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Brain Growth in the Harbor Porpoise and Pacific White-Sided Dolphin

Lori Marino
DOI: http://dx.doi.org/10.2307/1383186 1353-1360 First published online: 6 December 1999


There have been few studies of brain growth in cetaceans despite their potential importance for understanding cetacean, and generally mammalian, brain-behavior relationships. Among terrestrial mammals, and notably primates, high encephalization levels and long juvenile periods of dependency are associated with a prolonged period of brain development. I examined brain-growth patterns in the harbor porpoise (Phocoena phocoena) and Pacific white-sided dolphin (Lagenorhynchus obliquidens). The brain of P. phocoena is substantially more mature throughout development than that of L. obliquidens, and brain-growth patterns are related generally to adult encephalization levels in these two species. Various factors, such as habitat type and body size, are likely to play an interrelated role in brain development in cetaceans.

Key words
  • Pacific white-sided dolphin
  • Lagenorhynchus obliquidens
  • harbor porpoise
  • Phocoena phocoena
  • cetacean
  • brain growth