What is in a name?
There is a whole group of dolphins whose common name actually includes the term “whale”. Not only that, together they are referred to as “Blackfish”. Why is that? How did that happen? The group includes the following species of oceanic dolphins: Killer whale (or Orca), False killer whale, Pygmy killer whale, Melon-headed whale and Long- and Short-finned Pilot whale.
The term blackfish originated at least twice for members of this group of species. It was initially given to the killer whale by the Tlingit and Haida tribes of western Canada. In the 1600’s pilot whales were called “blackfish” by the fishermen in the American colonies, who hunted them in a drive fishery, where the whales were driven towards shore with small boats, much like what is still going on in the Faroe islands.
This was all before animals were divided into various groups based on scientific criteria, so these animals swimming in the ocean were referred to as fish. How the other species of dolphins came to be included among the “blackfish” is not completely clear, but it probably had to do with the challenge of identifying these species in the field, or even when stranded or in the form of a skull.
All of these species are mostly black or dark gray. The killer whale has the most white on its body, with large white areas on its sides and ventral (stomach) area. For the other species the white markings are mostly seen on the ventral area and, for the smallest species, around the lips.
This coloration may partially be explained by the hunting practices of these species. All species but the orca appear to be active and feeding mostly at night on prey like squid and fish that ascend towards the surface after sunset. However, some of the species also feed on other prey at times, which may cause them to change their wake/rest cycle and be more active at other times of the day.
The pilot whales are squid specialists, and therefore are more consistently nocturnal, generally waking up around 4 or 5 in the afternoon. False killer whales and Pygmy killer whales have also been observed to catch very large fish, like mahi-mahi, wahoo and tuna, during the day. False killer whales then feed cooperatively on it - one whale holding the prey while others tear off chunks to swallow. There is even footage of false killer whales sharing their prey with divers. That this has not been described for Pygmy killer whales may be due to the limited amount of observations that have been made on this species.