WHOI's Peter Tyack and other scientists kept track of some of the beaked whales like this by means of a Dtag. The novel archival tag has been developed to monitor the behavior of marine mammals, and their response to sound, continuously throughout the dive cycle. The tag contains a large array of solid-state memory and records continuously from a built-in hydrophone and suite of sensors. (Photo by Todd Pusser, taken under NMFS permit 14241)