"Everyone who climbed back aboard after such an encounter was breathless from exertion, but more so from excitement," Pack said. "Often, we could see their large eye rotating in its socket watching us, benignly it seemed, as they glided slowly by," he added. "As you can imagine, it's sometimes 'heart-stopping' being in the midst of these huge leviathans, the males charging at each other with great acceleration, the lone female untouched, yet appearing to take in all the action and likely assessing the fitness of her potential suitors." Fitness appears to be behind the whales' fondness for fat and long bodies, since the researchers also discovered that the largest females also produced the biggest calves. Since whales depend upon stored body fat to support their metabolic requirements, particularly during the winter, the extra heft is necessary for their survival, promoting greater reproductive success and aiding females in the nursing of their offspring. Big may also be valued in killer whale pods. Another new study, led by Eric Ward from the Northwest Fisheries Science Center, found that killer whale females nearing menopause -- which tend to be larger since they're fully grown adults -- make the best mothers. "Older females may be more successful in raising young because of maternal experience, or they may allocate more effort to their offspring relative to younger females," Ward explained. Proving that there is life over 50, at least among giant marine mammals, female killer whales can live to be more than 90 years old, long after their courting and calf-rearing days are over. Related Links: Jennifer Viegas' Blog: Born Animal Science Channel: Valentine's Day Quiz |
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