In January 2013, NewScientist reported that cetacean researchers following a pod of 400 bottlenose dolphins in the Sea of Japan had observed (and filmed, see the video above) a group of dolphins form a "life raft" to try to rescue an injured pod mate.
The researchers spotted a struggling female, whose pectoral fins appeared to be paralysed. She was wriggling and tipping from side to side. A group of around 12 dolphins came to her aid, crowding around her in the water and diving underwater to support her from beneath.
And then, after about 30 minutes, the dolphins took a remarkable step: they improvised a life raft by huddling close together and lifting the injured dolphin on their backs. By keeping her above water, the dolphins ensured that she did not drown.
Rescuing behaviours such as this are seen only in socially complex animals. In most species, injured or dead animals are soon left behind.