The image is of a sperm whale Physeter macrocephalus.
"Sperm whales have the largest brain of any animal (on average 17 pounds (7.8 kg) in mature males)".
These sentient whales have the largest brains that have ever existed on Earth.
"Absolute size is the most general of all brain properties [...], and ranges in mammals from brains of small bats and insectivores (weighing less than 0.1 g) to those of large cetaceans (up to 9000 g)."
Credit: Tim Cole, NMFS (NOAA).