Back to the past, looking for sea urchins and other deep sea life
Back to the past, looking for sea urchins and other deep sea life Sea urchin (Araeosoma belli) with poison sacs on the end of its spines. (Lower, left) Zoologist Dave Pawson ready to descend in a submersible for a deep sea dive. (Smithsonian/Dave Pawson)
Back to the past, looking for sea urchins and other deep sea life
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While this animal looks like a pincushion, you would not find it in a sewing kit. This venomous sea urchin is also called A. belli. It lives on the ocean bottom as deep as several thousand meters. Scientists study it and other deep ocean dwellers. They use submersibles. They also use remotely operated vehicles (ROVs). These vehicles explore the ocean depths equipped with cameras and collecting gear. 

But, original observations of these deep-water urchins were made before research submersibles or ROVs were in use. How did scientists back then learn about animals that lurked way beyond the reach of scuba gear?

Ole Theodor Jensen Mortensen was one such scientist. He was a Danish zoologist. In 1938, he described the stomach contents of relatives of A. belli. It had been brought to the surface by a trawling ship.

He was not able to observe the animals alive in their deep habitat. But the remarkable observation of plant material inside their bodies led him to propose that some sea urchins were vegetarians. These individuals had apparently fed on plants. These plants had broken off from shallow sea grass beds. Or they floated down rivers, then drifted down to the deep sea. 

Decades later, Mortensen’s discovery was confirmed by other scientists. One such scientist was Dave Pawson. He is a Smithsonian Zoologist. Pawson found sea grass in specimens of A. belli. The specimens are from the historic US Fish Commission Steamer Albatross. It was the first dedicated U.S. ocean research ship. It made expeditions from 1883-1921. Trawling with long nets for months, the Albatross collected millions of specimens. They were often from great depths. Aboard the Albatross in 1906 was a young Austin Clark. He was the ship's lead naturalist. Among the animals Austin catalogued were hundreds of species of sea urchins and relatives. They greatly expanded the echinoderm collection at the Smithsonian’s “U.S. National Museum.”  

Echinoderms also include sea stars and sea cucumbers. They include brittle stars and crinoids. Their diverse body shapes reflect the range of marine habitats they occupy. They may occupy shallow reefs to deep ocean bottom. Sea urchins do justice to the name (echino = “spiny”; derm = “skin”). But other echinoderms may be soft. They may be smooth or feathery. Or they may be bumpy. What they all have in common is a body with five-part symmetry. This is obvious in a five-armed sea star. But it is hidden under the skin of a sea cucumber. Austin Clark, in his later work at the U.S. National Museum, described nearly 500 new species of echinoderms. 

Today, scientists continue to study echinoderms, probing mysteries about their life histories. Zoologist Dave Pawson works at what is now called the National Museum of Natural History. He combines data from museum specimens, research at sea, and observations of live animals. He looks to see what echinoderms reveal about life in the deep sea and its connection to shallow-water habitats. Learn more about his discoveries in a "Smithsonian Science How" webcast video. During “A Century of Discovery of Sea Urchins and Relatives,” Dave will take you on a historical research journey. You can also get teaching resources to use with the webcast.

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Why was it more difficult to study the deep sea when these sea urchins were first discovered?
Write your answers in the comments section below

  • keidene-orv
    10/26/2017 - 02:47 p.m.

    this sounds very scary i don't what to find that thing at the wrong place or time i wonder if there are other things down there

    • LamontO-mie
      11/15/2017 - 02:45 p.m.

      I wish i could see the animal in real life in a tank

  • charlottew-
    10/28/2017 - 08:29 a.m.

    I think that this article is very interesting. I love reading about animals and new sea life.I thought that it was telling us how scientist used to look and creatures that they couldn't reach.

  • Sophia-E2
    11/01/2017 - 10:50 a.m.

    Some people found a new type of sea urchin! The sea urchin is venomous the sea urchin is called A. Belli. It lives several thousands of meters down on the ocean floor. To see these creatures they must use a submersible. They also use ROV's the vehicle go down to the ocean floor with cameras and other equipment.

    MY COMMENTS: I think that it is cool that they found another sea urchin and it is weird that they call it A. Belli.

  • ChrisM-mac2
    11/03/2017 - 09:57 a.m.

    they are found at very deep depths of the ocean were only submersibles could go down and study.

  • 24mgblum
    11/13/2017 - 11:05 a.m.

    Cool! I really lie new sea life. I also love anything science. You never know what else they might find. I didn't know alot of this info before.

  • 24crkutc
    11/13/2017 - 11:08 a.m.

    Because they didn't have the technolgy they have now. It was very hard to go down into the sea because they didn't have the right technolgy. But now they do have the technolgy to look under the sea.Now we can see what is on the ocean floor. Now we can discover more on the ocean floor.

  • 24lmsove
    11/14/2017 - 10:24 a.m.

    It was so difficult because they would need to go down in a submarine. I also think sea life very cool. My favorite kind of sea life is sea turtle. I think the name belli is so cool also. I wonder what else they could find down there.

  • 24kmjohn
    11/14/2017 - 10:36 a.m.

    *You should really have a picture of a belli.
    *Also a picture of a sea cucumber.
    *Why did the government decide to do research on a belli?
    *What is a sea cucumber?
    *Bellis are so cute and adorable!!!
    *I think they said on paragraph 2 or 3 they said that they didn't invent the ROV so they couldn't see their habitat.

  • 24lclabo
    11/14/2017 - 10:39 a.m.

    It was difficult to study the deep sea because they only had scuba gear, and not the latest technology they have now. A new kind of sea creature is very interesting. I love science and when new things come out I am excited to read or learn above them. I wonder what other sea creatures live in the depths of the ocean that we haven't discovered yet...

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