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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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 twenty years ago. Meet...
Several species of amphipod like this one, Gammarus wilkitzkii , live...
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Deep sea animals have to live in a very cold, dark, and high-pressure...
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In honor of Mother's Day, the Citizens of the Sea blog salutes ocean-going...

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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...
This 1837 sketch is Charles Darwin’s first diagram of an evolutionary tree. It appears in his First Notebook on Transmutation of Species (1837).
The blanket octopus can rip a poisonous tentacle from a Portuguese man-o-war and wield it like a sword to ward off enemies as it soars through the ocean trailing its webbed cloak behind it...
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...
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...
What makes a top predator? Razor-sharp teeth? Speed? Strength? Size? Who is the most fearsome hunter? It depends on where and when you look.
Bioluminescence is one of the more captivating adaptations that have evolved in marine animals. It's the ability of organisms to create and emit light. Dive underwater and you may witness lightshows...
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...
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...
Whales swim, but their ancestors walked. Whales are mammals (like us) whose ancestors lived on land. Life probably began in the ocean and then evolved to colonize the land. Yet the whale’s ancestors...
Dr. Stephen Cairns is a research zoologist and chair of the Department of Invertebrate Zoology at the Smithsonian’s National Museum of Natural History. His research focuses on the diversity,...
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...
Charles Darwin is so well known he almost needs no introduction. The 19th-century naturalist and geologist spent his life documenting and collecting information on the natural world . From birds to...
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...
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...
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...
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...
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...
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...
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