Image: Ocean salps
Kelly Sutherland and Larry Madin, WHOI
Salps can exist as a single individual or chains of 100 or more, shown here drifting through the twilight midocean waters with a small fish.
updated 8/10/2010 11:22:40 AM ET 2010-08-10T15:22:40

Small bloblike creatures may be the ocean's most efficient feeders, a new study suggests.

The salp, a 5-inch-long, barrel-shaped organism that resembles a streamlined jellyfish, lives in mid-ocean waters where it filters the seawater for food particles.

"We had long thought that salps were about the most efficient filter-feeders in the ocean," said study researcher Larry Madin, director of research at Woods Hole Oceanographic Institution in Massachusetts.

But the new results show these animals can consume particles that span a huge size range, or about four orders of magnitude. If sized up that range would be like eating everything from a mouse to a horse, Madin said.

The finding, published this week in the journal Proceedings of the National Academy of Sciences, "implies that salps are more efficient vacuum cleaners than we thought," said study researcher Roman Stocker of MIT.

Mucus trap
Salps, which can live for weeks or months as single globs or chains of 100 or more individuals, swim and eat in rhythmic pulses, each of which draws seawater in through an opening at the front end of the animal. A nanometer-scale mucus net captures the food particles, mostly phytoplankton, which ends up in the gut where they get digested.

Until now, it was thought the 1.5-micron-wide holes in the mesh meant only particles larger than that got captured, while smaller particles would slip through the mucus net. (For comparison, the diameter of a human hair is about 100 microns.)

But a mathematical model suggested salps somehow might be capturing food particles smaller than that, said study researcher Kelly Sutherland, then working on her Ph.D. at MIT and WHOI.

In the laboratory at WHOI, Sutherland and her colleagues offered salps food particles of three sizes: smaller, around the same size as, and larger than the mesh openings.

"We found that more small particles were captured than expected," said Sutherland, now a post-doctoral researcher at Caltech. "When exposed to ocean-like particle concentrations, 80 percent of the particles that were captured were the smallest particles offered in the experiment."

Salp survival
The finding helps explain how salps can survive in the open ocean where the supply of larger food particles is low.

In addition, the results reveal the importance of the salps in carbon cycling. Scientists believe its waste material may help remove carbon dioxide (CO2) from the upper ocean and the atmosphere.

After eating both small and large particles, the animals release waste that consists of these particles packed into larger, denser globs.

The larger and denser the carbon-containing pellets, the sooner they sink to the ocean bottom. "This removes carbon from the surface waters, and brings it to a depth where you won't see it again for years to centuries," Sutherland said.

The research was funded by the National Science Foundation and the Woods Hole Oceanographic Institution Ocean Life Institute.

© 2012 All rights reserved.

Photos: All creatures under the sea

loading photos...
  1. Silent scream

    When attacked by a predator, this deep-sea jellyfish (Atolla wyvillei) uses bioluminescence to "scream" for help. The amazing light show is known as a burglar alarm display. This jellyfish was photographed by the ROV Hyper Dolphin east of Japan's Izu-Oshima Island, 2,640 feet (805 meters) below the surface. (JAMSTEC) Back to slideshow navigation
  2. Diversity in the deep

    The Census of Marine Life is aimed at cataloging as many species of sea creatures as possible. This is a Venus flytrap sea anemone (Actinoscyphia sp.) from the Gulf of Mexico. Its common name includes references to two terrestrial plants ("Venus flytrap" and "anemone"), but the species is classified as a type of polyp. It closes its tentacles to capture prey or protect itself. (I. MacDonald, D.L. Felder and D.K. Camp) Back to slideshow navigation
  3. Octopus in the Gulf

    A deep-water octopus (Benthoctopus sp.) sits on the seafloo in the Gulf of Mexico's Alaminos Canyon, about 8800 feet (2700 meters) beneath the sea surface. (I. MacDonald, D.L. Felder and D.K. Camp) Back to slideshow navigation
  4. Neighbor to an oil rig

    This queen angelfish (Holacanthus ciliaris) was spotted near an oil rig in the Gulf waters off the coast of Texas. (G. Haralson / I. MacDonald, D.L. Felder and D.K. Camp) Back to slideshow navigation
  5. Cooper of the Sea

