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The brittlestar Ophiophragmus filograneus. Photo courtesy D. Pawson, National Museum of Natural History. Photographer J. Miller.

Species Name: Ophiophragmus filograneus Lyman, 1875
Common Name: None
Synonymy: Ophiophragmus filograneus Lyman, 1875
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Echinodermata Ophiuroidea Ophiurida Amphiuridae Ophiophragmus

    Species Description

    Ophiophragmus filograneus is an amphiurid estuarine brittlestar. The arm color is mostly dark with occasional light bands, and the disk color is usually gray or brown. There are two podial scales per podial pore set at right angles and separated from one another by a distinct gap. The aboral arm plates are not split in half. The disk scales are often darker than the base color of the disk, typically with lighter borders, and the disk margin has 20 or more fence papillae between the arms. The arm spines nearest the disk are significantly longer than those at the ends of the arms. (Pomory 2007, SMS undated).

    Potentially Misidentified Species

    Although echinoderm taxonomy is a highly specialized science, the general appearance (see above), along with collection information (e.g., location and habitat) should allow unambiguous identification of Ophiophragmus filograneus. The congeneric species Ophiophragmus wurdemani occurs in Florida waters, but is restricted to unvegetated benthic habitats in more saline waters and does not penetrate deeply into Florida's brackish estuaries (Turner and Meyer 1980).

  2. HABITAT AND DISTRIBUTION

    Regional Occurrence

    Ophiophragmus filograneus has been reported only from brackish waters of Florida. (Talbot and Lawrence 2002, Pomory 2007).

    IRL Distribution

    Ophiophragmus filograneus is common throughout the IRL in association with Halodule wrightii seagrass beds (Thompson 1978). The Mosquito Lagoon portion of the IRL system is reported as the northern distributional limit for the species (Turner and Meyer 1980).

  3. LIFE HISTORY AND POPULATION BIOLOGY

    Age, Size, Lifespan

    The central disc of Ophiophragmus filograneus typically grows to as much as 9-10 mm in diameter, and the long arms attain a length of up to 150 mm (Hendler et al. 1995, Talbot and Lawrence 2002).

    Abundance

    Clements et al. (1994) sampled natural and planted Tampa Bay Halodule beaudettei beds on a quarterly basis to determine Ophiophragmus filograneus population densities. Mean quarterly densities averaged 10.6 individuals per square meter in natural grass beds (ranging from 0-32 individuals per square meter) and 33.8 individuals per square meter in planted beds (ranging from 0-48.6 individuals per square meter).

    Grizzle (1984) lists O. filograneus as among the most common macrobenthic species at two IRL sites, one of which the authors considered to be more environmentally degraded than the other. Brittlestar abundance was approximately 4 times higher at the undegraded site, and the author considers O. filograneus to be an equilibrium species rather than an opportunistic species.

    Reproduction

    Several authors (e.g., Stancyk 1974, Turner 1974, Turner and Meyer 1980) indicate that Ophiophragmus filograneus forms dense reproductive populations in the Florida Halodule beds in which it occurs beds.

    Embryology

    Stancyk (1973) hypothesized that Ophiophragmus filograneus exhibits direct development (no planktonic phase), base on egg type. The author suggests direct development as an adaptation for life in a harsh environment, as has been suggested for other direct-developing echinoderms

    Turner (1974) examined the post-metamorphic arm growth of Tampa Bay O. filograneus and revealed the typical pattern to involve a faster rate of growth in two non-adjacent arms and a concurrent slower growth in the remaining arms. The author suggests this pattern may be an adaptation allowing earlier descent of the disc within the substratum and away from predation and salinity and temperature fluctuations, with the two arms displaying concentrated growth remaining long enough to reach up to the sediment surface. Arm lengths are gradually equalized as individuals grow.

  4. PHYSICAL TOLERANCES

    Temperature

    Restricted to Florida, this is an exclusively subtropical species. Individuals appear to actively burrow deeper within the soft sediment in response to adverse surface conditions, including cold temperature (Stancyk 1970).

