Whales in the Galapagos Islands
Minke Whale |
Bryde's Whale |
Sei Whale |
Humpback Whale |
Fin Whale |
Blue Whale |
Sperm Whale |
Short Finned Pilot Whale |
The Orca or Killer Whale (Orcinus orca) is also less commonly known as 'Blackfish' or 'Seawolf'. It is the largest species of the oceanic dolphin family (Delphinidae). It is found in all the worlds oceans, from the very cold Arctic and Antarctic regions to warm, tropical seas to the tropical cold seas of the Galapagos Islands.
Orcas come to the Galapagos archipelago in hunting rides and often you will find them near by places where there are sea lions. Orcas have been seen hunting dolphins and even Bryde’s whales. Orcas travel in familiar groups or pods, where a dominant male is the leader of the pod, accompany by two to four females and a young Orca or two.
Orcas are versatile and opportunistic predators. Some populations feed mainly on fish, others hunt marine mammals, including sea lions, seals and even large whales. There are up to five distinct Orca types, some of which may be separate subspecies or even species.
Orcas are highly social. Some populations are composed of matrilineal family groups (a system in which one belongs to ones mother's lineage) which are the most stable of any animal species. The sophisticated social behaviour, hunting techniques and vocal behaviour of Orcas have been described as manifestations of culture.
Although Orcas are not an endangered species, some local populations are considered threatened or endangered due to pollution, depletion of prey species, conflicts with fishing activities and vessels, habitat loss and whaling. Wild Orcas are usually not considered a threat to humans. There have, however, been isolated reports of captive Orcas attacking their handlers at marine theme parks.
The Orca is suggested to be one of the oldest dolphin species, However, it is unlikely to be be as old as the family (Delphinidae) itself, which is believed to date back at least five million years.
The name 'Orca' (plural 'Orcas') was originally given to these animals by the ancient Romans. The term 'orc' has been used to describe a large fish, whale or sea-monster. It is now considered an obsolete equivalent for 'Orca'.
The name 'killer whale' is widely used in common English. However, since the 1960s, 'Orca' has steadily grown in popularity as the common name to identify this species and both names are now used. The species is called Orca in most other European languages.
Orcas are sometimes referred to as blackfish, a group including pilot whales, pygmy and false killer whales and melon-headed whales. A former name for the species is grampus. This is now seldom used and should not be confused with the Grampus genus, whose only member is Risso's Dolphin.
Orcas are distinctively marked, with a black back, white chest and sides and a white patch above and behind the eye. Orcas calves are born with a yellowish or orange tint, which fades to white. Orcas have a heavy and stocky body and a large dorsal fin with a dark grey 'saddle patch' at the fins rear. Male Orcas can range from 6 - 8 metres long (19 - 26 feet) and weigh in excess of 6 tonnes; it has been reported that especially large males have reached nearer 8 tonnes. Female Orcas are smaller, growing from 5 - 7 metres (16 - 23 feet) and a weight of about 5 tonnes. The largest Orca ever recorded was a male off the coast of Japan, measuring 9.8 metres (32 feet) and weighed over 8 tonnes. Calves at birth weigh about 180 kilograms and are about 2.4 metres long (8 feet). The Orcas large size and strength make them the fastest marine mammals, often reaching speeds in excess of 56 km/h (35 miles per hour).
Unlike most dolphins, the pectoral fin of an Orca is large and rounded and used more of as a paddle than in other dolphin species. Males have significantly larger pectoral fins than females. At about 1.8 metres (6 feet), the dorsal fin of the male is more than twice the size of the females and it is more of a triangle shape, a tall, elongated isosceles triangle, whereas the dorsal fin of the female is shorter and generally more curved.
Adult male Orcas are very distinctive and are unlikely to be confused with any other sea creature. When seen from a distance in temperate waters, adult females and juveniles can be confused with various other species, such as the False Killer Whale or Risso's Dolphin.
