One of the coolest examples of fish geekery apparel has to be this shirt I spotted a few years back at the Science Online 2010 conference in North Carolina, United States. It sports a striking pattern of overlapping silhouettes of hammerhead sharks – and it was worn by, of course, a shark scientist.

David Shiffman is currently a doctoral researcher at the Abess Center for Ecosystem Science and Policy at the University of Miami in Florida, with Neil Hammerschlag and the R.J. Dunlap Marine Conservation Program. Shiffman is studying how marine ecosystems are impacted when shark populations are eliminated.

“This is a very real threat,” says Shiffman. “Scientists have observed population declines of 90 percent or more in some species. Meanwhile, one in six species of sharks, skates and rays are considered Threatened with extinction by the IUCN.”

Shiffman is also an active science communicator. He writes for the marine science blog Southern Fried Science and shares shark biology and conservation news via his Twitter handle @whysharksmatter. He is a leader in encouraging other marine scientists to use social media to enrich scientific discussions and to engage the public.

I asked Shiffman to tell us more about the fish featured on his fantastic shirt — and about why sharks matter to us.

First off, there has to be a story behind this wonderful shirt. Where did you find it?

I’ve always loved Hawaiian shirts, and once bought one off the back of my waiter at Red Lobster — the green one in the photo (see right photo).

This particular shirt, however, was a gift from a student from when I taught a shark biology class at SeaCamp, a marine science camp in the Florida Keys.

What kind of hammerhead shark is on the shirt?

It’s probably Sphyrna lewini, the scalloped hammerhead, because it’s in a school, but it’s hard to tell. To date, scalloped hammerheads are the only large sharks known to form such massive schools. It gets its name from the indented or “scalloped” outline of the front edge of its head.

Tell us more about hammerhead sharks. What are some unexpected aspects about their biology?

Hammerhead sharks are fascinating animals, and are a focus of my lab’s research. In fact, a great hammerhead shark (Sphyrna mokarran) was the first shark I caught on my first sampling trip with the R.J. Dunlap Marine Conservation Program.

I could talk for hours about them (and have), but one thing in particular is important for people to know: hammerhead sharks are particularly vulnerable to fishing mortality. They have one of the most pronounced physiological stress reactions of any species of shark.

This means that simply being caught as bycatch and in sportfishing can severely stress them out — and can be fatal for them, even if fishers release them quickly. When scientists capture hammerheads for tagging and research, we take extra care to let them rest and check on their health before we release them.

As it is your mantra, tell us why sharks matter? Why should people get to know sharks better?

Predators are always important in terms of keeping an ecosystem in balance. Many species of sharks are apex predators, which can be particularly important.

Sharks help regulate the populations of many prey species, and shark population declines have been blamed for trophic cascades that have disrupted commercial fisheries. That is to say, the loss of a predator species can lead to a jump in population in other species, and upset the balance of the food web in that ecosystem.

Sharks also affect ecosystems through what’s called “non-consumptive effects”. You can imagine that if lions were removed from a savannah, gazelles and other creatures might behave differently and gather in places they otherwise wouldn’t. Similarily, the mere presence of sharks can cause prey species to alter behaviors such as feeding location.

When enough prey species move their foraging grounds, the entire ecosystem is impacted. Studying these effects is part of my Ph.D. research at the University of Miami.

At some point we experience an encounter with nature that hits us to the core. What is the most memorable encounter you have had with sharks?

Believe it or not, this was the focus of my college entrance essay, which I still credit for getting into Duke University for my undergraduate degree. In fact, I later participated in a Duke recruitment event (as an alumnus), and the admissions officer used it as an example of a unique essay, completely unaware of the fact that I had written it and was sitting right next to her.

In high school, I had the opportunity to go SCUBA diving in the shark tank at the New Jersey State Aquarium with my dad. The biggest shark in the tank was an 11-foot female sand tiger (Carcharias taurus) with the designation ST-7. During the safety briefing, aquarium staff told us that while most of the sharks weren’t aggressive, ST-7 would often challenge other animals in the tank, including divers. If she started swimming straight towards you, we were told, it was important to just get out of the way.

Predictably, ST-7 started swimming right towards me. Despite my geekiness, I was in many ways a typical teenager, and I thought I was immortal. I held my ground and just kept staring at her. She came extremely close to my face before moving away at pretty close to the last possible second, a moment that was captured in a photograph. In staring contest terminology, I didn’t blink and the big shark did.

I included that photo in my college entrance essay.

Thank you for your time, David.

Sphyrna lewini (Griffith & Smith, 1834)
Scalloped Hammerhead
Click for name etymology (ETYFish Project)
Click for names in other languages (FishBase)

Class Chondrichthyes (Cartilaginous Fishes)
Order Carcharhiniformes (Ground Sharks)
Family Sphyrnidae (Hammerhead Sharks)

FishBase Page: http://fishbase.org/summary/912

— Ben Young Landis