Sharks are known to have a keen sense of smell, which in many species is critical for finding food. However, according to new research from Boston University marine biologists, sharks can not use just their noses to locate prey; they also need their skin – specifically a location called the lateral line. The lateral line is an organ used by all fish to detect, with exquisite sensitivity, movement and vibration in the surrounding water. According to the research team, this is similar to how humans can sense air flow with the small hairs on the face. Until now, it had not been demonstrated that the lateral line also aids in the tracking of odor plumes.
"Odor plumes are complex, dynamic, three-dimensional structures used by many animal species to locate food, mates, and home sites. However, odor itself has no directional properties, so animals must use a variety of senses to get the directional information for a smell," said Jelle Atema, professor of biology at Boston University and study co-author.
The new study examined the contribution of the olfactory system, the lateral line, and vision in odor source detection and localization in the smooth dogfish shark. The results, which appear in the June 1 issue of the Journal of Experimental Biology, show that this shark is severely handicapped in its ability to locate the source of an odor when deprived of information from its lateral line, particularly in the dark.
According to Atema, since most odor plumes disperse in patches, fish locate odor sources through a process referred to as "eddy chemotaxis," or the tracking of odor and turbulence simultaneously.
"We might see odor and turbulent eddies in the oily wake behind a boat. A moving animal, similarly, leaves behind a trail of turbulent eddies flavored by its body odor," explained Atema. In an eight meter flume in the lab, Atema and Jayne Gardiner, a recently graduated Boston University Marine Program (BUMP) Masters student a