They’re both enormous. They both live in the ocean. And they both have “whale” in the name. So what exactly is the difference between a whale and a whale shark — and why does it matter?
The confusion is understandable, but the two animals are about as different as ocean creatures can get. Here’s a complete breakdown of what separates them, and why the waters off Southern California are home to one but not the other.
The Most Important Difference: One Is a Mammal, One Is a Fish
The single biggest distinction between whales and whale sharks comes down to biology. Whales are mammals. Whale sharks are fish.
What does that mean in practice? Whales breathe air through lungs — they must surface regularly to breathe through their blowholes, which is what creates the iconic spout you see on a whale watching tour. They are warm-blooded, give birth to live young, and nurse their calves with milk. In every biological sense, whales have more in common with humans than they do with fish.
Whale sharks, on the other hand, are fish — the largest fish species on Earth, in fact. They breathe through gills, are cold-blooded, and reproduce differently from mammals. Despite their immense size, they are sharks, belonging to the same class as great whites and hammerheads.
Size: How Do They Compare?
Both animals are genuinely massive, which is part of why people conflate them. But in terms of sheer size, whales win decisively.
The blue whale is the largest animal ever known to have existed on Earth — reaching lengths of up to 100 feet and weighing as much as 200 tons. Even mid-sized whale species like humpbacks and gray whales are enormous by any standard. You can read more about just how large blue whales get in our post How Big Is a Blue Whale? Size Explained From Skull to Tail.
Whale sharks are the largest fish on Earth, typically reaching 18 to 32 feet in length and weighing up to 20 tons. Impressive — but still significantly smaller than the largest whale species.
Diet: Filter Feeders vs. Active Hunters
Here’s something that surprises many people: despite their size, both whales and whale sharks can be filter feeders — but the similarity mostly ends there.
Whale sharks feed almost exclusively on plankton, small fish, and fish eggs, swimming slowly with their enormous mouths open to filter food from the water. They pose no threat to humans and are known for their gentle, docile nature.
Whales vary considerably in diet depending on species. Baleen whales — including blue whales, humpbacks, and gray whales — are filter feeders like whale sharks, using baleen plates to strain krill and small fish from the water. Toothed whales, including orcas and sperm whales, are active predators that hunt fish, squid, and in the case of orcas, marine mammals. For a closer look at one of the ocean’s most complex predators, see our post on Types of Killer Whales and the New Species.
Where They Live
Whale sharks are found in warm, tropical, and subtropical waters around the world — think the Indo-Pacific, the Gulf of Mexico, and the waters around Australia. They are not a species you’ll encounter off the coast of Southern California.
Whales, on the other hand, are very much a Southern California story. The waters off Long Beach and San Pedro are among the most productive whale watching waters on the Pacific Coast. Gray whales migrate through from December through April. Blue whales feed in these waters from May through November. Humpbacks, fin whales, and minke whales are spotted throughout the year. Check our live whale sightings page to see what’s been spotted recently off the coast.
Lifespan and Intelligence
Whales are among the longest-lived and most cognitively complex animals on Earth. Bowhead whales can live over 200 years. Humpbacks and blue whales regularly live 80 to 90 years. Whales are known for sophisticated communication, social bonds, and behaviors that suggest significant intelligence.
Whale sharks live approximately 70 to 100 years — a long lifespan for a fish, but their cognitive complexity is far more limited compared to cetaceans. They are solitary animals that don’t form the kind of social structures observed in whale populations.
The Bottom Line
Whales and whale sharks share a name and a habitat, but biologically they are entirely different animals separated by hundreds of millions of years of evolution. One is a mammal, one is a fish. One breathes air, one breathes water. One you can see off the coast of Southern California — and one you cannot.
If seeing one of the ocean’s true giants is on your list, the waters off Long Beach and San Pedro offer some of the best whale watching in the world. Harbor Breeze Cruises runs tours year-round with experienced crew and on-board naturalists from the Aquarium of the Pacific.
Ready for an adventure? Check our Latest Sightings Report to see if orcas have been spotted today, or Book Your Trip to join us on the water!
