Mysticeti Baleen Whales

The baleen whales (suborder Mysticeti) are filter-feeders that reach gargantuan size. At 100,000 kg or more, a fully-

grown blue whale attains the largest mass of any animal. This large mass allows females to mobilize vast quantities of nutrients from body reserves during lactation.[4,9] Most of the very large species, such as gray, humpback, fin, and blue whales, migrate back and forth between high-latitude/polar regions, where they feed, and warm temperate/tropical regions, where they give birth and lactate but fast or feed little.[4] In blue and fin whales, the calves gain about 50 80 kg/d, ingest milk containing 32 35% fat, and are weaned at 6 7 months (Table 1). This short lactation, relative to body size, minimizes the time spent on breeding grounds where food resources are sparse. The amounts of milk (220 kg/d) and milk-energy (4000 MJ/d) that blue whales are estimated to produce far surpass those of other mammals, but in relation to maternal metabolic size, the daily output of milk-energy (0.72 MJ/kg075/d) is not remarkable, resembling that of many terrestrial mammals.

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Pregnancy And Childbirth

Pregnancy And Childbirth

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