Pre- and Postnatal Ontogeny of Brain Size in Beluga and Bowhead Whales

Brain growth in these cetacean species plateaus early, challenging the assumption that cetacean brains grow throughout life. In bowhead, the brain is significantly smaller than the cranial cavity, and this is not the case in beluga. If this observation can be generalized to all mysticetes and odontocetes, it implies that no single equation can capture the proportional volumes of the brain and cranial cavity across the entire cetacean clade.