What can an elephant seal – a 4,000 pound, bellowing monstrosity that looks like a melted Yankee Candle – teach us about the world?
Plenty, it turns out.
“The animals are amazing. I mean, everything they do is extreme,” says Daniel Costa, professor of ecology and evolutionary biology at UC Santa Cruz. “They’re the deepest-diving pinniped and they dive for longer than any other seal or sea lion. They also fast for longer. Everything they do is just pushing the limits.”
In the Bay Area, one of the best places to observe elephant seals is Año Nuevo State Park in San Mateo County. The first stop is usually the visitor center, which used to be a creamery, and is filled with fun seal facts like “northern elephant seals spend up to 10 months of the year at sea” and that their favorite foods include “opalescent squid and Pacific hagfish.”
A trail leads for more than a mile over boardwalk and drifting sand, past a gray cliff jutting into the ocean like a slumped-over seal, before arriving at shoreline viewing areas. Here, depending on the time of year, visitors will encounter a sleepy handful or a rowdy convention of elephant seals.
In the fall and early winter, there might be 20 creatures lounging there, occasionally galumphing or issuing a burp noise that echoes over the water. But during the breeding season – which this year runs from December 15-March 31 and requires reservations to attend – it’s a whole different story.
“February is my favorite time to visit. That’s when the big alphas are here,” one of the park’s red-clad docents recently told tourists. “You see births, you see fighting, you see harems — it’s crazy. On the path here, you might see an elephant seal charging toward you like it’s ‘National Geographic.’” (Not intentionally, she clarifies. It’s just that when they get so worked up, they buffalo around with little regard to smaller things in their way.)
Whatever the time of year, it’s quite the experience to meet an elephant seal.
“The males and females are called dimorphic, meaning they have incredibly different body sizes. Males can get up to 5,000 pounds and females are 1,200-1,500 pounds,” says Susan Blake, an interpreter at Año Nuevo State Park. “They look the same until they’re about 3 years old, then the males start growing that big nose and start growing really big. They have a chest shield, a thickened layer of skin that helps them during fights and gets scarred. The big nose is thought to be a male-to-male signal of strength and age.”
That these seals can live to healthy old age is remarkable. Humans once hunted them rapaciously for their sweet, sweet oil.
“The whaling ships would come over and hunt whales, and then they would also leave a group of people on the shore to kill the seals and render their blubber,” says Costa. “They sort of used that to top off their trip, and by (the late 1800s) elephant seals were thought to be extinct.”
In 1892, a research team stumbled across a tiny colony – literally just a dozen elephant seals – on Guadalupe Island off the coast of Mexico’s Baja California. “Back then, if you saw an animal you thought was extinct you needed to put it in the museum,” Costa says. “So they shot all 12 of them. Then they lost several loading them onto the ship. A note from the expedition said something like: ‘It was sad for the elephant seal. But the thirst of science must be quenched.’”
A few must have survived, because the species made a comeback. Soon Mexico laid down a ban on hunting them. In the 1970s, they were sheltered in the United States by the Marine Mammal Protection Act. Today there are thought to be 250,000 northern elephant seals, with about 2,000 in Año Nuevo alone, and other breeding grounds in Point Reyes, Humboldt County and Vancouver Island.
They definitely make their presence known; the universe has gifted these biological equivalents of Stonehenge blocks the ability to tremendously roar. “Males have that big bellow. If you haven’t heard that threat call, it’s ‘buh-buh-buh-buh-boom,’” says Blake. “Every male above a certain age has a unique call; it’s like their name. Sometimes they slam their chest down, and that can actually travel some ways and that will show their size. If need be, then a fight starts — sometimes it just takes a bite or two toward the neck region (to end it).”
When the physical romance happens, it’s not like a Hallmark movie.
“Males have an internal penis. You don’t want things floating around underwater, right? Their penis is pretty large, so everything is streamlined,” says Blake. “They mount a female, and she sometimes makes sounds, sometimes not. It can be hard to tell if the mating was successful. Usually how we know a birth happened is because hundreds of seagulls swoop down to pick at the afterbirth – and then you see a little wriggling, black, slimy pup.”
The pups have the epicurean delight of suckling one of the highest fat-content milks in the animal kingdom. That is, if they can locate their mother’s “inverted nipples,” says Blake. “We’re sometimes out there saying, ‘Go left, go left! A little higher!’”
The young ones swell from 70 to 300 pounds almost a month later. Some have the good fortune to feed from two moms at once, granting them a massive growth spurt and the nickname “super weaners” or – and this is a real technical term – “double mother suckers.”
At some point they undergo something called an “explosive molt.” “All their skin and hair comes off,” says Costa. “It looks like there’s something wrong with them.” Because elephant-seal facts always come in fun multiples, this molting results in a strange phenomenon where the shoreline becomes contaminated with mercury. That’s the result of the creatures’ deep-sea diet of heavy metal-eating tuna and swordfish.
An elephant seal’s life is a constant cycle of hunting, breeding and traveling. Electronic tracking shows that it’s not uncommon for females to swim to the International Date Line, then turn around and come back. While they’re often on the move, they themselves have to move quickly to avoid being eaten by orcas and sharks.
“Off of Año Nuevo, we have a white-shark hot spot. They come in usually around November and December when the huge male and pregnant female seals are coming in,” says Blake. Researchers at Stanford University maintain a buoy that pings when tagged sharks are in the area, and during feeding season it’s “just going off constantly.”
Seals have done much to advance marine science and oceanography. Costa is part of an international Elephant Seal Research program that’s existed in one form or another for six decades; he jokingly refers to the animals as research assistants. There’s ongoing investigations into how seal defecation provides valuable nutrients to the lower layers of the ocean. And it’s thought that elephant-seal carcasses – a massive buffet by anyone’s standards – might act like “whale falls,” in death, feeding creatures at the bottom of the abyss.
“The ocean is very sparsely sampled because it’s expensive and difficult to do. It’s very inexpensive for us to put sensors on elephant seals,” says Costa. “We have one that measures chlorophyll content. And if you remember the ‘warm blob’ that happened some years ago in the Pacific, we were able to define the structure of that blob because elephant seals were measuring the blob down to depth.”
One seal that was part of a study even taught Costa a valuable lesson in bite force.
“I had a female that was slightly drugged and coming out of it, and she latched on to my arm,” he recalls. “Fortunately I had a really thick wool jacket on. But it was a little intimidating to have this female head on my arm, and it left a big contusion that took a month to heal.”
Love bites aside, Costa believes it’s good these seals are doing what they’re doing.
“I like to talk about elephant seals as a success story,” he says. “There’s so much gloom and doom today, but these animals came from less than 25 individuals 120 years ago to expand in population and continue to move north … We didn’t do any innovation other than just say, ‘Hands off, let’s just let them do their thing.’ I think in that, there’s a story.”
IF YOU GO:
For details on 2025-2026’s seasonal elephant-seal experiences, including mandatory reservations, hiking details and black-out periods, visit Año Nuevo State Park’s website at parks.ca.gov/?page_id=523