    Salinity

    Although echinoderms are often cited as the only strictly marine major animal phylum, a number of representatives may be encountered at salinities less than full-strength seawater (Stickle and Diehl 1987). Of the approximately 40 echinoderm species reported from brackish waters, Ophiophragmus filograneus is the species with the greatest tolerance for hyposaline conditions, occurring in estuaries but not in the open sea (Turner and Meyer 1980, Talbot and Lawrence 2002). This species appears to be the only echinoderm restricted to estuarine habitats.

    Talbot and Lawrence (2002) questioned whether exclusion of O. filograneus from higher open ocean salinities was due to physiological adaptation for reduced salinities or to some other factor. Laboratory experiments revealed that O. filograneus collected from Tampa Bay at 22 ppt was more physiologically stressed (based on measurements of respiration, metabolism, and limb regeneration rate) at 16 ppt than at either 22 ppt or 30 ppt. The findings suggest exclusion from the open ocean may be due to factors other than salinity tolerance, such as dietary resource availability, sediment type, or exclusion due to competition or predation.

  5. COMMUNITY ECOLOGY

    Trophic Mode

    Ophiophragmus filograneus typically buries its disc in muddy sand and extends one or more of its arms up to the sediment to feed (Stancyk 1974). As with a number of infaunal brittlestars,O. filograneus is capable of functioning as both a suspension-feeder and as a deposit-feeder likely to routinely ingest significant quantities of detrital material (Clements et al 1994).

    As with some other brittlestars, O. filograneus also appears capable of resorbing portions of its own biomass if environment conditions (e.g., starvation) force individuals to catabolize tissue for maintenance (Dobson et al., 1991). Turner and Murdoch (1976) describe a pattern of preferential tissue resorption in which tissues from the disc, oral frame, and arm tips are catabolized before other body tissues, leaving the majority of arm tissue intact to take advantage of favorable feeding conditions should they occur.

    Competitors

    The exclusively estuarine distribution of this species likely minimizes competitive interactions with other brittlestar species.

    Predators

    Ophiophragmus filograneus is an important component in the diet of a number of benthic-feeding animals, most notably stingrays of genus Dasyatis and the cownose ray Rhinoptera bonasus (Turner at al. 1982).

    The need for individuals to keep portions of their arms exposed at the sediment surface for feeding purposes also exposes brittlestars species to a high degree of sublethal partial predation, and animals often lose portions of their exposed arms to shrimps, crabs, flatfish and other epibenthic predators (Duineveld and Van Noort 1986, O'Connor et al. 1986). Based on a Tampa Bay study, however Clements et al. (1994) indicated that partial predation on seagrass-associated O. filograneus appears low compared to rates reported for other infaunal brittlestars, particularly those from unvegetated habitats.

    Habitats

    Ophiophragmus filograneus is a common inhabitant of estuarine Florida subtidal unconsolidated substratum environments and seagrass meadows, particularly Halodule wrightii beds (Clements et al. 1994, Rose 1997, Pomory 2007).

    O. filograneus is capable of regenerating lost arms from autotomized discs.. The high incidence of O. filograneus regenerating arms in the field suggests a high degree of sub-lethal predation in habitats occupied by this species (Stancyk 1974, Lawrence 1990, Rose 1997). Clements et al. (1994) estimate that 52-94% of brittlestars collected from natural and planted Tampa Bay H. beaudettei beds showed evidence of arm regeneration. Brown (1982) also reported a degree of gut replacement in O. filograneus during regeneration of portions of autotomized discs.

    Activity Time

    Neanthes succinea is an active forager primarily at night, spending most of the day in a mucous-lined tube (Craig et al. 2003).

  6. ADDITIONAL INFORMATION

    No information is available at this time

  7. REFERENCES

    Brown BK. 1982. Gut replacement during disc regeneration of the autotomized disc of Ophiophrugmus filograneus (Echinodermata: Ophiuroidea). Unpublished master's thesis, Florida Institute of Technology, Melbourne. 90 p.

