- Biogeographic Regions
- indian ocean
- atlantic ocean
- pacific ocean
- mediterranean sea
- Other Geographic Terms
Tedania ignis; an inhabited algae species is Sargassum cymosum. (Boffi, 1972; Chao and Tsai, 1995; Hendler, et al., 1995; McGovern, 2002a; McGovern, 2002b; McKeton and Wood, 2006; Mladenov and Emson, 1988; Smithsonian Marine Station at Fort Pierce, 2010)is benthic and resides inshore, on continental shelves, and continental slopes. This brittle star shelters itself in various subtropical marine and tropical marine habitats, including rubble, algae, corals, sponges, reefs, mangrove areas, ship hulls, and sea grasses like turtle grass. is more frequent on sponges than algae. This species can inhabit sponges in densities up to 1,892 individuals per 100 grams of dried sponge; 3,000 individuals per liter have also been reported. The density of depends on space and food available. One species of sponge inhabited by this brittle star is
- Range depth
- 1 to 518 m
- 3.28 to 1699.48 ft
- Average depth
- 259 m
- 849.74 ft
Sexual reproduction results in planktonic ophiopluteus larvae that have bilateral symmetry. They are v-shaped and have a crystalline skeleton with curving ciliated bands for feeding. Ophiopluteus larvae are free swimming until they metamorphose into adults. (Hendler, et al., 1995; Schoener, 1972)
- Sexual Dimorphism
- sexes alike
- Development - Life Cycle
- Mating System
- polygynandrous (promiscuous)
- Key Reproductive Features
- year-round breeding
- broadcast (group) spawning
- Breeding interval
- Asexual and sexual year round, but sexual more frequent late summer to fall.
- Parental Investment
- no parental involvement
This brittle star forms colonies made of asexually produced clones, and the occasional sexually acquired recruit. Information on the locomotion specifically of (Majer, et al., 2009; McGovern, 2002a; McKeton and Wood, 2006; Mladenov and Emson, 1988)was not found. Other ophiuroids move by pulling themselves along with their flexible arms. They move in any direction across the substrate and do not favor a particular arm. An interesting discrepancy in damage-release reaction time exists between populations of this species on algae and sponges. The populations studied were close to each other. During sexual reproduction gametes from different colonies presumably mix. The expected result from this interbreeding is a similar response signal across all colonies, but this is not supported by the data. This has led to the hypothesis that may be exhibiting learned behavior. More research is needed to support this claim.
Communication and Perception
- Communication Channels
- Other Communication Modes
foraminiferans, bryozoans, organic detritus, and small gastropods. This brittle star is a suspension feeder using its tube feet to catch small particles and moving them toward its mouth. is also characterized as a deposit feeder, cleaning the outer surface of its habitat and filtering food from the water. A large individual suspension feeds by raising its arms into the water column. will also situate itself at the base of the excurrent pore of a sponge to collect food particles. (Hendler, et al., 1995; McKeton and Wood, 2006)is detritophagous, i.e., it feeds mainly on small particles of detritus. The stomach typically contains
- Primary Diet
- eats non-insect arthropods
- eats other marine invertebrates
- Animal Foods
- aquatic crustaceans
- other marine invertebrates
- Plant Foods
- Other Foods
- Foraging Behavior
A defense mechanism of O. savignyi is its use of autonomy (casting off of limbs) when escaping predators. It also is capable of regenerating them. Negative phototaxis and damage-release alarm signals are also evolved characteristics to escape predators. A fish may bite the brittle star into smaller pieces before consuming it, so the ability to lose and regenerate limbs is an advantage. This species is prey to crabs and shrimp. (Hendler, et al., 1995; McKeton and Wood, 2006)
dominates sponge habitats and competes with other brittle stars for space. In the Caribbean it inhabits at least ten species of sponges. This brittle star also inhabits various algae. Numbers are greater in sponges than in algal turf, probably because sponges provide a better refuge against predators. Other than providing food for species of fish, shrimp, and crab, the species at times occludes the excurrent siphon of sponges, which is potentially harmful. acts as a detritivore and recycles dead plankton, bacteria, small crustaceans, and invertebrates.
Algae that Hypnea species. Sponges that inhabit include Haliclona species, Tedania ignis, Scopalina ruetzleri, and Amphimedon viridis. (Boffi, 1972; Chao and Tsai, 1995; Hendler, et al., 1995; McGovern, 2002b; Mladenov and Emson, 1988)inhabit include
- Ecosystem Impact
Economic Importance for Humans: Positive
Ophiactis savignyi has no significant positive impact on humans. (; McKeton and Wood, 2006)
Economic Importance for Humans: Negative
Jason Haas (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects.
