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This is an interesting video about the Elvis Project. ( a project to shed new light on a feeding method for Dolphins)
See video and my transcription.
Further information on the project.
ELVIS system
This is a video about the Elvis system. The objective of this study was to shed new light on a feeding method first observed in wild dolphins on the Little Bahamas banks known as “crater feeding” or benthic feeding.
The ELVIS, which stands for Echo-Location Visualization Integration System, included a 4-by-4 hydrophone matrix mounted on fabric.
A controlled, simulated foraging arena was set up in a pool.
The ELVIS system was buried under a layer of about 5 cm of fine coral sand, and three identical objects (targets) were made from PVC tubing.
Each target was filled with 3 iron nails to make their sonar target strength (the target strength of PVC is known to be very weak). When buried, the PVC tubes filled with water, made a hollow in the sand. This allowed two hypotheses concerning what cues the dolphins might use to find the buried fish in the wild to be tested:
One was the echo of the fish/object itself and the other was the echo of the hollow in the sand created by the fish’s body.
A number of 25 sessions were carried out with three animals (all male) allocated to participate. The preliminary conclusions were that all three dolphins used their sonar intensively when they tried to find the objects, whether they were partly or completely buried in the sand, and that they had obvious problems finding them even under only 5-10 mm of sand.
It is important to mention that these dolphins were inexperienced with sonar seabed exploration. They had never been asked to perform such a task before; instead they had trained to pick up objects on the surface of the seabed, which is an easy task compared to locating buried objects.
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