Dolphins Using Tools to Hunt
Posted on December 10, 2008 Comments (6)
Cool open access research from PLoS One, Why Do Dolphins Carry Sponges?
We compared sponge-carrying (sponger) females to non-sponge-carrying (non-sponger) females and show that spongers were more solitary, spent more time in deep water channel habitats, dived for longer durations, and devoted more time to foraging than non-spongers; and, even with these potential proximate costs, calving success of sponger females was not significantly different from non-spongers. We also show a clear female-bias in the ontogeny of sponging. With a solitary lifestyle, specialization, and high foraging demands, spongers used tools more than any non-human animal. We suggest that the ecological, social, and developmental mechanisms involved likely (1) help explain the high intrapopulation variation in female behaviour, (2) indicate tradeoffs (e.g., time allocation) between ecological and social factors and, (3) constrain the spread of this innovation to primarily vertical transmission.
The dolphins use the sponge to push along the ocean floor and disturb fish, that are hidden. Once the fish start swimming away the dolphin abandons the sponge and catches and eats the fish. Then the dolphin goes back and gets the sponge and continues.