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Description:
Brittle Stars are said to have gotten their name from the fact that they detach their limbs when scared and alarmed. This particular Brittle Star, Ophiothela mirabilis is apart of the genus Ophiothela in the class Ophiuroidea, which is derived from the Greek word ophis, which means snake. The name refers to the snake like features of the movements of an Ophiuroidea’s arms during locomotion. Unlike most brittle stars that are pentamerous, that meaning five armed, the Ophiothela mirabilis is a six armed brittle star. Ophiothela mirabilis are a small epizoic (non parasitic) that can range from orange to yellow in color within the Atlantic Ocean (Mantelatto, Marcelo Checoli, et al., 2016). Within the Pacific Ocean, researchers have found that these brittle stars have a greater variety of color, which can range from purplish to cream to yellow. This suggests that because the brittle stars within the Atlantic are yellow to orange that they belong to a single lineage ((Hendler et al. 2012)).
Anatomy:
On average the Ophiothela mirabilis body size is small. The lobulated disk on Ophiothela miabilis is relatively small and range from 1.3 to 4.3 mm in disk diameter (Mantelatto, Marcelo Checoli, et al., 2016). The disks of these Brittle Stars contain various grains and a ventral arm, which is separated by the lateral plates; the arms of the Ophiothela mirabilis also have well developed hooks at their tips (Fernández et al. 2014).
Ophiothela mirabilis A dorsal view. Scale bar = 5 mm B dorsal view of the arm C ventral view of the arm D dorsal view of the disk E ventral view of the disk F jaw. Scale bar = 1 mm.
Reproduction in Ophiothela mirabilis:
There is very little that is known about how the Ophiothela mirabilis reproduce sexually because of the lack of investment put into research. However, there is more information known about how the Ophiothela mirabilis reproduce asexually. Ophiothela mirabilis are known to reproduce asexually by fissiparity. This meaning that the Ophiothela mirabilis are separating their bodies in half down the middle and are able to regenerate their missing halves (Waters, 2016).
Habitat:
Ophiothela mirabilis were originally founded within the Pacific Ocean. Not only were they originally founded in the Pacific Ocean, but they were also thought to be restricted within the Pacific Waters as well. However, in more recent times within the 21st century, Ophiothela mirabilis have been found to be in the Atlantic Ocean as well. Ophiothela mirabilis tend to live on host species, which is why they are known as being epizoic. Epizoic is used for a species that is not parasitic to the host they are living on. Ophiothela mirabilis can be primarily found on gorgonians where they use their hooked spines to wrap their arms around the gorgonians (Mantelatto, Marcelo Checoli, et al., 2016). There were are least 20 different other species that are known to host these Ophiothela mirabilis with in the Atlantic as well which include five cnidarians, seven sponge species, and five ascidians.
Cnidarians used by Ophiothela mirabilis (arrowed): (a) Heterogorgia uatumani, (b) Leptogorgia punicea, (c) Carijoa riisei, (d) Leptogorgia setacea and (e) Palythoa caribaeorum. Images a and b photographed at Morcegos; b, c and eat Abraãozinho right. Scale bars: 2 cm
Invasive Species:
Ophiothela mirabilis is not very common around the world as being known as an invasive specie. However, the Ophiothela mirabilis is most definitely an invasive specie. The Ophiothela mirabilis’ root of origin is within the Pacific Ocean. In the year 2000, Ophiothela mirabilis were found off the coast of Brazil (Hendler et al. 2012). First Ophiothela mirabilis were reported in Ilha do Pai, Rio de Janeiro State but soon the populations of these brittle stars spread further to areas such as French Guiana, St. Vincent and Tobago (Mantelatto, Marcelo Checoli, et al., 2016). Due to Ophiothela mirabilis being found in the presence near both Brazilian and Caribbean ports, which were about 4,500 km apart from each other the Ophiothela mirabilis is thought to have spread by ships. Since there is very little is known about the sexual reproduction of these Brittle Stars scientist do not know if a larval stage is present in development which would allow these Brittle Stars to be carried by currents and by sailing boats more easily. These Brittle Stars are also making themselves at home on various sponges, gorgonians and coral. Since these Ophiothela mirabilis that have made their way into the Atlantic Ocean are not suppose to be there or are not originally from the Atlantic Ocean they do not have any natural predators. Because there are no natural predators for these Ophiothela mirabilis the populations for this species is only increasing within the Atlantic. Currently, scientists have not found any bad correlations with having these brittle stars move into the Atlantic Ocean. However, researchers say that with this change in the environment it cannot possibly be good for the overall ecosystem. Even more research is being done in order to understand the affects of having large population of these invasive brittle stars moving into the Atlantic Ocean.
Records, with timeframe, of Ophiothela mirabilis in the southwest Atlantic and Caribbean
Citations:
Granja-Fernández R, Herrero-Pérezrul MD, López-Pérez RA, Hernández L, Rodríguez-Zaragoza FA, Jones RW, Pineda-López R (2014) Ophiuroidea (Echinodermata) from coral reefs in the Mexican Pacific. ZooKeys 406: 101–145. doi: 10.3897/zookeys.406.6306
Hendler, G., Migotto, A.E., Ventura, C.R.R. et al. Coral Reefs (2012) 31: 1005. doi:10.1007/s00338-012-0936-6
Hendler, Gordon, and Sophie J. Brugneaux. "New records of brittle stars from French Guiana: Ophiactis savignyi and the alien species Ophiothela mirabilis (Echinodermata: Ophiuroidea)." Marine Biodiversity Records, vol. 6, 14 Sept. 2013, doi:10.1017/S1755267213000845. Accessed 1 Dec. 2016.
Mantelatto, Marcelo Checoli, et al. "Host species of the non-indigenous brittle star Ophiothela mirabilis (Echinodermata: Ophiuroidea): an invasive generalist in Brazil?" Marine Biodiversity Records, vol. 9, no. 1, 30 Mar. 2016, pp. 1-7. EBSCO host, DOI:10.1186/s41200-016-0013-x. Accessed 1 Dec. 2016.
Texas Invasive Species Institute. "INVASIVE BRITTLE STAR." Texas Invasive Species Institute, www.tsusinvasives.org/home/database/ophiothela-mirabilis. Accessed 1 Dec. 2016.
Waters, Hannah. "An Invasive Brittlestar." Ocean Portal | Smithsonian. Smithsonian, 23 Aug. 2016. Web. 02 Dec. 2016.
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