Surprise in the Deep Sea: Researchers Discover Unexpected Paths on the Ocean Floor

Sponge Trails

This image shows trails left by sponges as they crawl across the seafloor. Credit: AWI OFOBS team, PS101

Sponges: They are considered to be one of the most primitive forms of animal life, because they have neither locomotion organs nor a nervous system. A team around deep-sea scientist Antje Boetius has now discovered that sponges leave trails on the sea floor in the Arctic deep sea. They conclude that the animals might move actively — even if only a few centimeters per year. They are now publishing these unique findings in the journal Current Biology.

The surprise was great when researchers looked at high-resolution images of the sea floor of the Arctic deep sea in detail: Path-like tracks across the sediments ended where sponges were located. These trails were observed to run in all directions, including uphill. “We conclude from this that the sponges might actively move across the sea floor and leave these traces as a result of their movement,” reports Dr Teresa Morganti, sponge expert from the Max Planck Institute for Marine Microbiology in Bremen. This is particularly exciting because science had previously assumed that most sponges are attached to the seafloor or are passively moved by ocean currents and, usually down slopes.

“There are no strong currents in the Arctic deep sea that could explain the structures found on the sea floor,” explains expedition leader Prof. Antje Boetius, who works together with deep-sea biologist Dr Autun Purser from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in the HGF-MPG Joint Research Group for Deep-Sea Ecology and Technology. The recently published recordings were made during an expedition at 87 °North at the Karasik Seamount about 350 kilometers away from the North Pole with the research icebreaker Polarstern in 2016 with a towed camera system OFOBS (Ocean Floor Observation and Bathymetry System). “With OFOBS we can create 3D models from the deep sea. The seamount’s summit was densely populated with sponges. 69 percent of our images showed trails of sponge spicules, many of which led to live animals,” reports Autun Purser.

Typical Sponge Spicule Trails

This figure shows typical sponge spicule trails. Credit: AWI OFOBS team, PS101; Morganti et al./Current Biology

Many questions arise from these observations: Why do the sponges move? How do they orient themselves? Possible reasons for locomotion could be foraging, avoiding unfavorable environmental conditions, or to distribute offspring. Searching for food in particular plays a major role in nutrient-poor ecosystems such as the Arctic deep sea. Sponges have an important function there anyway. As filter feeders they can utilize particle and dissolved organic matter and are intensively involved in nutrient and matter recycling by means of their bacterial symbionts. Sponges also provide arctic fish and shrimp useful structures to use as a habitat. However, the scientists still have to investigate the mechanisms of locomotion.

For more on this research, read Mysterious Ocean-Floor Trails Show Arctic Sponges on the Move.

Reference: “In situ observation of sponge trails suggests common sponge locomotion in the deep central Arctic” by Teresa M. Morganti, Autun Purser, Hans Tore Rapp, Christopher R. German, Michael V. Jakuba, Laura Hehemann, Jonas Blendl, Beate M. Slaby and Antje Boetius, 26 April 2021, Current Biology.
DOI: 10.1016/j.cub.2021.03.014

32 Comments on "Surprise in the Deep Sea: Researchers Discover Unexpected Paths on the Ocean Floor"

  1. platonicideal | May 1, 2021 at 5:56 am | Reply

    “Of course you forget, Peter, I was present at an unexplained, undersea, mass sponge migration.”

  2. Clyde Spencer | May 1, 2021 at 8:31 am | Reply

    In the absence of any obvious means of locomotion, have the researchers considered the possibility of the sponges being moved by some animal such as a dolphin, either playing, or trying to flush out fish or shrimp hiding in the sponge?

    • Think then speak | May 2, 2021 at 1:23 am | Reply

      The location rules out dolphins and the trails Are not consistent with flipping or pushing as sediment would be distributed differently (roll marks/piles at the side) or the sponges would be upside-down. Finally nearly all sponges in the video have this trail. Its highly unlikely a preditor would be so thorough as to move each and every one.

      TL/DR: yes people spent more than the 5 seconds you did jumping to dolphins under the freaking ARCTIC ICE CAPS.

      • Clyde Spencer | May 3, 2021 at 7:31 am | Reply

        Note that I did say, “such as.” I’m not a marine biologist, so I’m not intimately familiar with the range of all animals. But, I do know that seals, walrus, and whales — all air breathers — do forage “under the freaking ARCTIC ICE CAPS.”

        The article does not mention the depth, only that it was the top of a seamount, which could be shallow enough for marine mammals to reach.

        Your other points about the trails are germane and well taken. They would have been adequate.

        Your nome de plume is appropriate — as advice to yourself.

      • Backcountry164 | May 3, 2021 at 7:51 am | Reply

        Moved by something else is as plausible as anything offered in the article. “Foraging, avoiding unfavorable environmental conditions, or to distribute offspring”; a movement rate measured in cm per year obviously doesn’t accomplish any of those things…

      • Wow [think then speak]…they asked their question very nicely. No reason to do the whole tldr thing. Do you remember when teachers would say “no stupid questions”? That’s how people learn. You had 2 paths you could take there. You could’ve actually TAUGHT someone…or you could make them feel dumb for asking… Great choice.

