an injury of some kind, you should probably avoid going in the ocean—not so much because of sharks, but because of the risk of infection.

How many species of sharks have you seen over the course of your career?

Counting SCUBA diving for fun, research expeditions and trips to aquariums, I’ve seen 53 species of sharks. This is a little less than 10% of all the shark species that exist, according to the upcoming edition of the “Sharks of the World” reference guide, so I’ve certainly got a lot more work to do!

What’s your favorite species of shark?

Sandbar shark is #BestShark, in my opinion (follow that hashtag on Twitter and Instagram to learn all about these magnificent sea beasties). Despite having humble morphology without any fancy stripes or spots or extra-long tails or strangely shaped heads, sandbar sharks punch above their weight in both marine biology research and public outreach. They’re one of the most-studied species of sharks (there’s a major nursery area for them near the world’s oldest research shark survey at the Virginia Institute of Marine Science), and they’re one of the most commonly-seen sharks by members of the public because they thrive well in aquariums. This species was also my Master’s study animal, so while they weren’t the first shark species I ever saw, they were the first shark species I ever saw a lot of on purpose.

Have you ever been bitten by a shark? 

I sure haven’t, and I’ve been in the water with hundreds of sharks as well as very near to thousands of sharks on a research vessel. Shark bites are incredibly rare, and more people are killed by lawnmowers and vending machines than by sharks in a typical year.

How can I become a marine biologist?

Glad you asked…stay tuned for a future post focusing on this important question.

Can I ask you more questions about sharks?

You sure can. Follow me on social media @WhySharksMatter, and I’m always happy to answer any questions anyone has about sharks. I do a weekly “ask me anything” session, so feel free to ask then or whenever you’re looking for an answer!