Brain size area in women, corresponding to spatial versus language specializations. Small studies have attempted to link brain volume with functional measures such as P300 auditory evoked potentials but finding no association. Studies attempting to related sibling differences in IQ to differences in brain volume are hampered by relatively small sample sizes and the noisy nature of such difference scores, yielding weak evidence for cross-trait cross-sib correlations. The largest brain is that of the sperm whale, weighing about , and killer whales, weighing about . An elephant's brain weighs just over and a bottlenose dolphin's . Brain size tends to vary according
Right whale whales have a distinctive wide V-shaped blow, caused by the widely spaced blowholes on the top of the head. The blow rises above the surface. Right whales have between 200 and 300 baleen plates on each side of their mouths. These are narrow and approximately long, and are covered in very thin hairs. The plates enable the whale to filter feed. The penis on a right whale can be up to – the testes, at up to in length, in diameter, and weighing up to 525 kg (1157 lbs), are also by far the largest of any animal on Earth.