Orcas are renowned for their clever hunting techniques which usually involve a high degree of team work. A very social species, orcas travel around in pods, making it possible to catch prey that may otherwise be difficult or unattainable. Depending on their location and genetic make-up, different communities feed on different prey items, which in turn may require different hunting tactics. Below are some of the known techniques orcas employ to gain a meal.
1. Wave washing
Orcas found in the Antarctic continent have been observed to use a tactic called wave washing. This involves cooperating to create a large wave that washes seals off isolated fragments of ice. To complete the kill, orcas must grab seals by the tail to avoid their snapping jaws. In order to achieve this, orcas may create turbulence in the water through rapid movements in order to off balance the seal. They have also been observed to blow bubbles into the direction of the seal in order to create cover for other whales to sneak up on and grab the tail. The wave washing tactic has also been used to ‘wash’ baby whales of other species away from their mother so a kill can be made.
2. War of attrition
Orcas are known to feed on other whales, particularly calves of species such as grey and minke whale. They have been observed to kill these whales by chasing them for extended periods of time, taking in in turns within the group to lead the hunt which saves energy for each individual. Eventually, once the prey has tired, orcas are able to make their kill either by drowning or bludgeoning whales to death.
3. Shore hunting
Orcas feeding on seals found on the coast employ a simple yet effective tactic for catching their prey. Once they have a target in mind they swim quickly towards their prey remaining just under the surface until the last minute when they burst out of the water and onto the edge of the beach.
4. ‘Carousel feeding’
Orcas feeding on fish such as herring employ a tactic termed the carousel, where they herd fish into compact balls though bubble blowing, belly flashes and tail slapping in order to stun and kill the fish. This is known to occur in Norwegian waters, and is thought to be a preferable hunting technique than catching fish individually which would use up a lot more energy. The term carousel is given to this type of hunting on the basis that the compact ball of fish (also termed bait ball) resembles a rotating carousel.
5. Tonic immobility
Killer whales have been known to induce tonic immobility in prey items such as sharks and sting rays. Tonic immobility is defined as a trance like state some animals enter for unclear reasons. In order to bring on this state in sharks, orcas can force them onto their belly and subsequently suffocate them (sharks need to keep moving in order for water to pass over their gills and oxygen to be takin in). It is thought that tonic immobility can also be induced in rays by inverting them, and New Zealand populations of orca have been seen employing this tactic.
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