Fasting by Species

The various groups of marine mammals share many similar behaviors and life history traits. Despite these similarities, they have often evolved for very different reasons. For example, numerous species fast for certain periods each year, but often with very different motivations for doing so. Discuss the motivation for fasting (or not) in the species listed below. Which species do not fast and why? For those that do fast: When do they fast and for how long? Also, why do they fast? Which sex fasts? For each species, what is the benefit gained by not eating during the fasting period? Or, why is it not worthwhile to feed? Or, why are they unable to feed?

Polar Bear

Females fast during nursing in the winter

Otariid

Temporal and spatial predicability - females clustered in best habitat for short period

Males arrive to habitat early to establish and defend territory, males fast in order to control territory throughout the mating period for best success.

Pack Ice Seal

Lactation occurs fast, and non-stop - females fast during lactation

Fast Ice Seal

Lactation occurs fast, and non-stop - females fast during lactation

Humpback Whale

Long migrations to mating grounds which are low in food - they may eat occasionally during migration, but mostly fast until return to feeding grounds

Lactation also occurs during migration - fasting

Elephant Seal

Temporal and spatial predicability - females clustered for short period

Males fast in order to defend and control harem for mating period

Bottlenose Dolphin

Mobile, promiscuous groups - no need for fasting

Sea Otter

Broad mating periods near shore, abundant prey - no need for fasting

Manatee

mating herds in shallows, no migration - no need for fasting (available food)