Ophiura sarsii

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Ophiura sarsii
Dorsal side of O. sarsii
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Ophiurida
Family: Ophiuridae
Genus: Ophiura
Species:
O. sarsii
Binomial name
Ophiura sarsii
Lütken, 1855

Ophiura sarsii or the notched brittle star is a benthic, marine, cold-water species of brittle star found commonly in the Arctic and Sub-Arctic seas.[1] This species was discovered by Christian Frederik Lütken in 1855. They are commonly red or brown.

Ophiura sarsii is a large and abundant species that can live for up to 27 years. They live on soft sediment in the bathypelagic zone of the ocean. They are trophic generalists but mostly feed on amphipods, and are the primary prey of many larger fish and crabs. They are hypothesized to colonize red king crabs in order to avoid predation. O. sarsii limbs are used for anti-allergenic and anti-inflammatory medication, and may be able to be used in order to create an anti-HIV medication. Their distribution and biomass have been greatly affected by climate change, but some subspecies may be regulating their gene expression differently in order to combat this.

Morphology

Adult O. sarsii have arms that can extend up to 90 millimeters or 3-4 times the disk size. Their central disks are commonly up to 25 millimeters in diameter but can be as large as 40 millimeters in diameter. [2] Their disk is rigid and heavily calcified.[3] This is much larger than the species Ophiocten sericeum, a different species of cold water brittle star that inhabits the same habitats. O. sericeum only has a maximum disk size of 18 mm.[4] As it transitions out of its larval stage, the central disk becomes a pentagonal shape with small perforations. As it continues to grow, it gains spines, arms and arm joints, as well as protective plates.[5]

Growth

This species of brittle star can live for up to 27 years. It has been found that they have an 8-year period of fast growth followed by a 4-5 year period of no growth, then a period of fast growth until their death. Growth in brittle stars can be measured using the growth bands on their disks.[4]

Habitat

They have been found in the northern parts of the Atlantic and Pacific Oceans, as well as the entirety of the Arctic Ocean. [2] Their distribution is primarily in the bathyal zone of the open ocean, in some parts covering as much as 96% of the seabed.[6] In the Arctic sea, they mostly inhabit slopes and shelves with soft bottoms.[7] They have been found to outnumber all other brittle star species in their habitat, making up 71% of the abundance in the benthic and epibenthic parts of the Arctic Ocean.[4]

Diet and feeding habits

Prey

They are primarily carnivorous, feeding on mostly amphipods. But they have also been found to eat arthropods, molluscs, cnidarians and annelids making them trophic, generalist feeders. However, their diet is mostly restricted to the amphipod families Ampeliscidae and Lysianassidae, which made up 54-70% of their stomach contents in during sampling periods in an experiment done by Harris et al., 2009.[2]

Predators

O. sarsii are prey of benthic carnivorous fish and crab species. [8][9] They are the main prey of the American Plaice in the Gulf of Maine, with one study by Packer et al. (1994) finding that 82% of their gut contents were made up of ophiuroids, 65% of which were O. sarsii.[3] Over 50% of adult red king crabs were also found to consume brittle stars like O. sarsii.[10]

Epibiosis

A study done by Dvoretsky & Dvoretsky, 2021 found that O. sarsii and other deep sea echinoderms were colonizing the red king crab in parts of the Barents Sea. Red king crabs are predators of O. sarsii and this study hypothesizes that they colonize these crabs to avoid predation. Possible consequences to the red king crab of this could be increased egg mortality and decreased gill efficiency if the colonizers crawl into their gills or onto their brood of eggs. However, infestations of O. sarsii and other echinoderms are only found in 0.7-1.1% of red king crabs.[10]

Human usage

When fresh O. sarsii tissue is collected, sulfated steroidal polyols can be isolated from it. These steroids can potentially be used for anti-HIV medication since they can inhibit some enzymes and cause cell death.[11] THA found in the limbs of them can be isolated into an anti-inflammatory and anti-allergenic substance. Since it is so abundant, they are widely used as a source of THA.[12] There are no known fisheries for O. sarsii and other Arctic brittle stars.

Impacts of climate change

Due to global warming, it appears as though O. sarsii has undergone a decrease in overall growth and biomass, especially in the Yellow Sea. This has been found to alter their distribution and behaviors.[8] The warming of the ocean can also result in proteins and enzymes unfolding inside O. sarsii DNA, since they are a cold-water species. However, a study done by Liao et al., 2025 found that a subspecies of O. sarsii may be able to stop the effects of global warming on their bodies by regulating gene expression.[13]

