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Orcas - these beautiful creatures are commonly known as "killer whales." However they belong to the dolphin family. They are the largest of all dolphins, are found in all of the Seas, and are one of the most widely distributed animal species on earth. As the top predator of the sea, their diet consists of hundreds of species - much more diverse than any other mammal. They even consume their close relatives - dolphins! They eat fish, turtles, stingrays, seals, sea lions, squid, birds, "baby" humpback whales, and even (as personally observed by a friend of mine) an occasional moose! Interestingly, there has never been a recorded instance of an Orca attacking a human.
The teeth of the Orca interlock top and bottom and fit tightly together when they chomp their prey. Once they have a mouthful they either swallow the whole chunk, or if small their entire prey. They consume about 130 pounds (about 50 kilos) a day, so hence are almost continuously on the hunt for food. Although researchers have found some 22 different types of mammals in the stomachs of transient Orcas, different groups tend to "specialize." For example, transient groups that regularly transit local waters around Juneau "specialize" in Sea Lions.
"Resident" Orcas do not feed on mammals at all, but have preferences within the fish family. For example, resident Orcas of Alaska prefer Silver and King Salmon over Pink Salmon.
Orcas work as a team, and are often referred to as the "wolves of the sea." They communicate effectively with one another, but are typically totally silent when on the hunt, becoming very "chatty" once prey has been located. They will stun their prey by leaping upon them and swatting or flinging them in the air with their flukes. On one occasion a full grown Stellar Sea Lion of about 600 to 800 pounds (about 250 - 350 kilos) was about a boat length from me when a huge Orca leapt from the water atop him. Some seconds later the Sea Lion was thrown like a rag doll about 15 - 20 feet (5 - 6 meters) in the air! They have been seen going on rocks and beaches to snatch seals and sea lions. A researcher in Alaska in a 15 foot Boston Whaler had a harbor seal jump aboard, and stay there as the Orcas called loudly, "spy-hopped," and circled the boat for some time before giving up and leaving.
The adult male Orca is distinguished by a tall (6 foot; 2 meters) dorsal fin that is very pointed at the top. (Note the smaller dorsal fins on the three Orcas to the right of the male. The first is of a "baby," and the other two are either juveniles and/or females.)
Orcas are about 7 - 8 feet (2.5 m) and about 350 pounds (160 kg) at birth. Adults typically range between about 23 to 33 feet (10 m) and 4 tons (female) to 7 tons (male) pounds (3,500 - 5,600 kg) Males mature between 12 - 14 years, and females about 10 - 15 years. Females live about 50 - 60 years, while males live about half that long. In the Northern hemisphere they mate from July through September. Gestation periods are estimated between about 12 - 16 months, with births between October and March. The female gives birth to one calf at a time, and will bear a total of about 3 - 10 calves during her lifetime. Orcas nurse their young for about 16 months.
Though not an endangered species, they are protected by Federal Law.There are some 1500 Orcas (both resident and transient) in Alaska.
Although Orcas can stay undewater for as long as twenty minutes, and dive as deep as 800 feet (250 m), typically they dive for about five to ten minutes. Their exhalation "blows" are bushy in appearance and about 10 feet in height.
Transient pods of sizes up to 6-7 Orcas often travel through Juneau area waters.
