Echinometra lucunter

Geographic Range

Rock-boring urchins are distributed throughout the Caribbean and coastal South Atlantic subtropical region, from Bermuda through southern Florida and the islands of the Caribbean (particularly Barbados) to Desterra, Brazil.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native
• atlantic ocean atlantic ocean
  • native native

Habitat

This urchin is typically found in shallow waters of 0-2 meters and has been reported at depths up to 45 meters. It is most abundant on tidal terraces and rocky shores in areas of high energy waves and on shallow coral reefs within rock crevices, and may be present (though less commonly found) on sandy bottoms.

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• reef reef
• coastal coastal

• Other Habitat Features
• intertidal or littoral intertidal or littoral

Physical Description

This species has an elliptical shape with 100 to 150 colored spines on the arboral surface. Size at maturity is typically 40 mm in diameter or smaller, although some individuals recorded larger than 150 mm have been recorded. Test color is variable between individuals, ranging between a black, brown, green or dark blue color with lighter colors on the arboral surface. In some cases the apical system of the test is bright red, with black spines. This species is differentiated from other closely related species by having fewer pore-pairs per arc, fewer ambulacral and interambulacral plates, a different apical system, and slender, tridentate pedicellariae. Like all other echinoids, it has 5 teeth located within a specialized feeding apparatus known as Aristotle's lantern. As with many urchins, this species' spines are venomous.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• radial symmetry radial symmetry
• venomous venomous

• Sexual Dimorphism
• sexes alike

Development

Post-fertilization, zygotes undergo first cleavage after approximately 90 minutes. Planktonic larvae develop in several stages, including the blastula (reached at the 128 cell stage), gastrula (1000 cell stage), and prism stages. The following stage, four-armed pluteus, is reached after the second day of fertilization. Following the fourth day, posterodorsal arms appear and full metamorphosis occurs approximately 19 days after fertilization. This urchin is a slow-growing and relatively long-lived echinoid species with a life expectancy over 10 years.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

This species is usually found in dense aggregations. Spawning occurs once or twice (depending on individual conditions) in the summer. Individuals release their gametes into the water column, with males usually spawning before females. This may act as a cue, stimulating females to release eggs.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Sexual maturity occurs when individuals reach a test diameter of at least 20 mm and when ripe sex cells are present in the gonads. Gonad development occurs most often during spring, with spawning occuring in the summer, usually once but in some cases twice per year. The gonadal index (number of sex cells/unit of gonad tissue) is highest during summer. The gametogenic cycle comprises 5 different stages: proliferative, premature, mature, depleted, and resting. Release of the male’s spermatozoa elicits release of oocytes by females. Spawning may also occur during other times of the year outside of summer, depending primarily on hydrodynamics and nutrient availability. There is currently no published information noting the average number of offspring, gestation period, and birth mass for this species.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• broadcast (group) spawning

This species exhibits no parental investment after gamete release. Zygotes become planktonic larvae and drift unattended until they develop into the benthic adult form.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Rock-boring urchins exhibit a slow growth rate. After completing their first year of life, average life expectancy is over 10 years. However, there have been no detailed studies documenting the average lifespan in the wild, and estimated lifespans in captive individuals are unknown.

Behavior

This species uses its tube feet to attach itself to rocky surfaces and it has the ability to create its own burrows. Most movements occur during dark hours, when urchins move out of crevices and rock burrows to feed, primarily on algae, and then return to them for shelter. This species also exhibits territorial and agonistic behaviors to defend its shelter and access to food from conspecifics. However, it can coexist with congeners such as Echinometra viridis without competing for food or resources.

• Key Behaviors
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial
• social social

Home Range

This species may occur in population densities of up to 240 individuals per 2.6 km^2. Individuals have been documented to travel between 0 and 3 cm^2 over a period of four days.

Communication and Perception

These urchins communicate with conspecifics through tactile means, using their tube feet and spines and, when spawning, through chemical signals. It is also able to detect shadows and chemicals released by its predators. Although they have no discrete visual organs, urchins have been found to express vision related genes in their tube feet. It has also been found that their spines filter light from wide angles, allowing them to detect relatively fine visual detail (species with densely packed spines have greater acuity than those with widely spaced spines).

• Communication Channels
• tactile tactile
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

This urchin is an omnivorous species, using its arboral spines to trap food and carry it to the oral surface where it uses a specialized feeding apparatus (Aristotle's lantern) to graze and consume its food. Approximately 45% of the diet consists of algae attached to the urchin's burrows and the remainder is algal drift. Some of the macrophytic algae known to be consumed by this species include Dictyota sp., Chaetomorpha sp., Sargassum sp. and Laurencia papilosa , and it is also known to consume seagrasses in the genera Thalassia and Syringodium . Gut contents of some urchins have been observed to include spines from other echinoids (resulting from territorial fights), and sessile invertebrates.

• Primary Diet
• herbivore herbivore
  • algivore
• omnivore omnivore
• detritivore detritivore

• Animal Foods
• other marine invertebrates

• Plant Foods
• algae
• macroalgae macroalgae

• Other Foods
• detritus detritus

Predation

Predators include fishes, birds, molluscs, and humans. Triggerfish are able to break urchin tests with their strong jaws and consume the viscera, while gobies consume the urchin's tube feet and pedicellarie. Shorebirds, such as ruddy turnstones, flock over exposed reefs during low tide, pecking through urchin peristomes and eating the viscera. Conch use their radulae to drill through the urchin tests. Humans consume the gonads of this urchin.

This species is able to detect some invertebrate predators' odors and chemical signals, helping it to avoid predation. When attacked, an urchin waves its spines and tube feet as a defense and escape mechanism.

Ecosystem Roles

This species affects the development of coral reefs through shading, physical abrasion, and incidental ingestion of sessile epifauna, thus altering the community's physical and biological structure. Because it is mainly herbivorous, it has a strong impact on algal biomass, affecting the biodiversity and functionality of its ecosystem by increasing the access to substrate for the settlement, attachment and growth of other benthic organisms. In Brazil, reduction of algal cover helped recruitment of sponges ( Darwinela sp.). Most of this species' relationships are commensal. Some goby and clingfish species, as well as crustaceans, reside within its spines for protection. It is, however, also host to at least two species of ectoparasitic copepods.

• Ecosystem Impact
• creates habitat
• biodegradation biodegradation
• keystone species keystone species

Economic Importance for Humans: Positive

Humans consume the gonads of this species. This urchin can also serve as an indicator of marine pollution by the mercury levels found in its gonads. Humans benefit from this species' role in reducing algal overgrowth and in providing protection for small cleaning fishes, which helps to maintain the health of edible reef fish.

• Positive Impacts
• food food
• research and education

Economic Importance for Humans: Negative

This species is venomous, introducing its toxin via its spines. In Brazil it is responsible for approximately half of all accidents caused by marine animals. Effects of the venom range from mild, temporary discomfort to pain and secondary infections lasting for weeks.

• Negative Impacts
• injures humans
  • bites or stings
  • venomous venomous

Conservation Status

As of March 2012, there is no active conservation plan for this species. This species is not endangered.

Other Comments

This species is called by the common names red rock urchin or rock-boring urchin, but these names have also been applied to species such as Echinometra mathaei and Echinometra oblonga .

This species can survive exposure to direct sunlight for up to three hours although water temperatures of over 38°C are lethal.

Additional Links

Encyclopedia of Life

Contributors

Julio Plazas (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Jeremy Wright (editor), University of Michigan-Ann Arbor.

References

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