    Clements LAJ, Bell SS, and JR Kurdziel. 1994. Abundance and arm loss of the infaunal brittlestar Ophiophragmus filograneus (Echinodermata: Ophiuroidea), with an experimental determination of regeneration rates in natural and planted seagrass beds. Marine Biology 121:97-104.

    Dobson WE, Stancyk SE, Clements LA, and RM Showman. 1991. Nutrient translocation during early disc regeneration in the brittlestar Microphiopholis gracillima (Stimpson) (Echinodermata: Ophiuroidea). Biological Bulletin 180:167-184.

    Duinevetd GCA, and GJ Van Noort. 1986. Observations on the population dynamics of Amphiura filiformis (Ophiuroidea: Echinodermata) in the southern North Sea and its exploitation by the dab Limanda. Netherlands Journal of Sea Research 20:85-94.

    Grizzle RE. 1984. Pollution indicator species of macrobenthos in a coastal lagoon. Marine Ecology Progress Series 18: 191-200.

    Hendler GJ, Miller E, Pawson DL, and PM Kier. 1995. Sea stars, sea urchins, and allies. Echinoderms of Florida and the Caribbean. Washington, D.C.: Smithsonian Institution Press.

    Lawrence JM. 1990. The effect of stress and disturbance on echinoderms. Zoological Science 7:17-28.

    O'Connor B, Bowmer T, McGrath D, and R Paine. 1986 Energy flow through an Amphiura filiformis (Ophiuroidea: Echinodermata) pepulation in Galway Bay, west coast of Ireland: Preliminary investigation. Ophelia 26:351-357.

    Pomory CM. 2007. Key to the common shallow-water brittle stars (Echinodermata: Ophiuroidea) of the Gulf of Mexico and Caribbean Sea, Caribbean Journal of Science Special Publication No. 10. University of Puerto Rico, Mayaguez. 42 p.

    Rose CS. 1997. Distribution, body size, and regeneration of the amphiurid, Ophiophragmus filograneus in the Tampa Bay area, with special reference to the presence of the seagrass, Halodule wrightii. MS thesis. University of South Florida, Tampa.

    Stancyk SE. 1970. Studies on the biology and ecology of ophiuroids at Cedar Key, Florida. M.Sc. Thesis. University of Florida. 92 p.

    Stancyk SE. 1973. Development of Ophiolepis elegans (Echinodermata: Ophiuroidea) and its implications in the estuarine environment. Marine Biology 21:7-12.

    Stancyk SE. 1974. Life history patterns of three estuarine brittlestars (Ophiuroidea) at Cedar Key, Florida. PhD dissertation. University of Florida, Gainesville.

    Stickle WB, and WJ Diehl. 1987. Effects of salinity on echinoderms. Echinoderm Studies 2:235-285.

    Talbot TD and JM Lawrence. 2002. The effect of salinity on respiration, excretion, regeneration and production in Ophiophragmus filograneus (Echinodermata: Ophiuroidea). Journal of Experimental Marine Biology and Ecology 275:1-14.

    Thomas LP. 1961. Distribution and salinity tolerance in the amphiurid brittlestar Ophiophragmus filograneus (Lyman, 1875). Bulletin of Marine Science of the Gulf Caribbean 11:158-160.

    Turner RL. 1974. Post-metamorphic growth of the arms in Ophiophragmus filograneus (Echinodermata: Ophiuroidea) from Tampa Bay, Florida (USA). Marine Biology 24:273--277.

    Turner RL and CE Meyer. 1980. Salinity tolerance of the brackish-water echinoderm Ophiophragmus filograneus (Ophiuroidea). Marine Ecology Progress Series 2:249-256.

    Turner RL, Heatwole DW, and SE Stancyk. 1982. Ophiuroid discs in stingray stomachs: evasive autotomy or partial consumption of prey? p. 331-335 In: Lawrence, J. M. (ed.) Echinoderms. Proceedings of the International Conference, Tampa Bay. A. A. Balkema, Rotterdam.

Report by: J. Masterson, Smithsonian Marine Station
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Page last updated: October 1, 2008

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