    • That is a reasonable question. The story did say it was a deep sea camera yet, didn’t say at what depth this was found. Also, I think being pushed would have been a theory already investigated. Since it’s not in the story it was probably disproven as a probability.

  3. Silly scientists, anyone who has seen Sponge Bob knows they can move, talk and cook. They could have learned all this watching TV instead wasting millions of dollars on jaunts to the Arctic!

  4. Dolphins do not live in the artic nor can they handle water that deep. The pressure would kill them. Looking at the photos, i would say 100 percent guarenteed they are moving themselves.

  5. Dustin West | May 2, 2021 at 3:40 pm | Reply

    I know for a fact that at least one has legs and his name is spongebob squarepants. There is even video showing him using a pineapple for a shelter.

  6. Carol Taylor | May 3, 2021 at 11:01 am | Reply

    Ladies and gentlemen – truth is more important than one-up-manship. A gentle “no dolphins in the Arctic” should be sufficient. In the meantime let’s talk about how things without extremities move. I saw an entire 4 foot tall bush move two feet over a year. There was a drought but a minor backyard plumbing leak was supplying water about ten feet from the bush. Really happened in my backyard. We could say growing roots could help the bush move in a way growth in sponges might not but I suspect physical growth is the means movement is happening.
    What is promoting the movement? I can’t tell from the photos if all the paths are headed to a common area. Warmer currents with more food? Where are they headed and why? I bet old sponge divers have oral traditions re sponge movement.
    BTW, Sponge Bob’s creator graduated from Humboldt State in northern CA, my alma mater. He was a biology major with an art minor.

  7. Nottolazytolookitup | May 3, 2021 at 5:54 pm | Reply

    “One of the largest seamounts of the Gakkel Ridge is the Karasik seamount, discovered in 2001 and rising from a depth of 5000 m to 650 m.” Thank you Google.

  8. STAMPEDE!

  9. If sponges ate plastics!
    We use sponges to clean and filter…maybe the earth is being cleaned and filtered…?

  10. Thank you all! I have been so amused reading these comments. I know I’ll keep reading about scientific expeditions in hopes of finding more laughs.

  11. Anybody consider the Slug and Snails. Snails feasting on the micro nutrition on the aquarium glass…

  12. That’s was freaking hilarious!

  13. Transparency Report | May 4, 2021 at 3:49 am | Reply

    Those aren’t real pictures. At least not where they claim. I saw the paths that they are talking about before it got blurred out in Google Maps. The paths were much more mechanical in appearance, sometimes seeming to stop and make a perfect 90 degree angle turn. Sometimes would travel right into a ridge, I could tell because of the raised earth like you see in cartoons when Bugs Bunny tunnels. Mining the ocean floor perhaps? I know it’s not sponges, or swamp gas.

  14. They need a science degree for that?? Trails behind animal so animal move?? Box jelly can see without a nervous system, move intelligently. Etc.

  15. That was some alien poop

  16. These same trails and exactly the same pattern are located all over the place. Off the coast of western United States. Only they are literally massive across. No one researches sh*t. Just go over the same things again and again. Check our google earth. You’ll Sh*t.

  17. Scot Richardson | May 4, 2021 at 6:51 pm | Reply

    It’s freaking gold you idiots

  18. At least SpongeBob cartoon didnt lie that they are moving

  19. Jacob Maxfield | May 4, 2021 at 9:31 pm | Reply

    I’m reminded of the wandering stones I believe they’re in AZ. They basically move in a path the wind isn’t sufficient these are big rocks. It turns out to be the affect of frost forming and thawing unequally. I understand it’s underwater and pressure is high etc. Is there a chance sometimes a surface sub freezing current occasionally deposits some ice crystals near their bases. I know salt water lower freezing pt etc but I think it’s a thermodynamic effect I just don’t remember Marine invertebrate biology I wonder if there are frequently currents there that unevenly heat the sponges.

  20. Q: Why do the sponges move?
    A: to get to their job at the Krusty Krab, of course

  21. Wow [think then speak]…they asked their question very nicely. No reason to do the whole tldr thing. Do you remember when teachers would say “no stupid questions”? That’s how people learn. You had 2 paths you could take there. You could’ve actually TAUGHT someone…or you could make them feel dumb for asking… Great choice.

  22. Obviously heading to work at the Kristy Krab.

  23. Abdul Hanan...pakistan | May 6, 2021 at 8:14 pm | Reply

    These signs might be of any other thing….these signs cannot explain locomotion

  24. Abdul Hanan...pakistan | May 6, 2021 at 8:20 pm | Reply

    These signs might be of any other thing….these signs cannot explain locomotion,it is ludicrous…if i see a pen and some trails behind it,can i say that it showed locomotion

  25. Arne Hybertsen | May 6, 2021 at 11:58 pm | Reply

    De ser utsom gull nuggets som ligger over hele havbunnen!?

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