A Killer Whale Treble
Last year an exciting discovery of an extinct species of small humans made headlines. Killer whales (Orcinus orca) also have a small relative, the pygmy killer whale (Feresa attenuata), but theirs still survives. Little is known about the species. Until 1952 only two skulls of the small whales, discovered in the 1800s, provided information about them. Even today the portrait of the pygmies is being slowly sketched in from details gleaned from occasional strandings and bycatch. Their numbers in the wild are uncertain, and no one knows how much their social behavior matches that of their larger brethren.
What is known is that the pygmy killer whale is actually a member of the dolphin family, like its larger cousin, resembling a stereotypical dolphin, but without the beak. It is also dolphin-size—at six and a half feet (two meters), about a third as long as an orca.
The pygmy killer whale lacks the loud, distinctive, and familiar black-white-and-gray coloration of the proper killer whale. Rather it has a reserved all-black color, with some white around the lips.
Killer whales are found in every ocean, but exhibit a preference for the cooler waters towards the Poles. But while sharing a global distribution, the pygmies prefer warmer climes of tropical and subtropical waters. Both are highly gregarious; pygmies are seen in groups of up to 50 animals. Killer whales eat fish and marine mammals; likewise pygmy whales eat primarily fish, but have been observed chasing and killing smaller dolphin species in gangs.
Yet another whale-that-is-really-a-dolphin sharing the "killer whale" moniker is the false killer whale (Pseudorca crassidens). Not close to killer whales genetically, the false killer whale has a nearly identical skull shape, hence it was given that name.
The falses are about 18 feet (five meters) long, are all black with a rounded head, inhabit open water, and feed on pelagic fish and squid. Again, much like the pygmy and the orca, they also have a taste for mammals and have been seen hunting sperm whales (Physeter macrocephalus) and the calves of humpbacks (Megaptera novaeangliae). Like the other two killer whales the falses are very social, with groups of up to 800 reported.
Although there is little information about the falses, one tragic aspect of their life is well documented: mass strandings. These unexplained strandings can involve hundreds of individuals.
In terms of genetics, what is the killer whale's closest relative? It is in fact an unlikely candidate that makes its home in the large river systems and coastlines of Southeast Asia, the Irrawaddy dolphin (Orcaella brevirostris).
Picture it. You're a seal, chillin' (literally) on an ice floe in the waters surrounding Antarctica, taking a break on a small floating chunk of ice, away from predators. The next thing you know a killer whale (Orcinus orca) has erupted from the water and landed on your once blissful chunk of ice. The weight of the intruder causes the ice floe to tilt, causing you to slip along the ice and spill into the ocean, dangerously close to the other killer whales waiting in the water.
Killer whales have evolved some amazing behaviors to bypass what would seem to be a boundary for a fully aquatic predator – land (or frozen ice). Some of the best-recorded examples of this come from Antarctica.
As is described in our magazine article, orcas use either active echolocation (sonar) or passive listening to locate, target, and pursue their prey. However those techniques do not work especially well for prey out of the water. Thus some of the crafty orcas in Antarctica spy hop their quarry. That is, they seem to locate hauled-out seals and sea lions by sticking their heads up out of the water (sometimes emerging six feet [two meters] or so) and having a good look around.
Once it has located its prey, an orca employs one of numerous techniques to catch the ill-fated seal. If the seal is on thin ice, no problem, the whale merely crashes through the ice and grabs the seal. Sometimes a group of whales will swim rapidly straight toward the seal, veering dramatically at the last moment to create a wave that washes the hapless prey into the ocean. Unsubstantiated reports claim that a killer whale once even landed onshore, biting and holding a seal. Then two other orcas in the water bit onto the stranded whale's fluke (tail) and dragged it and their dinner back into the water.