Why do hooded seal pups nurse for only four days?

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A crabeater seal (Lobodon carcinophagus) lies on snow-covered ice with its mouth open, surrounded by broken sea ice in East Antarctica. — seal Crabeater seal (*Lobodon carcinophagus*).

The hooded seal (Cystophora cristata) exhibits one of the shortest lactation periods among mammals, lasting only four days. This rapid nursing phase is highly efficient, allowing the pups to consume approximately 10 litres (2.6 gallons) of milk daily.1

This intense nutritional intake enables the pups to gain weight at a remarkable rate of 7 kg (15 pounds) per day. By the end of this four-day period, the pups have nearly doubled their birth weight, reaching up to 60 kg (130 pounds). Following this brief period of rapid growth, the pups are weaned and enter a fasting stage for several weeks before they begin to hunt independently in the water. This evolutionary strategy allows the young seals to quickly build the necessary blubber reserves to survive the transition to independent feeding.1