On 9 September 1972, a Californian surfer, Hans Kretschmer, testified that he was bitten by a killer whale at Point Sur. However, scientists have questioned the anthropophagic motivation of the animals, as the man, wrapped in fur, could have been mistaken for a penguin. Only few wild killer whale attacks on humans have been historically recorded and even less were the reported boat attacks: In an expedition to Antarctica at the beginning of the 20th century, the Terra Nova expedition, the photographer Herbert Ponting, approached a group of orcas and returned to the ship after feeling the ice blocks move under the pressure of the whales› blows, which presumably wanted to knock him into the water. Usually, in the wild, orcas are not afraid of boats and often approach them peacefully, notably orca’s sightseeing tours for tourist are available all over the world. When the pray is a large cetacean, all members of the group participate in the hunting, some holding the animal by the tail while others strike it from all sides. Hunts can take place in the open sea or near the coast, in which case the prey is driven ashore until it can no longer escape its predators. Killer whales use echolocation, a natural sonar system, for social interactions and hunting. For example, in the southern hemisphere, pinnipeds are sometimes hunted by deliberately stranding them on the beach. The range of hunting techniques developed by killer whales is vast, depending on both the prey and the environment. ![]() Killer whales live, move and hunt in groups of 3 to 40 individuals in most oceans (called pods). Females reproduce until they are forty years old, raising an average of five offspring.Īccording to a study financed by SeaWorld, captive orcas have an average life expectancy of 41.6 years (both sexes combined) compared to the 29 years for populations of free killer whales. Newborns are breastfed for two years but begin to feed themselves at twelve months of age. Mothers give birth to a single calf approximately once every five years. The gestation period varies from fifteen to eighteen months. From this age onwards, female individuals have fertile periods spaced three to sixteen months apart. Orcas become adults in about fifteen years. It is shaped like a triangle, whereas the female’s dorsal fin is shorter and falciform.įigure 1: Killer whale sexual dimorphism (male in front and female in the background) (picture from national oceanic and atmospheric administration, Male killer whales measure between 6 and 9.5 meters and weigh between 3.6 and 9 tons females are smaller, measuring between 5.2 and 7.3 meters for a mass of between 1.3 and 3.6 tons. The male’s dorsal fin is larger than the female’s (about 90 cm) and can be 1 to 2 meters high. The body is topped by a large dorsal fin with a dark grey saddle-shaped patch just behind it. They have a characteristic appearance with a black back, white belly and a white patch behind and above the eye. Orcas or killer whales are marine mammals that feed on other marine mammals, fish and birds. ![]() So let’s go back to our Iberian population of orcas causing many problems in the open waters between Gibraltar and the north of Spain. You are a beautiful example for me as a young scientist but also as a person. No orca encounter for us, only a beautiful experience, some dolphins, many interesting people and 400 kilometers from La Coruna to Porto.īefore digging more into the killer whale topic, I really would like to thank Thierry and Barbara for the amazing experience, the trust and the energy they have put every day in what they believe. Actually, when Thierry first told me about this new atypical behavior of some orcas that started attacking boats exactly where we wanted to go, I was a bit worried but also sad as I would have loved to encounter these beautiful animals, but given the situation probably was better so. ![]() Never had I expected that already the first evening, around the dinner table, the topic for my project would be already so clear. When I first encountered Thierry and Barbara on board of their fantastic Gaia, I was amazed by the opportunity that they and SJf gave to me, to spend two weeks on board, experiencing the open sea. Killer whale: Is the nomenclature of this marine mammal more appropriate as we had ever thought? (Probably not)
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |