I Know a Whale Joke: It’s a Real Killer.
Orcas, commonly known as “Killer Whales” are the most distinctive of all cetaceans. Their black bodies with white patches on the underbelly and around the eyes gives these mammals some of the most recognisable markings across the oceans. These majestic creatures are found mainly around the Arctic and Antarctic, however they can be found in most oceans and are also known to travel long migrations. A study showed that the Orcas tended to follow their stomachs instead of normal migratory patterns, allowing them to return to a specific area after the fish stocks have replenished.
Although they are named “Killer Whales”, Orcas are actually dolphins.
The Killer Whale can reach sizes of nearly 10m and weigh up to 9 tonnes. Like most mammals, Killer Whales are warm blooded, with internal temperatures of 36.4°C – 38ºC, close to that of humans. Due to living in such cold conditions within the Arctic and Antarctic, this poses a threat for heat loss, but luckily the Killer Whale has a low surface to volume ratio, as well as a thick layer of blubber to help reduce any unnecessary heat loss. They have been known to dive to depths of up to 300m.
The diet of the Orca is a carnivorous diet; it feeds upon a range of different organisms from sea birds to dugongs and other large marine mammals such as seals.
The streamlined body of the Killer Whale can allow them to swim up to 30mph, however, they normally bumble along at around 4mph. Orcas travel in large groups of up to 40 other Orcas known as pods. A study showed findings that each pod communicates with each other differently, much like different languages. This allows the pod to hunt together efficiently, increasing their chance of predation and feeding. They can do this because their brains are very complex, almost as complex as a human’s brain. A study investigated the complexity of the brain of cetaceans and found “some of the most sophisticated cognitive abilities among all mammals”.
Whilst hunting as a pod, the Killer Whales have many different techniques to hunt their prey. One of the most infamous ways that they capture their prey is by “wave washing“. They do this by charging at unsuspecting prey upon ice floes, creating a large wave which is intended to knock the prey (in this case, a seal) off into the water. Once the seal is in the water, it’s game over.
Orcas have definitive dorsal fins which differ from each individual, this allows marine biologist to easily identify the Orcas to keep notes on their migratory patterns, size and general well being. One study showed that a number of individuals had heavily damaged dorsal fins with some bent and other completely collapsed. It is most likely due to competition between males to determine the alpha male of the pod.
Reproduction between Orcas starts at around 15 years of maturity. The gestation period of the Orca is 16-17 months, giving birth to one calf which will be nursed for one year. It is not uncommon for the mother to return and birth at the mating grounds that she was impregnated in.
Orcas are not yer considered an endangered species, however with many threats to the already small population, from commercial hunting, habitat pollution, climate change, collisions with boats and many others, if they are not protected they could very easily end up on the endangered animals list. Orcas can be considered indicator species, due to being the top predators they are, if the population drops suddenly it can show the health of the marine food web.
One of the most horrific and eye opening pieces of media to alert the general public about Orcas in captivity was the film “Blackfish“. The film exposed the truth behind keeping Killer Whales in tiny enclosures and forcing them to entertain millions of paying customers, grossing profits un-imaginable. This triggered thousands of petitions and groups to end the cruelty of keeping Orcas in captivity. People tend to forget that Killer Whales are deadly apex predators and shouldn’t be used for profit. Fortunately SeaWorld has finally agreed to stop using Orcas for entertainment, and that there will be no more Orca shows or breeding.