|
Ophiolepis superba (H.L. Clark, 1915) Banded Brittle Starfish
|
|
Angela Upton 2016
|
|
|
Summary |
Subsection 1 | |
Ophiolepis superba (H.L. Clark 1915) is a species of Ophiuroidea (brittle star) and follow the same general radially symmetrical body plan of a central disk and five distinct arms found in this class (Row & Gates 1995) (refer to section Physical Description for more details). This superficial similarity in body form found in all Brittle Stars has a high level of variability between different species though (Hendler et al. 1995). This variability is most evident in their major anatomical features such as the jaw structure, the scale positioning and size, and the spines (Hendler et al. 1995).
O. superba, commonly referred to as the Banded Brittle starfish, was first described in an article by Clark in 1915 then later in 1971 (Clark & Rowe 1971). For more details on its initial historical identifications refer to section Evolution and Systematic. Since then more detailed observations of the species have been made, especially with respect to other species, with intricate identification keys of the class as a whole being formed over the years (Hendler et al. 1995; Clarke and Rowe 1971).
In the class Opiuroidea there are currently over 2000 species identified, making it the largest and most diverse class of the entire phylum (Stöhr, O'Hara & Thuy 2012). This webpage is aimed at thoroughly investigating the key aspects of the species Ophiolepis superba through the accumulation of all relevant literature on it. This includes its physical description, aspects of its ecology, life history, behaviour, anatomy, bio-geographical distribution and more.
|
|
|
|
Physical Description |
|
2 - Markings and Colouration | |
This species is predominantly a beige or yellow-orange colour with very distinctive purple or black banding patterns along the arms and on the central disk (Stöhr, O’Hara & Thuy 2015). The patterning on the central disk is often highly variable between individuals with only pentaradial symmetry remaining relatively consistent. The individual observed in this study had a solid pentagon shaped marking, while other observed photos in the literature depict individuals with star shaped markings to ones with only five solid points (Stöhr, O'Hara and Thuy 2012; Cole 2007).
|
|
Figure 5 |
|
|
Figure 6 |
|
|
|
|
Ecology | |
The extent of this species ecological impact in minimum, as it is not a key stone species like a large predator it does not singularly impact its environment a great deal. Other species which consume larger prey, like commercially important crabs, would have a much bigger ecological impact. With their diet consisting of particles which settle on the ocean floor (refer to Feeding) the biggest ecological role this species may play would be its part in removing detritus and other organic matter. This would be helpful to the photosynthesizing organisms in its community which need a clear external surface to obtain any sunlight. However, the overall extent of the role this species has in its community has not yet been thoroughly investigated so only assumptions can be made.
|
|
|
Life History and Behaviour |
1 - Feeding | |
O. superba is a benthic feeder, eating food off the substrate via their tube feet and muscular arms (Hendler et al. 1995). Compared to some other brittle star species available in this study, O. superba is a lot less active and their reaction speeds appear comparatively slower then some other species from initial observations. This initiates that it would be unlikely for this species to be able to capture live prey. Additionally with its small body size many living prey would be too large to even attempt to consume it (Figure 7). O. superba would therefore most likely feed off of small particles falling to the ocean floor, detritus in particular (Hendler et al. 1995).
In the following video you can observe the movement of the tube feet and and oral tentacles around the mouth of the Banded Brittle Starfish:
|
O. superba ventral view
https://www.youtube.com/watch?v=Rbx5EzmwE5A
(video by Angela J. Upton)
|
|
|
Figure 7 |
|
|
|
2 - Locomotion | |
Ophiuroidea do have tube feet like most of their sister classes, however they do not utilize them for locomotion (Figure 8) (Lawrence 1987). They rely on the actions of their five multi-jointed limbs to move across the seafloor (Astley 2012; Romanes, 1885). Brittle Stars (and other Echinodermata classes) are unique benthic animals as they employ coordinated, bilaterally symmetrical movement despite lacking an anatomically defined anterior (Astley 2012). Despite their pentaradial symmetrical body form (refer to Physical Description Section) they are mobile along an axis of a central limb, which can be any one of its five, with synchronous motion of the remaining four (Astley 2012).
|
|
Figure 8 |
|
|
|
|
Anatomy and Physiology |
1 - Reproduction | |
This species is dioecious with indistinguishable genders externally, they most likely reproduce using their bursal cavity as a brooding chamber for their embryos to develop given this is what most Ophiolepis species do (Ruppert, Fox and Barnes 2004) The bursal slits leading to the bursal cavity are found ventraly next to the edges of each arm inside the central disk (Figure 10). Their larvae are therefore most likely planktotrophic, metamorphosising later on in life and eventually settling to the ocean floor (Ruppert, Fox and Barnes 2004).