Orca Whale Reproduction
Female Orcas become mature at around 15 years of age. They then have periods of polyestrous cycling (recurring physiologic changes that are induced by reproductive hormones) with non-cycling periods of between three and sixteen months. The gestation period varies from fifteen to eighteen months. Females give birth to a single offspring about once every five years. Births occur at any time of year, with the most popular months being those in winter. Calves nurse for up to two years, but will start to take solid food at about twelve months. All resident Orca pod members, including males of all ages, participate in the care of young whales.
Cows (female orcas) breed until the age of 40, meaning that on average they raise a total of five offspring throughout their lives. Typically, females live to the age of fifty, but may survive well into their eighties or nineties in exceptional cases. Males become sexually mature at the age of 15, but do not typically reproduce until age 21. Males live to about 45 on average and up to 90 in exceptional cases. The lifespans of captive Orcas are significantly shorter, usually less than 25 years.
Orca Whale Distribution
Orcas are found in all oceans and most seas, including (unusually for cetaceans) the Mediterranean and Arabian seas. However, they prefer cooler temperate and polar regions. Although sometimes spotted in deep water, coastal areas are generally preferred to pelagic environments.
Orca Whale Behaviour
Orcas can survive in most water temperatures. Sightings are rare in Indonesian and Philippine waters. No estimate for the total worldwide population exists. Local estimates include 70,000 – 80,000 in the Antarctic, 8,000 in the tropical Pacific (although tropical waters are not the Orca's preferred environment, the sheer size of this area, 19 million square kilometres, means there are thousands of Orcas), up to 2,000 off Japan, 1,500 off the cooler north-east Pacific and 1,500 off Norway. Adding very rough estimates for unsurveyed areas, the total population could be around 100,000.
The migration patterns of Orcas are poorly understood. Each summer, the same resident Orcas appear off the coasts of British Columbia and Washington State. After decades of research, it is still unknown where these animals go for the rest of the year.
Orcas often raise their bodies out of the water in a behaviour called spy hopping. The day-to-day behaviour of Orcas is generally divided into four activities: foraging, travelling, resting and socializing. Orcas are generally enthusiastic in their socializing, engaging in behaviours such as breaching, spy hopping and tail-slapping.
Orcas can also be seen swimming with porpoises, other dolphins, seals, and sea lions, which are sometimes common prey. Orcas are continually on the move, sometimes travelling as much as 160 km (100 miles) in a day, but may be seen in a general area for a month or more. Range forOrca pods may be as much as 1300km (800 miles) or as little as 320km (200 miles).
Orcas commonly breach, often lifting their entire body out of the water.
Orca The Apex Predator
The Orca is an apex predator (predators that, as adults, are not normally preyed upon in the wild). They are sometimes called the 'wolves of the sea' because they hunt in packs like wolves. On average, an Orca eats 227 kilograms (500 pounds) of food each day.
Orcas prey on a diverse array of species. However, specific populations show a high degree of specialization on particular prey species. For example, some populations in the Norwegian and Greenland sea specialise in herring and follow that fishes migratory path to the Norwegian coast each autumn. Other populations in the area prey on seals. In field observations of the resident whales of the northeast Pacific, salmon accounted for 96% of animals' diet, with 65% of the salmon being the large, fatty Chinook. They have been observed to swim through schools of the smaller salmon species without attacking any of them.
Although resident Orcas have never been observed to eat other marine mammals, they are known to occasionally harass and kill porpoises and seals for no apparent reason.
Fish-eating Orcas prey on 30 species of fish, particularly salmon (including Chinook and Coho), herring, and tuna, as well as basking sharks, oceanic whitetip sharks and smooth hammerheads. In New Zealand killer whales have been observed hunting stingrays as well. Cephalopods, such as octopuses and a wide range of squids and reptiles, such as sea turtles, are also targets.
Groups of Orcas attack even larger cetaceans such as Minke Whales, Grey Whales, and very occasionally Sperm Whales or Blue Whales. Orcas generally choose to attack whales which are young or weak. However, a group of five or more Orcas may attack healthy adult whales. Bull Sperm Whales are avoided, as they are large, powerful and aggressive enough to kill orcas.
