Page "Killer whale" Paragraph 23

Types B and C live close to the ice pack, and diatoms in these waters may be responsible for the yellowish coloring of both types.

Mitochondrial DNA sequences support the theory that these are recently diverged separate species.

More recently, complete mitochondrial sequencing indicates the two Antarctic groups that eat seals and fish should be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data.