Curious by Nature

UM marine researcher studies the curious and mysterious tiger shark, which resides at the top of the food chain.

By Peter E. Howard
UM News

MIAMI, Fla. (January 16, 2014) — When Neil Hammerschlag jumped into the waters off the Bahamas in search of the elusive tiger shark, his hair was bubbling with the froth of shampoo.

In the live-aboard boat shower when a crewmate shouted, “tiger shark!” Hammerschlag grabbed his fins, wetsuit, mask, camera, and vaulted into the ocean – research first. The huge shark, which rules the top of the food chain, circled the University of Miami assistant professor and his locks of tight curly hair.

The mammoth beast inched closer, opened its colossal jaws that provided an intriguing glimpse of the animal’s innards. It rotated slowly to the side, putting one of its eyes squarely on Hammerschlag. It circled again and came back toward him. Mouth open, serrated teeth gleaming.

“I decided this might be a good time to get back on the boat,” he said.

“Neil
 

That was 11 years ago and his first encounter with a tiger shark. Thursday night, in the auditorium at the UM Rosenstiel School of Marine and Atmospheric Science on Virginia Key, Hammerschlag delivered a captivating lecture about the tiger shark to a standing-room-only crowd.

The director of the R.J. Dunlap Marine Conservation Program described the work he and others are doing to learn more about, and help protect the mysterious tiger shark, which can grow to 18 feet in length and weigh more than a ton. They are, Hammerschlag said, “the biggest, baddest animal in the ocean,” and at birth are 30-inches long and eating small fish, graduating to lobster, sea birds, dolphins, sea turtles and smaller sharks.

On occasion these feared creatures dine on weird bits of fare, including tires, boots, bags of coal, and explosives they scavenge from the ocean depths. Oh, they have also been known to eat a tourist or two. About anything that enters the ocean, Hammerschlag said, has a chance of being tagged as food.

“Tiger sharks are curious animals,” he said.

Thursday’s talk was the kickoff to, Sea Secrets: Exploring Our Oceans 2014, a lecture series that continues into May and includes talks about ocean conservation, sea level rise and the use of art to inspire conservation. The series is presented by the Rosensteil School and The Ocean Research and Education Foundation.

Hammerschlag walked the audience through the life cycle of the tiger shark, and shared a few things that are known about them: They have great eyesight and see in color; they hear very well; and can sense low frequency sounds and vibrations in water.

Tiger sharks are found throughout the world, the females give birth every three years or so to a litter of 50 pups or more. During mating, the male sharks often bite fleeing females to hold them in place, Hammerschlag said, noting that the skin of the female tiger shark has evolved thicker than the males to protect them from the bites.

Over the years, Hammerschlag and his team have tagged tiger sharks with satellite tags on the dorsal fin, or an internal tag that emits a pulse that is tracked by underwater hydrophones deployed off South Florida’s coast. The tagging process has helped researchers learn about migratory patterns (migrations appear to follow the path of the Gulf Stream), and areas where tiger sharks mate.

Hammerschlag has also started a program to expose students to tagging and shark research. More than 1,500 students have been involved.

About 90 percent of the time, Hammerschlag said, tiger sharks swim less than 20 meters deep. But the animals have been known to dive as deep as 400 meters, but the reason for that remains unknown.

Their only predators are human. They are hunted for both commercial fishing and sport, and there are efforts underway to minimize shark fishing and expand protected waterways where it’s known tiger sharks migrate and breed.

“Neil
 

Hammerschlag sprinkled Thursday’s lecture with photographs and video clips of him and others in the water with the animals. So, how do researchers stay safe while learning about tiger sharks?

The sharks are “ambush predators” that like to sneak up on prey, so if they can see you and you can see them, you are probably safe in the water with them. But, if he gets a bad feeling about a particular shark, or feels threatened, Hammerschlag has a well thought out plan on how to deal with the situation.

“I get out of the water,” he said, matter of fact.

Peter Howard can be reached at 305-284-8085


Share it with others
« Back to News Releases
News story figure

University of Miami Media Contact:

Contact Person:
UM Communications
Person role:
Organization:
Phone:
Email:
umcommunications@miami.edu

University of Miami’s mission is to educate and nurture students, to create knowledge, and to provide service to our community and beyond. Committed to excellence and proud of our diversity of our University family, we strive to develop future leaders of our nation and the world.