When hunting a young whale, a group of Orcas chases it and its mother until they are both worn out. Eventually the Orcas manage to separate the pair and surround the young whale, preventing it from returning to the surface to breathe. Whales are typically drowned in this manner. Pods of female Sperm Whales can sometimes protect themselves against a group of Orcas by forming a protective circle around their calves with their flukes facing outwards. This formation allows them to use their powerful flukes to repel the Orcas. Hunting large whales, however takes a lot of time, usually several hours. Orca cannibalism has also been reported.
Other marine mammals prey species include most species of seal and sea lion. Walruses and Sea otters are taken less frequently and Polar bears are rarely taken.
Fish-eating Orcas in the North Pacific have a complex but extremely stable system of social grouping. Unlike any other mammal species whose social structure is known, Resident Orcas of both genders live with their mothers for their entire lives. Therefore, Orca societies are based around matrilines consisting of a single female (the matriarch) and her descendants. The sons and daughters of the matriarch form part of the line, as do the sons and daughters of those daughters. The average size of a matriline is nine animals.
Because females can live for up to ninety years, it is not uncommon for four or even five generations to travel together. These groups are highly stable. Individuals split off from their matrilineal group only for up to a few hours at a time, in order to mate or forage. No permanent casting-out of an individual from a matriline has ever been recorded.
Like other dolphins, Orcas are highly vocal. They produce a variety of clicks and whistles used for communication and echolocation. The vocalization types vary with activity. While resting they are much quieter, emitting an occasional call that is distinct from those used when engaging in more active behaviour.
Orca mothers have been observed training their young in the pods dialect. The mother uses a simplified version of the pods dialect, a sort of baby-talk, when training a calf. This suggests that Orca vocalization has a learned basis in addition to an instinctual one.
Orcas are well known for their mental capabilities. Studies have indicated that an Orca has an outstanding memory.
Environmental degradation, depletion of prey species, conflicts with fishing activities and habitat loss are currently the most significant threats to Orcas worldwide.
Stocks of most species of salmon, a main food source for resident Orcas in the northeast Pacific, have declined dramatically in recent years. On the west coast of Alaska and the Aleutian Islands, populations of seals and sea lions have also undergone a major decline. If food is scarce, Orcas must draw from their blubber for energy, which further magnifies the effects of pollutants. In 2005, the United States government listed the Southern Resident community of Orcas as an endangered population under the Endangered Species Act.
Noise from shipping, drilling and other human activities can interfere with the acoustic communication and echolocation of Orcas. In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Orcas subsequently avoided the surrounding waters. In addition high intensity navy sonar has become a new source of distress for Orcas. Orcas are popular with whale watchers, which may change Orca behaviour and stress Orcas, particularly if boats approach Orcas too closely or block their line of travel.
Orcas and Humans
There are few confirmed attacks on humans by wild Orcas. Two such recorded instances include a boy charged while swimming in Alaska, and Orcas trying to tip ice floes on which the photographer of the Terra Nova Expedition was standing.
Much more common than wild Orcas attacking people are captive Orcas attacking people, either their handlers or intruders. ABC News has reported that Orcas have attacked nearly two dozen people since the 1970s.
The name 'Killer Whale' could be presumed an unfair name, the orcas have a bad reputation, yet it is not as bad as human reputation. Orcas kill for survival and to survive, yet humans kill for sport or gain from substances found in whales.
Orcas are very curious whales and if you are swimming or snorkeling, do not miss the chance to see them or even to take a picture of them, just keep a prudential distance for not disturbing them in whatever they are doing. Of course is not recommended to go in the water if they are eating. When people are in the water they could approach to check and keep going. Youngsters are more curious than adults.
Minke Whale |
Bryde's Whale |
Sei Whale |
Humpback Whale |
Fin Whale |
Blue Whale |
Sperm Whale |
Short Finned Pilot Whale |