Evolution

Evolution is occurring slowly and constantly. All life evolved from the sea millions of years ago and ocean species have made adaptations over time to life underwater.

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Sirenians , or seacows, are a group of marine mammals that include manatees and dugongs . Currently, only a single species of seacow is found anywhere in the world. However, the fossil record of...
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This summer, many of you have likely enjoyed feasting on crabs, be they blue,...
Great White Sharks are stealthy hunters and the secret is in their skin. Shark...
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Bioluminescence is one of the more captivating adaptations that have evolved in...

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These "elevator" rudists, an ancient bivalve, used one long heavy valve to anchor themselves in the sediment. They used their tentacles (shown here in pink) to filter food from the sea water. And many often grew together to form...
Today, filter feeders like clams, sponges, krill, baleen whales, fishes, and...
For a long time, scientists thought that some small tentacled fossils were...

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Whales swim, but their ancestors walked. Whales are mammals (like us) whose ancestors lived on land. Life probably began in...
The whales that we see in today's world can broadly be split into two groups: those with teeth (odontocetes), and those that have baleen (mysticetes) instead of teeth. These two groups share a common...
Today, filter feeders like clams, sponges, krill, baleen whales, fishes, and many others fill the ocean, spending their days filtering and eating tiny particles from the water. But when did the first...
This family tree shows how the ancestors of whales moved gradually from land to sea. Early whales took advantage of abundant marine resources, feeding on the ocean's fish, squid and other larger food...
This transparent cockatoo squid ( Leachia sp.), also known as a glass squid, lives in the depths of the ocean and has many adaptations to help it survive there. It retains ammonia solutions inside...
Scientists at the Smithsonian and partnering organizations have discovered a remarkably primitive eel in a fringing reef off the coast of the Republic of Palau . This fish exhibits many primitive...
When you're standing in a museum surrounded by fossils, you can almost imagine drifting through time to when long-extinct creatures swam the ocean. Found all over the world, these fossils can be read...
Great White Sharks are stealthy hunters and the secret is in their skin. Shark skin is covered by tiny flat V-shaped scales, called dermal denticles, that are more like teeth than fish scales. These...
For the last 150 years, paleontologists have debated the origins of the great white shark . Many believe that they descended from the 50-foot megalodon, also known as the megatooth shark (...
Sirenians , or seacows, are a group of marine mammals that include manatees and dugongs . Currently, only a single species of seacow is found anywhere in the world. However, the fossil record of...
Several species of amphipod like this one, Gammarus wilkitzkii , live permanently within Arctic sea ice . These animals are endemic, meaning they only live here. They acclimate to a wide range of...
Invasive species are often in the news these days, with human-transported organisms popping up in unexpected places. But in this era of climate change, there is a whole new kind of invasive species,...
In honor of Mother's Day, the Citizens of the Sea blog salutes ocean-going mothers everywhere. Especially a 60 year-old albatross named Wisdom. She holds the seabird records for both oldest bird and...
This summer, many of you have likely enjoyed feasting on crabs, be they blue, stone, or Dungeness, and a special treat will have been the big, easy morsels of claw meat. The size of this muscle is...
This early whale was well suited to life at sea. But it also may have spent time on land. An ancestor of the right whale , Maiacetus lived 49-40 million years ago. It had flipper-like limbs and...
The basic body plans of all modern animals were set during the Cambrian Period, 542 - 488 million years ago. Your friends, family, and pet turtle may not look much like the creatures here. But we and...
“It is strange to think of a sea turtle as an ecosystem,” says Amanda Feuerstein, program coordinator and research assistant at the Smithsonian’s National Museum of Natural History, “but they are…...
Come one, come all! See the amazing, the astonishing, half-animal, half-plant! Journey to Tampa Bay, Florida, where scientist Skip Pierce and one of his students first made a remarkable discovery...
The Galápagos Islands site in Ecuador was inscribed on the World Heritage List in 1978. Located in the equatorial Pacific Ocean nearly 1000 km from South America, the Galapagos Islands and the...
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