- Atlantic Ocean
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
- Pacific Ocean
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
helps break down and decompose dead plants and/or animals
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
an animal that mainly eats decomposed plants and/or animals
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- external fertilization
fertilization takes place outside the female's body
union of egg and spermatozoan
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
found in the oriental region of the world. In other words, India and southeast Asia.
chemicals released into air or water that are detected by and responded to by other animals of the same species
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- radial symmetry
a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).
structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
- saltwater or marine
mainly lives in oceans, seas, or other bodies of salt water.
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
- year-round breeding
breeding takes place throughout the year
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
Boffi, E. 1972. Ecological aspects of ophiuroids from the phytal of S. W. Atlantic Ocean warm waters. Marine Biology, 15: 316-328.
Chao, S., C. Tsai. 1995. Reproduction and population dynamics of the fissiparous brittle star Ophiactis savignyi (Echinodermata: Ophiuroidea. Marine Biology, 124: 77-83.
Hendler, G., J. Miller, D. Pawson, P. Kier. 1995. Sea Stars, Sea Urchins, and Allies Echinoderms of Florida and the Caribbean. Washington and London: Smithsonian Institution Press.
Majer, A., J. Trigo, L. Duarte. 2009. Evidence of an alarm signal in Ophiuroidea (Echinodermata). Marine Biodiversity Records, 2: e102.
McGovern, T. 2002. Patterns of sexual and asexual reproduction in the brittle star Ophiactis savignyi in the Florida Keys. Marine Ecology Progress Series, 230: 119-126.
McGovern, T. 2002. Sex-ratio bias and clonal reproduction in the brittlestar Ophiactis savignyi. Evolution, 56 (3): 511-517.
McKeton, K., J. Wood. 2006. "Marine Invertebrates of Bermuda" (On-line). Little brittle star (Ophiactis savignyi). Accessed April 27, 2011 at http://www.thecephalopodpage.org/MarineInvertebrateZoology/Ophiactissavignyi.html.
Mladenov, P., R. Emson. 1988. Density, size structure and reproductive characteristics of fissiparous brittle stars in algae and sponges: evidence for interpopulational variation in levels of sexual and asexual reproduction. Marine Ecology Progress Series, 42: 181-194.
Morgado, E., M. Tanaka. 2001. The macrofauna associated with the bryozoan Schizoporella errata (Walters) in southeastern Brazil. Scientia Marina, 65 (3): 173-181.
Roy, M., R. Sponer. 2002. Evidence of a human-mediated invasion of the tropical western Atlantic by the ‘world’s most common brittlestar’. Proceedings of the Royal Society - Biological Sciences, 269: 1017-1023. Accessed April 23, 2011 at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1690993/.
Roy, M., R. Sponer. 2001. The recent evolutionary history of Ophiactis savignyi (Echinodermata; Ophiuroidea). Pp. 307-311 in M Barker, ed. Echinoderms 2000: proceedings of the 10th international conference, Dunedin, Vol. 1st edition. Netherlands: Aa Balkema. Accessed April 23, 2011 at http://books.google.com/books?id=NEog_WHJ5HcC&pg=PA307&lpg=PA307&dq=Ophiactis+savignyi&source=bl&ots=QMXwQgcU4X&sig=PMPeVAuf6Ew17GClRIZ-_CL78gk&hl=en&ei=K7t5S437JI2KnQe9l_GnCQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBAQ6AEwAzgK#v=onepage&q=&f=false.
Schoener, A. 1972. Fecundity and possible mode of development of some deep-sea ophiuroids. Limnology and Oceanography, 17 (2): 193-199.
Smithsonian Marine Station at Fort Pierce, 2010. "Field Guide to the Indian River Lagoon, Florida Savigny's Brittle Star Ophiactis savignyi" (On-line). Smithsonian Marine Station at Fort Pierce. Accessed May 02, 2011 at http://www.sms.si.edu/IRLFieldGuide/Ophiac_savign.htm.
Stohr, S., H. Hansson. 2009. "Ophiactis savignyi (Müller & Troschel, 1842)" (On-line). World Register of Marine Species. Accessed April 23, 2011 at http://www.marinespecies.eu/aphia.php?p=taxdetails&id=125122.