Lion’s Mane Jellyfish
Photograph by Paul Nicklen, National Geographic
The world’s largest creatures reside in the ocean, and its depths are home to unusual species whose surprising proportions are unknown on land.
Here, an underwater view captures the billowing tentacles of a lion’s mane jellyfish. The most potent species of jellyfish, the lion’s mane can reach a diameter of 6.6 feet (2 meters) with tentacles topping 49 feet (15 meters).
Photograph by Brian J. Skerry
The largest fish in the sea, the whale shark can reach lengths of 40 feet (12 meters) or more. The gentle giants are filter feeders, swimming with their wide mouths open to collect plankton and small fish.
Giant-Spined Sea Stars
Photograph by Chuck Davis, Riser/Getty Images
Rows of large spines cover giant-spined sea stars off the coast of California. Sea stars (also known as starfish) can regenerate limbs, and in some cases, entire bodies.
Giant Spider Crab
Photograph by Emory Kristof
A giant spider crab is illuminated by the lights of a submersible. Protected from some predators by its hard exoskeleton, the creature—which can grow to ten feet (three meters) wide—can also blend in with the ocean floor. Under deeper cover, it can disappear beneath the sponges and other marine life it uses to adorn its shell.
Photograph by Flip Nicklin
Even as a baby, a blue whale can make a grown man look like a minnow. The largest creature ever to live, the blue whale averages 25 feet (7.6 meters) long at birth and weighs about three tons. As an adult, it can easily stretch to the length of a city bus and weigh close to 200 tons.
Photograph by Jennifer Kiewit, Your Shot
Often mistaken for a jellyfish, the Portuguese man-of-war is actually made up of a colony of organisms working together. Its tentacles can extend 165 feet (50 meters) below the surface, although 30 feet (10 meters) is more the average.
Photograph by Daisy Gilardini/Getty Images
The fin whale is the second largest creature on Earth, reaching maximum lengths of 82 feet (25 meters) for males and 89 feet (27 meters) for females. Fins are baleen whales: They use the fringelike baleen in their mouths to strain krill and tiny fish from the massive amounts of water they ingest as they feed.
Photograph by David Schrichte/Seapics.com
Related to shrimp and crabs, the giant isopod is a deep-sea crustacean that makes its home on the ocean floor. It is the largest of the known isopods, which on land includes the relatively tiny pill bug.
Great White Shark
Photograph by Mauricio Handler
A great white shark swims in the clear waters off Guadalupe Island. The largest predatory fish on Earth, great whites grow to an average of 15 feet (4.6 meters) in length, though larger specimens have been recorded. They prey mainly on sea lions, seals, and small toothed whales.
Photograph by Sami Sarkis/Getty Images
The largest mollusks on Earth, adult giant clams permanently affix themselves to surfaces such as sand or coral reef rubble. The behemoths are capable of reaching 4 feet (1.2 meters) long and weighing more than 500 pounds (227 kilograms). They can live a hundred years or more in the wild.
Giant Clam Siphon
Photograph by Mike French, My Shot
A giant clam’s siphon is used to draw in water to filter and consume passing plankton. Though South Pacific legends describe clams that lie in wait to trap unsuspecting swimmers or swallow them whole, no account of a human death by giant clam has ever been substantiated.
- Ballard, Robert
- Bowermaster, Jon
- De Rothschild, David
- Doubilet, David
- Earle, Sylvia
- Frozen Seafood Benefits
- Goodman, Beverly
- Habitat Destruction
- Invasive Species
- Kristof, Emory
- Marine Food Chain
- Marine Pollution
- Nicklen, Paul
- Norman, Brad
- Ocean Overview
- Pristine Seas Expeditions
- Sala, Enric
- Seafood Decision Guide
- Seafood Substitutions
- Sea Level Rise
- Sea Temperature Rise
- Seaver, Barton
- Sustainable Seafood
- Thys, Tierney
- Tips to Save the Ocean
From the Channel
Support the Ocean
Help protect the last healthy, undisturbed places in the ocean so we can learn how to help healthy reefs thrive, help unhealthy reefs recover, and better preserve the ocean.
Explore the Ocean
Order ocean books, DVDs, maps, and more from the National Geographic online store.
Explore the world's oceans, from their prehistoric beginnings to modern-day efforts to preserve their natural wonder.
Immerse yourself in the wonders of the deep through colorful maps, photos, and satellite images.
Engage, Conserve, Restore
The National Geographic Society’s freshwater initiative is a multi-year global effort to inspire and empower individuals and communities to conserve freshwater and preserve the extraordinary diversity of life that rivers, lakes, and wetlands sustain.