|
|
Figure 9 |
|
|
|
|
|
Biogeographic Distribution | |
O. superba have been observed historically in a number of defined ranges, Clark and Rowe (1971) constructed a table of areas were this species is likely to occur within a depth limit of twenty meters. These areas are spread across the Indian and Pacific Ocean and grouped to highlight the specific shallow areas adjacent to the islands and major land masses in the visinity (Clark & Rowe 1971). These can be observed in figure 13 and correspond to the:
A. Minor Island of the western Indian Ocean
B. Mascarene Islands
C. East Africa and Madagascar*
D. The Red Sea*
E. The Arabian coast*
F. The Persian Gulf
G. West Pakistan and East India
H. The Maldive and Laccadive Islands*
I. Ceylon and the opposing Indian shores
J. The Bay of Bengal*
K. Thailand, Malaysia and Indonesia*
L. Northern Australia*
M. The Philippine Islands*
N. The South China Sea
O. The South Pacific Islands*
P. The Hawaiian Archipelago
(* Obtained from positive records based on specimens in the British Museum)
Of these, all but F, G and P are areas in which O. superba an occur.
|
|
Figure 13 |
|
|
|
Evolution and Systematics | |
The taxonomic basis for the paleontology of class Ophiuroidea was built in the 1960s through the evaluation of the skeletal elements of a different species (Stöhr, O'Hara and Thuy 2012). This includes the plates, papillae, spines, teeth and shields (Stöhr, O'Hara and Thuy 2012). This increased identification rates of the species as it allowed for the complete assemblages of each species as soon as discovery occurred (Stöhr, O'Hara and Thuy 2012).
As previously stated, O. superba was first described in 1915 by Clark, this was a very minimal description of a single specimen’s colouration and disk size. He depicted a uniform colouration in its’ exterior with no dark markings, this however is contradictory to later observations made of the species which shoe distinct black or purple coloured bands (Stöhr, O’Hara & Thuy 2015). An assumption can be made that the initial specimens’ colouration, which was acquired from the Colombian Museum in 1914, was not preserved properly and appeared as a solid colour (Clark 1915).
Phylum – Echinodermata
Subphylum – Asterozea
Class – Ophiuroidea
Order – Ophiurida
Family – Ophiolepididae
Genus – Ophiolepis
Species – Superba
(Stöhr, O’Hara & Thuy 2015)
|
|
|
Conservation and Threats | |
Opiuroidea as a whole are not threatened directly by fishing activities as they are not a target of the marine fisheries, apart from smaller collection efforts as research specimens and private aquarium pets. They are not a desirable food sources due to their strong exoskeletons, strong spines and minimal size. In comparison its sister class Echinoidea (sea urchin) is a group actively harvested for consumption by humans. Although not effected directly by marine fisheries there are some potential indirect effects which may result from damages to the coastal sea beds as a result of dredging and more.
A potential major threat to O. Superba, like many other slow moving benthic animals, is the effects of climate change. With increasing temperature the environment this species is found in is at high risk of degradation from coral bleaching. Drastically changing the health of its environment and subsequently influencing its overall ecological niche.
|
|
|
References | |
Astley, HC 2012. ‘Getting around when you’re round: quantitative analysis of the locomotion of the blunt-spines brittle star, Ophiocoma echinata’, Journal of Experimental Biology, vol. 215, pp. 1923-1929.
Clark, H.L. 1915. 'The Echinoderms of Ceylon other than Holothurians', Spolia Zeylandica, vol. 10, no. 37, pp. 83-102.
Clark, AM & Rowe, FWE 1971. Monograph of Shallow-water Indo-West Pacific Echinoderms, Trustees of the British Museum (Natural History), London.
Cole, N 2007, Sea Stars: Echinoderms of the Asia/Indo-Pacific, Neville Coleman’s Underwater Geographic, Springwood, Queensland.
Hendler, G, Miller, JE, Pawson, DL & Kier, PM 1995, Sea Stars, Sea Urchins, and Allies: echinoderms of Florida and the Caribbean, Smithsonian Institution Press, Washington.
Lawrence, L 1987, A functional Biology of Echinoderms, The Johns Hopkins University Press, Baltimore.
Romanes, GJ 1885, Jelly-fish, Star-fish and Sea-urchins: Being a research on Primitive Nervous system, D. Appleton and Company, New York.
Rowe, FEW & Gates, J 1995, Zoological Catalogue of Australia: Echinodermata, vol. 33, CSIRO Australia, Melbourne.
Ruppert, E, Fox, R and Barnes, R 2004. Invertebrate Zoology. 7th edn, Thomson-Brooks/Cole, California.
Clark, HL 1915. ‘The Echinoderms of Ceylon other than Holothurians’, Spolia Zeylandica, vol. 10, no. 37, pp. 83-102.
Stöhr, S, O'Hara, T and Thuy, B 2012. ‘Global Diversity of Brittle Stars (Echinodermata: Ophiuroidea)’, PLoS ONE, vol. 7, no. 3, e31940.
Stöhr, S, O’Hara, T & Thuy, B 2015, Ophiuroidea database - Ophiuroidea taxon details, viewed 11th of May 2016, VLIZ, <http://www.marinespecies.org/ophiuroidea/aphia.php?p=taxdetails&id=213464>
|
|
|
|
|