    This Gulf of Mexico amphipod, Phronoma sedentaria, is known as the "Cooper of the Sea" because the crustacean species lives inside a barrel-shaped creature known as a salp, also shown here. (H. Bahena / I. MacDonald, D.L. Felder and D.K. Camp) Back to slideshow navigation
  6. King of the hydroids

    Branchiocerianthus imperator is the largest known type of solitary hydroid. Hydroids look like flowers, but they're actually animals with tentacles. This one was spotted by the HOV Shinkai 2000 in Japan's Sagami Bay at a depth of 2,200 feet (670 meters). (JAMSTEC) Back to slideshow navigation
  7. Star of the sea

    Asteronyx loveni is a type of brittle star that tends to cling onto another marine species known as the sea pen. This brittle star was spotted with its arms flung wide in Japanese waters off Sanriku, at a depth of 4,150 feet (1,265 meters). (JAMSTEC) Back to slideshow navigation
  8. Spiky spider

    The spider conch (Lambis chiragra) has six spines on the lip of its shell. The shell's pearly interior displays beautiful tints of orange and yellow. The species is listed as "vulnerable" on the Red List of threatened animals of Singapore. (Shaoqing Wang) Back to slideshow navigation
  9. Boneworms at work

    Osedax worms, more commonly known as boneworms, consume bones on the seafloor. The reddish feathery plumes act as gills. All Osedax males are dwarfs and live on the trunks of females. (Yoshihiro Fujiwara / JAMSTEC) Back to slideshow navigation
  10. Paper bubble

    This red-lined paper bubble (Hydatinidae gen. sp.) was discovered in a sperm whale carcass in the Kagoshima whale fall, off Japan's Cape Nomamisaki. The gastropod's tiny eyes are protected by cephalic shields. The "paper bubble" is actually an extremely thin shell. (Yoshihiro Fujiwara / JAMSTEC) Back to slideshow navigation
  11. Dangerous beauty

    The giant Caribbean anemone (Condylactis gigantea) grows to a height of about 6 inches (15 centimeters). Its tentacles are beautiful ... but they contain toxin-bearing nematocysts that paralyze the sea anemone's prey. (Eduardo Klein) Back to slideshow navigation
  12. Fire in water

    The bearded fireworm (Hermodice carunculata) is a type of bristleworm, with groups of white bristles along each side. The venom-filled bristles easily penetrate the flesh and break off if this worm is handled. They produce an intense burning sensation in the area of contact, hence the common name of the Caribbean species. (Eduardo Klein) Back to slideshow navigation
  13. Spongebob's buddy

    These nocturnal echinoderms (Ophiothrix suesonii) are called sponge brittle stars. They are very common in the Caribbean. They are so named because they are found exclusively either inside or outside living sponges. (César Herrera) Back to slideshow navigation
  14. What big teeth!

    Imagine living in the sea where it is permanently dark, cold, and food is hard to find. For many animals at depth, it may be weeks to months between meals. If you find something to eat, you have to hang on to it. This is why so many deep-sea fishes have lots of big teeth. This dragonfish, spotted off the coast of Australia, even has teeth on its tongue. They would be terrifying animals ... if they weren’t the size of a banana. (Julian Finn / Museum Victoria) Back to slideshow navigation
  15. Fish with a lure

    The sargassumfish (Histrio histrio) is a member of the frogfish family (Antennariidae), a group of small, globular fishes with stalked, grasping, limblike pectoral fins with small gill openings behind the base, a trapdoor-like mouth high on the head, and a "fishing lure" (formed by the first dorsal spine) on the snout. It typically lives in open waters in close association with floating sargassum weed (Sargassum natans and S. fluitans) but is frequently blown into nearshore and bay waters during storms. This specimen was found off the coast of Korea. (Dr. Sung Kim) Back to slideshow navigation
  16. The males of Leptocheliidae have legs that are larger than those of the females, in some cases significantly exceeding the body length. While the legs are normally held folded, they are extended fully forward during swimming. The extremely slender legs found in the Leptochelia minuta group are unlikely to be capable of any feeding or locomotory function. This specimen was collected from the waters off Australia's Lizard Island. (Magda Blazewicz-paszkowycz) Back to slideshow navigation
  17. Kooky cucumber

    This newly discovered sea cucumber species, Elpidia belyaevi, was first found in the Arctic deep sea. (Antonina Rogacheva) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  4. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.


Discussion comments


Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments