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The rock-boring urchin, Echinometra lucunter. Photo by LH Sweat, Smithsonian Institution.

Two Echinometra lucunter feeding on the floating alga, Sargassum. Photo by LH Sweat, Smithsonian Institution.

Species Name: Echinometra lucunter Linnaeus, 1758
Common Name: Rock Boring Urchin
Synonymy: Echinus lucunter Linnaeus, 1758

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Echinodermata Echinoidea Echinoida Echinometridae Echinometra

    Please refer to the accompanying glossary for definitions of the descriptive terms used in this report.

    Species Description

    The rock boring urchin, Echinometra lucunter, has an elongate oval test with two rows of large tubercles along the ambulacra and interambulacra, pairs of pores arranged in arcs of six, and a large peristome (Hendler et al. 1995). The spines are long and slender, thickened at the base, and sharply pointed at the tips.

    On the aboral side, the primary and secondary spines are dark olive green, with greenish violet to purple tips (Hendler et al. 1995). The general color of the spines is blackish, although some specimens may exhibit a reddish color. Test and muscle bases of the spines are shades of red-brown. Tube feet on the aboral surface are light brown, and the terminal disks are dark brown to blackish. Oral spines have a lighter color than aboral ones, light olive green with a violet gradient near the tips. The test and peristome are flecked with creamy brown. The tube feet near the mouth are translucent, with terminal disks that are creamy white in color, lined with a narrow dark brown band, and measuring about twice the size of those on the aboral feet.

    As with many intertidal organisms, studies have revealed differences in the structure of E. lucunter from environments with varying wave action. Specimens from high-energy areas tend to have tests that are flatter, thicker, smaller, and narrower, and a distinctive pattern of insertion of ocular plates in the apical system (Lewis & Storey 1984).

    Potentially Misidentified Species

    The general shape and size of E. lucunter is similar to that of the reef urchin, E. viridis. However, the latter usually has a more circular test shape and longer spines, a reddish test, pore pairs in arcs of five instead of six, and conspicuously white milled rings around the base of each spine (Hendler et al. 1995).


    Habitat & Regional Occurence

    The rock-boring urchin is commonly found on limestone reef rock in the surf zone (Hendler et al. 1995). It can be very common in shallow, exposed fore reef or reef crest habitats, occupying shallow depressions or borrows created by the abrading action of the urchin’s spines and teeth on the rock surface. The success of E. lucunter in harsh environments may be partially due to its apparent resistance to stresses caused by increased temperature and salinity (Hendler 1977).

    The range of E. lucunter extends from Beaufort, North Carolina and Bermuda southward throughout the Caribbean and eastern Central America to Desterra, Brazil. Populations can also be found in West Africa. The subspecies E. lucunter polypora Pawson, is common at Ascension and St. Helena Islands (Pawson 1978). The depth range for this species is generally zero to 45 meters (Serafy 1979).

    Indian River Lagoon Distribution

    The distribution of E. lucunter within the IRL remains undocumented. However, this species appears to be concentrated mostly around rock jetties and other hard structures near inlets (LH Sweat, personal observation).



    E. lucunter reaches a maximum size of 15 cm, though most individuals are about half that size (Hendler et al. 1995).


    The abundance of E. lucunter in the IRL is undocumented. However, studies have reported densities elsewhere of up to 129 individuals per square meter (Greenstein 1993).

    Reproduction & Embryology

    The annual spawning cycle for the rock-boring urchin has been reported to occur in late summer in the Florida Keys (McPherson 1969), peaks in the fall in Puerto Rico (Cameron 1986), and occurs variably throughout the year in Panama (Lessios 1981). Lewis & Storey (1984) documented one spawning event per year in urchins from high-energy environments, and two events annually in urchins from low-energy areas. Tennent et al. (1931) reported that spawning in one individual takes about 15 minutes. Fertilization and development are adversely affected by reducing salinity (Petersen & Almeida 1976). Larvae of this species have been reared through metamorphosis in the laboratory (e.g. Mortensen 1921).


    No information is available at this time


    Trophic Mode

    The rock-boring urchin feeds mostly at night from their burrows, consuming clumps of drift algae, or venturing out of the burrow to feed and then usually returning to the same hole (McPherson 1969, Abbott et al. 1974, Ogden 1976). In Panama, individuals were observed to clear the area around their burrows of all organisms except calcareous algae (Hendler et al. 1995).

    Movement & Behavior

    Antagonistic behaviors among conspecifics have been observed for this urchin. Grunbaum et al. (1978) found that intruding urchins were pushed and bit by the individual originally inhabiting the burrow, and the inhabitant won most altercations. Escape responses have been observed in individuals following exposure to chemical extracts from other Echinometra spp. (Parker & Shulman 1986).


    Predators of E. lucunter include: ruddy turnstones, Arenaria interpres; conchs; and fish including triggerfish, grunts, jacks and wrasses (Abbott et al. 1974). Predation by the reticulate cowrie-helmet, Cypraecassis testiculus, has also been documented for individuals in Panama (Hendler 1977).

    PARASITES & Associated Species:

    The eulimid gastropod, Monogamus minibulla is a parasite of the rock-boring urchin (Warén & Moolenbeek 1989). The turbellarian, Syndisyrinx collongistyla, has been reported to infest the intestines of E. lucunter in Jamaica, S. evelinae has been found in specimens from St. Barthélemy (Hertel et al. 1990). Protozoans have also been reported to infest E. lucunter (Mortensen 1943).  The rock-boring urchin has been observed to share its burrow with several associates, including a goby, a porcelain crab, and a brittle star (Schoppe 1991).