References

  1. Genelt-Yanovskiy, Evgeny; Li, Yixuan; Stratanenko, Ekaterina; Zhuravleva, Natalia; Strelkova, Natalia; Xu, Qinzeng; Nazarova, Sophia (2021-01-21). "Phylogeography of the Brittle Star Ophiura sarsii Lütken, 1855 (Echinodermata: Ophiuroidea) from the Barents Sea and East Atlantic". Diversity. 13 (2): 40. Bibcode:2021Diver..13...40G. doi:10.3390/d13020040. ISSN 1424-2818.
  2. Harris, Jennifer L.; MacIsaac, Kevin; Gilkinson, Kent D.; Kenchington, Ellen L. (August 2009). "Feeding biology of Ophiura sarsii Lütken, 1855 on Banquereau bank and the effects of fishing". Marine Biology. 156 (9): 1891–1902. Bibcode:2009MarBi.156.1891H. doi:10.1007/s00227-009-1222-1. ISSN 0025-3162.
  3. Packer, David B.; Watling, Les; Langton, Richard W. (1994-06-29). "The population structure of the brittle star Ophiura sarsi Lütken in the Gulf of Maine and its trophic relationship to American plaice (Hippoglossoides platessoides Fabricius)". Journal of Experimental Marine Biology and Ecology. 179 (2): 207–222. Bibcode:1994JEMBE.179..207P. doi:10.1016/0022-0981(94)90115-5. ISSN 0022-0981.
  4. Ravelo, Alexandra M.; Konar, Brenda; Bluhm, Bodil; Iken, Katrin (2017-05-01). "Growth and production of the brittle stars Ophiura sarsii and Ophiocten sericeum (Echinodermata: Ophiuroidea)". Continental Shelf Research. 139: 9–20. Bibcode:2017CSR...139....9R. doi:10.1016/j.csr.2017.03.011. hdl:10037/13882. ISSN 0278-4343.
  5. Sumida, Paulo Y. G.; Tyler, Paul A.; Gage, John D.; NøRrevang, Arne (November 1998). "Postlarval development in shallow and deep-sea ophiuroids (Echinodermata: Ophiuroidea) of the NE Atlantic Ocean". Zoological Journal of the Linnean Society. 124 (3): 267–300. doi:10.1111/j.1096-3642.1998.tb00577.x.
  6. Fujita, Toshihiko; Ohta, Suguru (1990). "Size structure of dense populations of the brittle star Ophiura sarsii (Ophiuroidea: Echinodermata) in the bathyal zone around Japan". Marine Ecology Progress Series. 64 (1/2): 113–122. Bibcode:1990MEPS...64..113F. doi:10.3354/meps064113. ISSN 0171-8630. JSTOR 24844596.
  7. Sswat, M.; Gulliksen, B.; Menn, I.; Sweetman, A. K.; Piepenburg, D. (2015-06-01). "Distribution and composition of the epibenthic megafauna north of Svalbard (Arctic)". Polar Biology. 38 (6): 861–877. Bibcode:2015PoBio..38..861S. doi:10.1007/s00300-015-1645-8. ISSN 1432-2056.
  8. Hu, Xuying; Li, Yixuan; Dong, Yue; Liao, Xiaomei; Zhang, Qian; Mou, Anning; Li, Xinlong; Zhang, Xuelei; Xu, Qinzeng (2025-05-01). "Population characteristics of the dominant cold-water brittle star Ophiura sarsii vadicola (Ophiurida, Ophiuroidea) in the Yellow Sea". Journal of Oceanology and Limnology. 43 (3): 865–877. Bibcode:2025JOL....43..865H. doi:10.1007/s00343-024-4003-2. ISSN 2523-3521.
  9. Orino, Kazuki; Ishigane, Kosuke; Suzuki, Kota; Izumiura, Hiroki; Nakaya, Mitsuhiro; Takatsu, Tetsuya (2019-07-01). "Growth of the brittle star Ophiura sarsii sarsii in Funka Bay, Hokkaido, Japan". Fisheries Science. 85 (4): 705–716. Bibcode:2019FisSc..85..705O. doi:10.1007/s12562-019-01323-1. hdl:2115/78529. ISSN 1444-2906.
  10. Dvoretsky, Alexander G.; Dvoretsky, Vladimir G. (2021-03-23). "New Echinoderm-Crab Epibiotic Associations from the Coastal Barents Sea". Animals. 11 (3): 917. doi:10.3390/ani11030917. ISSN 2076-2615. PMC 8004836. PMID 33807022.
  11. Fedorov, Sergey N.; Levina, Eleonora V.; Kalinovsky, Anatoly I.; Dmitrenok, Pavel S.; Stonik, Valentin A. (December 1994). "Sulfated Steroids from Pacific Brittle Stars Ophiopholis aculeata, Ophiura sarsi, and Stegophiura brachiactis". Journal of Natural Products. 57 (12): 1631–1637. Bibcode:1994JNAtP..57.1631F. doi:10.1021/np50114a004. ISSN 0163-3864.
  12. Fujita, Toshihiko; Ohta, Suguru (1989-10-01). "Spatial structure within a dense bed of the brittle starOphiura sarsi (Ophiuroidea: Echinodermata) in the bathyal zone off otsuchi, Northeastern Japan". Journal of Oceanography. 45 (5): 289–300. Bibcode:1989JOce...45..289F. doi:10.1007/BF02123483. ISSN 1573-868X.
  13. Liao, Xiaomei; Li, Xinlong; Mou, Anning; Zhang, Qian; Dong, Yue; Li, Yixuan; Zhang, Xuelei; Xu, Qinzeng (2025-05-01). "Thermal acclimatization mechanisms in the cold-water Ophiuroid Ophiura sarsii vadicola: Regulation of protein homeostasis and metabolic pathways". Journal of Thermal Biology. 130 104137. Bibcode:2025JTBio.13004137L. doi:10.1016/j.jtherbio.2025.104137. ISSN 0306-4565. PMID 40413918.