Smelling Turtles

The smell of bacon sizzling in a frying pan, pizza baking in the oven, or burgers charring on the grill can instantly set the mouth to watering. For young loggerhead turtles, though, it’s the smell of boiling cabbage.

Loggerheads are found all along the Atlantic and Gulf coasts of the United States. They spend almost their entire lives in the water, migrating across thousands of miles. They feed on clams, crabs, mussels, and other shellfish, as well as jellyfish.

A study a few years ago revealed that loggerheads may locate their prey with a good sense of smell. And a follow-up study found that the turtles are particularly attracted to a smell like that of boiling cabbage.

Researchers placed young loggerheads in tanks, and wafted different scents over the tanks – lemon, cinnamon, jasmine, and a cabbagey smell produced by a compound known as dimethyl sulfide. In the oceans, it’s released by algae when they’re being consumed. The turtles were indifferent to the other smells, but spent twice as long sniffing air that was dosed with dimethyl sulfide.

In the open ocean, that smell is common in areas of upwelling. Cold, nutrient-rich waters from the deep rise to the surface, spawning massive blooms of algae. The blooms attract creatures that dine on the algae, including jellyfish. So if a loggerhead smells the aroma of boiling cabbage, it’s a good bet that there’s a plentiful supply of jellyfish – a feast that helps the loggerhead keep going in its long-range journey through the sea.