Eucidaris galapagensis
| Eucidaris galapagensis | |
|---|---|
| |
| Cidaroid urchin in Galapagos | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Order: | Cidaroida |
| Family: | Cidaridae |
| Genus: | Eucidaris |
| Species: | E. galapagensis
|
| Binomial name | |
| Eucidaris galapagensis Döderlein, 1887
| |
Eucidaris galapagensis, commonly referred to as the slate pencil sea urchin, is a species of echinoderms in the family of Cidaroid.[1] This sea urchin lives in coastal areas in the Galapagos, Clipperton, and Cocos. The preferred substrate of these organisms is rocky, benthic environments that provide refuge.[2] In fact, greater abundance of Slate Pencil Sea Urchins is correlated with correct substrate, as well as greater food availability.[3] Their diet is primarily herbivorous, however, they also consume various invertebrates. They graze heavily on live corals and algae in open, shallow reef habitats.[4] Their grazing schedule is not restricted to sunlight availability, and will graze nocturnally.[4] Their diversity in diet is a result of their metabolism, as they are capable of remarkably efficient assimilation of nutrients.[2] Pencil Slate Sea Urchin's crawl omnidirectionally in their environment.[5] Additionally, they are able to sense surrounding light by photoreceptor cells that act as their visual system.[6]
Biological importance
[edit]Echinoderms are critical components of marine communities, and Eucidaris Galapagensis is no different.[3] The spines of the urchins provide habitat to diverse epifauna and act as a reservoir for diversity.[7] The abundance of Eucidaris galapagensis is important, as they provide substrate and refuge from predators.[7] Additionally, they exhibit a top-down control in the Galápagos Marine Reserve, and their presence may alter the sessile community composition.[8] A significant amount, 90%, of the spines of the urchins are encrusted with diverse epifauna, and one urchin can host over 20 species.[2] An interesting aspect of this reservoir is the potential of dispersal. Urchins are mobile organisms, they have the potential to redistribute the redistributed epifauna. However, when these urchins reach a great abundance, they are capable of causing a trophic cascade.
Anthropogenic impacts
[edit]Climate events
[edit]As ectothermic organisms, Eucidaris Galapagensis, can be greatly impacted by climate events, such as El Nino's and climate change.[9] In warmer environments, the metabolism and fitness of urchins can be population specific.[9] Eucidaris Galapagensis are adapted and acclimated to short-term, local temperature fluctuations, and they have substantially greater thermal tolerances.[9] Further, the grazing pressure of Eucidaris Galapagensis can exasperate the effect of climate events.[10] Habitats suffering from climate impacts can be infiltrated by Eucidaris Galapagensis, resulting in “Urchin Barrens”, which are desolate, overgrazed coralline reefs that are replaced with algae.[10] In fact, these events can lead to expansion of grazing urchins.[10] An overabundance in urchins can interfere with the establishment of reef structure and, therefore, reduce reef growth.[4]
Fishing
[edit]When fishing presence is not a threat, Eucidaris Galapagensis will exhibit larger size and ubiquitous occurrence.[3] As a consequence, the Slate Pencil Sea Urchin population is maintained through predation, however, when the number of predators decreases as a result of fishing pressure, urchin density can increase.[11] Historically, the removal of lobster and fish predators enhances the impacts of El Niño through the expansion of grazing Eucidaris galapagensis.[12] This is why it is critical for fishing management to be proactive in reducing bycatch and excessive catch.
Related species
[edit]Eucidaris Galapagensis was once identified as Eucidaris thouarsii, however due to genetic analysis, it is now recognized as a separate species.
References
[edit]- ^ "Eucidaris galapagensis" at the Encyclopedia of Life
- ^ a b c Altieri, A.H. & Witman, J.D. 2014. Modular mobile foundation species as reservoirs of biodiversity. Ecosphere. 5(10): pp. 1-11
- ^ a b c Lawrence, J.M. & Sonnenholzner, 2004. Distribution and abundance of asteroids, echinoids, and holothuroids in Galapagos. Echinoderms: Munchen: Proceedings of the 11th International Echinoderm. 11: pp. 239-242
- ^ a b c Glynn, P.W. Wellington, G.M. and Birkeland, C. 1979. Coral reef growth in the Galapagos: limitation by sea urchins. Science. 203: pp. 47-49.
- ^ Grabowsky, G.L. 1994. SYMMETRY, LOCOMOTION, AND THE EVOLUTION OF AN ANTERIOR END: A LESSON FROM SEA URCHINS. Evolution. 48: pp. 1130-1146.
- ^ Ullrich-Lüter, E.M., Dupont, S., Arboleda, E., Hausen, H., Arnone, M.I. 2011. Unique system of photoreceptors in sea urchin tube feet. Proceedings of the National Academy of Sciences May 2011. 108 (20): 8367-8372; DOI: 10.1073/pnas.1018495108
- ^ a b Altieri, A. H., and J. D. Witman. 2014. Modular mobile foundation species as reservoirs of biodiversity. Ecosphere. 5(10): p. 124
- ^ Sonnenholzner, J.I. Lada, L.B. and Lafferty, K.D. 2009. Cascading effects of fishing on Galapagos reef communities: reanalysis using corrected data. Marine Ecology Progress Series. 375: pp. 209-218
- ^ a b c Silva Romero, I., Bruno, J.F., Silbiger, N.J., & Brandt, M. 2021 Local conditions influence thermal sensitivity of pencil urchin populations (Eucidaris galapagensis) in the Galápagos Archipelago. Marine Biology. 168(34)
- ^ a b c Edgar, G.J., Banks, B.A., Brandt, M., Bustamente, R.H., Chiriboga, A., Earle, S.A., Garske, L.E., Glynn, P.W., Grove, J.S., Henderson, S., Hickman, C.P., Miller, K.A., Rivera, F., & Wellington, G.M. 2010. El Nino, grazers and fisheries interact to greatly elevate extinction risk for Galapagos marine species. Global Change Biology. 16(10): pp. 2876-2890
- ^ Sonnenholzner J.I., Ladah L.B., & Lafferty K.D. 2009. Cascading effects of fishing on Galapagos rocky reef communities: reanalysis using corrected data. Marine Ecology Progress Series. 375: pp. 209-218
- ^ Edgar, G.J. Banks, S.A. and Brandt, M.2010. El Nino, grazers and fisheries interact to greatly elevate extinction risk for Galapagos marine species. Global Change Biology. 16: pp. 2876–2890