Crawling and righting behavior of the subtropical sea star Echinaster (Othilia) graminicola: effects of elevated temperature
Sea stars exhibit discrete neuromuscular-mediated behaviors, such as crawling and righting, which are critical to daily functioning and survival. As global seawater temperatures rise, subtidal asteroids such as Echinaster (Othilia) graminicola on the Gulf Coast of Florida are increasingly subjected to elevated temperatures, which may compromise their neuromuscular health. To better understand the neuromuscular biology of E. graminicola and the effects of elevated seawater temperature on behavior, we first describe their righting mechanism and identify the arms used in righting and crawling. Together, this allowed us to determine if they exhibit any bilateral tendencies, related to their anterior–posterior ancestry, by measuring the frequency with which each arm led in righting and crawling. To determine the effect of elevated seawater temperature on their described righting behavior, we tested the effects of acute (1 day) and chronic (7 day) exposure to seawater temperatures ranging from 28 to 36 °C on righting time in a laboratory experiment. We found that E. graminicola rights by somersaulting, but exhibits no lead arm preference during this behavior. In crawling, Arm E, located adjacent to the madreporite, led most frequently, indicating a partial tendency toward bilateralism. Sea stars righted significantly faster with increasing temperature and exposure time as temperatures increased from 28 to 34 °C, suggesting some capacity for acclimatization to elevated temperatures. However, at 36 °C, righting time increased dramatically and sea stars experienced high mortality, suggesting E. graminicola may be living near the upper limits of its thermotolerance. As seawater temperatures rise beyond an organism’s thermal tolerance, their neuromuscular responses may become critically impaired, reducing their capacity to survive in a warming ocean.
We thank William Szelistowski and Cory Krediet for their helpful suggestions toward improving this manuscript, John Ferguson for sharing his expertise on local Echinaster populations, and David Bennett for his assistance with the temperature experiments. We thank the anonymous reviewers for their constructive comments which helped improve this manuscript. This research was supported by the Ford Apprentice Scholars Program at Eckerd College.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. The collection and handling of sea stars were followed by the regulations and policies outlined in Special Activity License SAL-14-0780-SR, issued by the Florida Wildlife Conservation Commission, Tallahassee, Florida, USA.
- Brothers CJ, McClintock JB (2015) The effects of climate-induced elevated seawater temperature on the covering behavior, righting response, and Aristotle’s lantern reflex of the sea urchin Lytechinus variegatus. J Exp Mar Biol Ecol 467:33–38. https://doi.org/10.1016/j.jembe.2015.02.019 CrossRefGoogle Scholar
- Buccheri E, Foellmer MW, Christensen BA, Langis P, Ritter S, Wolf E, Freeman AS (2019) Variation in righting times of Holothuria atra, Stichopus chloronotus, and Holothuria edulis in response to increased seawater temperatures on Heron Reef in the southern GBR. J Mar Biol 2019:1–6. https://doi.org/10.1155/2019/6179705 CrossRefGoogle Scholar
- Clark AM, Downey ME (1992) Starfishes of the Atlantic. Chapman & Hall, LondonGoogle Scholar
- Hotchkiss FHC (2011) Table of ray identification schemes for nonluidiid Asteroidea. Marine and Paleobiological Research Institute. http://mprinstitute.org/PDF/Notulae_MPRI_1001_rev01.pdf. Accessed 15 April 2019
- Jennings HS (1907) Behavior of the starfish, Asterias forreri de Loroil. U Calif Publicat Zool 4:102–152Google Scholar
- Loeb J (1900) Experiments on Asteroids. In: McKeen Catell J, Beddard FE (eds) Comparative physiology of the brain and comparative psychology. G. P. Putnam’s Sons, New YorkGoogle Scholar
- NOAA/NDBC (2017) Station CLBF1—Clam Bayou, FL. National Data Buoy Center. http://ndbc.noaa.gov/station_page.php?station=clbf1. Accessed 15 April 2019
- Pörtner H-O, Karl D, Boyd PW, Cheung W, Lluch-Cota SE, Nojiri Y, Schmidt DN, Zavialov PO (2014) Ocean systems. In: Field CB, Barros VR, Dokken DJ, Mach KJ, Mastrandrea MD, Bilir TE, Chatterjee M, Ebi KL, Estrada YO, Genova RC, Girma B, Kissel ES, Levy AN, MacCracken S, Mastrandrea S (eds) Climate change 2014: impacts, adaptation, and vulnerability. Part A: Global and sectoral aspects. Contribution of working group II to the fifth assessment report of the Intergovernmental panel on climate change. Cambridge University Press, Cambridge, pp 411–484Google Scholar
- Rhein M, Rintoul SR, Aoki S, Campos E, Chambers D, Feely RA, Gulev S, Johnson GC, Josey SA, Kostianoy A, Mauritzen C, Roemmich D, Talley LC, Wang F (2013) Observations: ocean. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: the physical science basis. Contribution of working group I to the fifth assessment report of the Intergovernmental panel on climate change. Cambridge University Press, Cambridge, pp 255–316Google Scholar
- Turner RE (2003) Coastal ecosystems of the Gulf of Mexico and climate change. In: Ning H, Turner RE, Doyle T, Abdollahi KK (eds) Integrated assessment of the climate change impacts on the Gulf Coast region. Gulf Coast Climate Change Assessment Council, WashingtonGoogle Scholar
- Turner RL (2013) Echinaster. In: Lawrence JM (ed) Starfish: biology and ecology of the asteroidea. The John Hopkins University Press, Baltimore, pp 200–215Google Scholar
- Verrill AE (1869) On new and imperfectly known echinoderms and corals. Proc Boston Soc Nat Hist 12:381–391Google Scholar