Common minke whale this mistake during Foyn's whaling operations in the Varanger Fjord between 1868 and 1885." It has formerly been known as the little piked whale, the lesser or least rorqual, and the sharp-headed finner. American whalemen in the 19th century simply thought of them as "young finbacks" or a "Finback's calf", apparently under the impression that they were juveniles of their larger relative, the fin whale. They were also called zwergwal (German: "dwarf whale") or vågehval (Norwegian: "bay whale"). In Japan they are called koiwashi-kujira ("little sardine whale") or minku-kujira ("minke whale"). In Greenland they are known by the Danish name
Sei whale Norwegian word "røyrkval", meaning "furrow whale", because family members have a series of longitudinal pleats or grooves on the anterior half of their ventral surface. Balaenopterids diverged from the other families of suborder Mysticeti, also called the whalebone whales or great whales, as long ago as the middle Miocene. Little is known about when members of the various families in the Mysticeti, including the Balaenopteridae, diverged from each other. Two subspecies have been identified—the northern sei whale ("B. b. borealis") and southern sei whale ("B. b. schlegelii"). Their ranges do not overlap. The sei whale is the fourth-largest balaenopterid, after