A Torrent of Crabs Running to the Sea: A Student Uncovers the Natural History of a Little-Known Species

Article excerpt



Joanna Gyory's Ph.D. plans changed completely when she saw the crabs. It was her third or fourth day at the Liquid Jungle Lab, a research facility on an undeveloped island off Panama's Pacific coast.

After a dry season lasting several months, it started to rain. After the rain, like a scene from a 1950s science-fiction movie, mobs of bright red-and-purple crabs emerged and ran down to the shoreline, swarming over the entire beach, crawling over rocks and anything else in the way.

"I had no idea these crabs even existed, and then all of a sudden there were thousands of them, all running down towards the water!" she said. "And they are bright red. They're very visually striking. It was a feeling of wonder. This was so interesting that I wanted to figure out who they were and what they were doing."

The crabs, Gecarcinus quadratus ("square land crab") are about 4 inches from claw to claw. They are abundant along Pacific coasts from Mexico to Peru. Local residents certainly knew about them, and Gyory, a native Spanish speaker, got tips from them. They told her they saw the crabs in the rainy season. They also told her where she could find them, what the crabs ate, and that people sometimes ate the crabs.


The brilliantly colored adults had been described and named in 1853, but a search of scientific papers told Gyory that no one knew anything about the life cycle of the species--how it reproduces and how it develops from an egg in the ocean to an adult crab on land.

"The coasts of Central and South America in particular have not been studied nearly as well as temperate ecosystems in the Northern Hemisphere, and many species are still unknown to science," she said.

Every year, scientists find hundreds of previously unknown species. Discovering them is the easy part. The next step--learning the species' behaviors and the roles they play in their surroundings--requires painstaking, time-consuming observation, which sometimes isn't done for more than a hundred years.

This branch of science, known as natural history, may seem like a quaint relic from the era of Charles Darwin in the 1800s. Not so, Gyory said. "Natural history is important in the 21st century. We humans are rapidly altering the environment on a global scale without understanding how it might affect organisms and their interactions with their environment."

Gyory had found her Ph.D. project: to uncover the life history of Gecarcinus quadratus.

Called to the tropical ocean

Gyory was born in Venezuela and lived there her first 10 years, and then moved to Miami with her family--her father, an architect, her mother, a teacher, and her two brothers. In one way, she was already preparing to study marine crustaceans.

"In Venezuela my family would take trips almost every weekend to the beach, and I remember running around looking at logs with barnacles all over them, trying to figure out what all those animals were," she said.


She studied biology at Cornell, then worked at the University of Miami, where she read a study by Woods Hole Oceanographic Institution biologist Jesus Pineda. It was about how marine larvae are moved around by currents and waves, and it intrigued her. She went on to earn a master's degree in marine and atmospheric science at Stony Brook University, and when it came time to pursue a Ph.D., "I thought Jesus's paper was so interesting that I really wanted to come work with him," she said, "so I decided I would apply to the MIT/WHOI Joint Program." Pineda became her advisor.

Pineda studies internal waves--waves moving within the ocean, beneath the surface--and how they transport and distribute marine larvae and other animal plankton along coasts. Gyory had planned to study how internal waves affect zooplankton off the coast of the Liquid Jungle Lab. …


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