Info: Live underwater webcam showing orcas in British Columbia, Canada. The webcam shows orcas ( Killer Whales ) undertaking " beach rubbing " in the Johnstone Strait.
Johnstone Strait is a 110 km channel along the north east coast of Vancouver Island and is home to approximately 150 orcas during the summer months.
Scientists are still unsure as to why orcas carry out beach rubbing but it seems to be unique amongst northern resident populations, whose habitat ranges from northern Vancouver Island to the waters of southeast Alaska. Family pods of orcas generally return to the same beaches which have a steep incline and loose rounded pebbles. One thought is that it is a social activity providing enjoyment. It is possible that it is a way of removing parasites or it could be that they just like to have a belly rub and massage on the smooth stones.
Despite being called killer whales, orcas are not whales but dolphins and they are the most widely distributed mammals other than humans. They are very adaptable and can live in warm waters near the equator or icy waters of the North and South Pole regions. Generally though, they are most likely found at higher latitudes and near the shore. Orcas do not stay in one area and have been documented traveling long distances. One study found a group of orcas travelling all the way from the waters off Alaska to those near central California, a distance of more than 2,000kms.
Orcas use echolocation to talk to each other and hunt. They will make a sound that travels through the water until sound waves hit an object. Then, the sound wave will bounce back to the orca. Using this technique, they are able to detect where objects and other orcas are in the area. Orcas can also find out the size and shape of an object using echolocation.
Orcas are very social and live in groups called pods, which usually have up to 40 members. There are two different kinds of pods: A resident pod which is less aggressive and tends to prefer feeding on fish and a transient pod which is more aggressive and the orcas work together to hunt down marine mammals.
Orcas are apex predators, at the top of the food chain. Their diet varies depending upon their location and the season but includes fish, walruses, seals, sea lions, penguins, squid, sea turtles, sharks and even other kinds of whales. An average size orca will consume just over 200kgs of food per day.