This month's column in The Cambrian:
The seals look like something terrible is happening to them.
Their skin is peeling off! Talk about splotchy skin. But for northern
elephant seals, it’s the normal, annual molt.
seals, like only one other seal (the Hawaiian monk seal) molt their
skin annually in a few short weeks. All other seals molt, but most do so
gradually, so it isn’t as noticeable.
A new skin layer forms
beneath the old skin. Blood supply to the old skin ceases and the old
skin peels off in pieces. Scraps of it skitter across the beach. Friends
of the Elephant Seals docents have samples of it to show visitors.
Children enjoy handling it. Adults seem to be more dubious, extending a
cautious finger for a touch.
The seals stop eating when they are on the beach at the
rookery, fasting for that four to six weeks it takes for them to
complete their molt.
Females gain weight
the females were last on the beach, at the end of lactation in
February, they were thin. They’d converted their blubber to milk to
nourish their pups. They’ve spent the past two months eating and gaining
The mother-to-be spent the
next two months or so feeding freely in her ocean home. When she returns
to the beach in April to molt, her body makes the changes needed to
have a pup next season.
After she’s finished molting and returns
to the ocean, that embryo implants in the uterine wall and begins normal
development. Delaying development of the embryo gives her time to gain
weight before starting the demands of the next pregnancy.
Staying at sea
is 7.5 months. When they leave the beach after molting, the expectant
mothers will remain at sea until they return to give birth next
Delayed implantation is part of a complicated life
cycle. Spending most of the year solitary in the water requires
different strategies for breeding. So far as their lives are understood,
males and females don’t encounter each other except on the beach during
breeding season. This is how the species has worked it out.
2015 breeding season produced about 4,900 live young-of-the-year, a 9
percent increase over 2014. Fewer females and fewer pups were actually
born, but more survived, thanks to the mild winter weather.