One of the challenges that dolphins face when hunting for food is that they need oxygen from the air. This means that they can drown if they dive too deep when hunting for their prey.
Dolphins Plan Hunting Dives
Findings of a new study have revealed that these intelligent marine animals, known for their excellent memory and have recently been found to give sponge gifts to their potential mates, use oxygen wisely to survive. One way they do this is by carefully planning their hunting dives.
In the study published in the Journal of Experimental Biology on Wednesday, Feb. 28, Patricia Arranz of the University of La Laguna in Spain and colleagues revealed that the cetaceans use information from previous dives to predict where they can get their food.
The researchers recorded the locations and vocalizations of 37 Risso's dolphins as the creatures swam and hunted for food. Dolphins typically hunt fish and squid.
Small recorders attached to the animals recorded the sound that the dolphins make when they are hunting. Researchers call these buzzes. Arranz explained that these sounds are faster, lower-intensity click sequences that the cetaceans make while attempting to capture a prey.
Dolphins Learn From Past Dives
To find out if the dolphins were planning their dives, the researchers analyzed recordings from 37 dolphin dives while tracking the location of the squid prey. They found that the animals start echolocating soon after they leave the surface.
The researchers also discovered that after the dolphins found success hunting at a particular depth as indicated by their buzzing sounds, the marine animals adjusted the frequency and the echolocation of their clicks to focus on that particular depth during future dives.
"Probably to gain information on the depth distribution and availability of prey and to respond swiftly to rapid changes in habitat structure at different depths," Arranz said.
The cetaceans likewise continued echolocating as they returned to the surface regardless that they were no longer hunting. The animals appear to be already planning ahead, searching for the next location of their next dive.
"Information about prey, learned throughout the dive, was used to plan foraging in the next dive," Arranz and colleagues wrote in their study.
"Our results demonstrate that planning for future dives is modulated by spatial memory derived from multi-modal prey sampling (echoic, visual and capture) during earlier dives."
Other air-breathing sea animals may also have a similar ability.