    Ecological Significance

    The burrowing behavior of E. lucunter can contribute greatly to the breakdown of coral reefs and intertidal limestone shorelines, especially when urchin population densities are high.  Hoskin & Reed (1985) estimated that burrows are excavated in approximately 3 years. Rates of erosion on coral reefs due to this excavation have been reported at 3.9 kg per square meter annually in the Virgin Islands, 7.0 kg per square meter annually in Bermuda, and 24 g per urchin per year in Barbados (Ogden 1977).

    Ablanedo et al. (1990) found that individuals of E. lucunter accumulate certain heavy metals in the gonads, test, spines, and lantern. Therefore, they can be used as an indicator species to reflect the level of environmental pollution to which they are exposed.


    Abbott DP, Ogden JC & IA Abbott. 1974. Studies on the Activity Pattern, Behavior, and Food of the Echinoid Echinometra lucunter (Linnaeus) on Beachrock and Algal Reefs in St. Croix, U.S. Virgin Islands. West Indies Laboratory Special Publication No. 4. Fairleigh Dickinson University. Christiansted, St. Croix. U.S. Virgin Islands. iv + 111 pp.

    Ablanedo N, Gonzalez H, Ramirez M & I Torres. 1990. Evaluación del erizo de mar Echinometra lucunter como indictor de contaminación por metales pesados, Cuba. Aquat. Living Res. 3: 113-120.

    Cameron RA. 1986. Reproduction, larval occurrence and recruitment in Caribbean sea urchins. Bull. Mar. Sci. 39: 332-346.

    Greenstein BJ. 1993. Is the fossil record of regular echinoids really so poor? A comparison of living and subfossil assemblages. Palaios 8:587-601.

    Grunbaum H, Bergman G, Abbott DP & JC Ogden. 1978. Intraspecific agonistic behavior in the rock-boring sea urchin Echinometra lucunter (L.) (Echinodermata: Echinoidea). Bull. Mar. Sci. 28: 181-188.

    Hendler G. 1977. The differential effects of season stress and predation on the stability of reef-flat echinoid populations. In: Taylor DL (Ed.). 217-223. Proceedings: Third International Coral Reef Symposium. Volume 1 (Biology). Rosenstiel School of Marine & Atmospheric Science, University of Miami. Miami, Florida.

    Hendler G, Miller JE, Pawson DL & PM Kier. 1995. Sea stars, sea urchins, and allies: echinoderms of Florida and the Caribbean. Smithsonian Institution Press. Washington, D.C. 390 pp.

    Hertel L, Duszynski DW & JE Ubelaker. 1990. Turbellarians (Umagillidae) from Caribbean urchins with a description of Syndisyrinx collongistyla, n. sp. Trans. Amer. Microscop. Soc. 109: 272-281.

    Hoskin CM & JK Reed. 1985. Carbonate sediment production by the rock-boring urchin Echinometra lucunter and associated endolithic infauna at Black Rock, Little Bahama Bank. Symposia Ser. Underwater Res. 3: 151-161.

    Lessios HA. 1981. Reproductive periodicity of the echinoids Diadema and Echinometra on the two coasts of Panama. J. Exp. Mar. Biol. Ecol. 50: 47-61.

    Lewis JB & GS Storey. 1984. Differences in morphology and life history traits of the echinoid Echinometra lucunter from different habitats. Mar. Ecol. Prog. Ser. 15: 207-211.

    McPherson BF. 1969. Studies on the biology of the tropical sea urchins Echinometra lucunter and Echinometra viridis. Bull. Mar. Sci. 19: 194-213.

    Mortensen T. 1921. Studies of the development and larval forms of echinoderms. G.E.C. Gad. Copenhagen, Denmark. xxxiii + 266 pp.

    Mortensen T. 1943. A Monograph of the Echinoidea. Volume III. (3). Camarodonta. I. Orthopsidae, Glyphocyphidae, Temnopleuridae and Toxopneustidae. CA Reitzel, Copenhagen. vii + 553 pp. 56 pls.

    Ogden JC. 1976. Some aspects of herbivore-plant relationships on Caribbean reefs and seagrass beds. Aquat. Botany 2: 103-116.

    Ogden JC. 1977. Carbonate-sediment production by parrotfish and sea urchins on Caribbean reefs. Stud. Geol. 4: 281-288.

    Parker DA & MJ Schulman. 1986. Avoiding predation: Alarm responses of Caribbean sea urchins to simulated predation on conspecific and heterospecific sea urchins. Mar. Biol. (Berlin) 93: 201-208.

    Pawson DL. 1978. The echinoderm fauna of Ascension Island, South Atlantic Ocean. Smithsonian Contrib. Mar. Sci. 2. iv + 31 pp.

    Petersen JA & AM Almeida. 1976. Effects of salinity and temperature on the development and survival of the echinoids Arbacia, Echinometra and Lythechinus. Thalassia Jugoslavia 12: 297-298.

    Schoppe S. 1991. Echinometra lucunter (Linnaeus) (Echinoidea, Echinometridae) als Wirt einer komplexen Lebensgemeinschaft im Karibischen Meer. Helgoländ. Meeresunt. 45: 373-379.

    Serafy DK. 1979. Echinoids (Echinodermata: Echinoidea). Memoirs of the Hourglass Cruises 5: 1-120.

    Tennent DH, Gardiner MS & DE Smith. 1931. A cytological and biochemical study of the ovaries of the sea urchin Echinometra lucunter.Carnegie Institution of Washington Publication No. 27. 1-46. pls. 1-7.

    Warén A & R Moolenbeek. 1989. A new eulimid gastropod, Trochostilifer eucidaricola, parasitic on the pencil urchin Eucidaris tribuloides from the southern Caribbean. Proc. Biol. Soc. Wash. 102: 169-175.

Page by LH Sweat
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Page last updated: 31 October 2012

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