Black Longspine Urchin
Diadema antillarum
Black long-spined sea urchins are invertebrates in the family of echinoderms. They are related to sea stars, sea cucumbers, and sand dollars. They are easily identifiable by their black color and extremely long spines. They play a key role in coral reef ecosystems by controlling algae growth. An overabundance of algae can smother corals so these urchins are considered keystone species within their coral reef ecosystems. These urchins suffered a mass mortality event in the mid-1980s with the loss of over 90 percent of the population in the Caribbean. Several conservation programs are underway to raise and reestablish the population in the area impacted.
Credit: Aquarium of the Pacific
SPECIES IN DETAIL
Black Longspine Urchin
Diadema antillarum
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE:
At the Aquarium
Babies exhibit
Geographic Distribution
These urchins are found in the Western Atlantic from Florida, through the Caribbean down to Brazil as well as the Eastern Atlantic archipelagos of Madeira, the Gulf of Guinea, and the Canary Islands.
Habitat
The black longspine urchin can be found in coral and rocky reefs at depths of 0—400 meters (1,312 feet).
Physical Characteristics
This sea urchin has a round, hard skeleton body which is made of calcium carbonate and divided into ten sections. The black longspine urchin has long spines that can be four times the width of the test (calcium shell). The spines are used to protect it from potential predators and move to aid in feeding. Like other urchin family members, it does not contain a heart, brain, lungs, or blood. Tube feet extend from the test and provide mobility, breathing, food capture, and reproduction for the urchin. As part of its water vascular system, it operates the tube feet much like a hydraulic system for the suction cup ends of the tube feet to attach or release. The mouth of the urchin, which has five teeth, can be found on the underside of the urchin and is known as Aristotle’s lantern.
Size
The body consists of a calcium shell known as a test. Adult test can be 10 centimeters (4 inches) in diameter. The spines can extend 30 centimeters (11 inches) from the test.
Diet
Black long-spined urchins are primarily herbivorous, feeding on algae grown on corals or rocky reefs. In some cases where competition for food is high, they may also eat marine worms and zooplankton. Nocturnal feeders, the urchin will take cover in crevices or under ledges during the day as protection from predators then come out at night to feed. They use their tube feet to move over the coral and scrape algae off it with their teeth.
Reproduction
They use broadcast spawning reproduction. Females release eggs and males release sperm into the water and when they come in contact, fertilization occurs. The timing of the process is connected to the lunar calendar and water temperatures. Once fertilized, the egg develops into larvae, going through several stages of development that can last from four to six weeks. Larvae known as echinopluteus begin to develop tentacles and oral structures. Once settled on the ocean floor, they begin to develop their skeleton or test. From this point, development of the urchin continues and they become sexually mature during their second year of life.
Behavior
They are very sensitive to light and will respond to shadows over their body as possible predators. During the day they tend to hide in crevices or under ledges around reefs for protection, coming out at night to feed. They will quickly wave their long spines to deter predators.
Adaptation
They develop extremely long spines that have claw-like pincers on their ends called pedicellariae. The pincers contain a venom which can be irritating if it penetrates the skin. The extremely long length of the spines provides protection for small fish who hide in them from larger predators. The five hard teeth known as Aristotle’s lantern allow the urchin to scrape surface algae off rocks and coral reefs.
Longevity
Life expectancy for the black longspine urchin is four to six years, dependent on water temperature and food availability.
Conservation
The black longspine urchin has not been evaluated by the IUCN (International Union for Conservation of Nature) although it plays an important role in coral reefs in keeping algae growth in check that could destroy coral. Its role in controlling algae growth earn it the designation as keystone species in the coral ecosystems it inhabits. In addition, its long spines serve as protection from predators for juvenile and smaller species of fish. In the mid-1980s, a mass mortality event occurred with the species in the Caribbean. Over 90% of the urchin population died, resulting in loss of coral in the impacted area. No definitive cause was attributed to the event, and several smaller die offs have been observed recently. Several conservation programs are underway to raise the urchins in a controlled setting and reintroduce them to the coral reefs to restore their populations. Studies have shown that ocean acidification will have a negative impact on both the reproduction rates and strength of test development in the future.
Special Notes
The urchins, similar to their relatives the sea stars and sand dollars, do not have a bone in their body; the central hard test area is made up of calcium carbonate. The sea urchin name derives from the Old English name for the land based spiny hedgehog.
SPECIES IN DETAIL | Print full entry
Black Longspine Urchin
Diadema antillarum
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE:
Babies exhibit
These urchins are found in the Western Atlantic from Florida, through the Caribbean down to Brazil as well as the Eastern Atlantic archipelagos of Madeira, the Gulf of Guinea, and the Canary Islands.
The black longspine urchin can be found in coral and rocky reefs at depths of 0—400 meters (1,312 feet).
This sea urchin has a round, hard skeleton body which is made of calcium carbonate and divided into ten sections. The black longspine urchin has long spines that can be four times the width of the test (calcium shell). The spines are used to protect it from potential predators and move to aid in feeding. Like other urchin family members, it does not contain a heart, brain, lungs, or blood. Tube feet extend from the test and provide mobility, breathing, food capture, and reproduction for the urchin. As part of its water vascular system, it operates the tube feet much like a hydraulic system for the suction cup ends of the tube feet to attach or release. The mouth of the urchin, which has five teeth, can be found on the underside of the urchin and is known as Aristotle’s lantern.
The body consists of a calcium shell known as a test. Adult test can be 10 centimeters (4 inches) in diameter. The spines can extend 30 centimeters (11 inches) from the test.
Black long-spined urchins are primarily herbivorous, feeding on algae grown on corals or rocky reefs. In some cases where competition for food is high, they may also eat marine worms and zooplankton. Nocturnal feeders, the urchin will take cover in crevices or under ledges during the day as protection from predators then come out at night to feed. They use their tube feet to move over the coral and scrape algae off it with their teeth.
They use broadcast spawning reproduction. Females release eggs and males release sperm into the water and when they come in contact, fertilization occurs. The timing of the process is connected to the lunar calendar and water temperatures. Once fertilized, the egg develops into larvae, going through several stages of development that can last from four to six weeks. Larvae known as echinopluteus begin to develop tentacles and oral structures. Once settled on the ocean floor, they begin to develop their skeleton or test. From this point, development of the urchin continues and they become sexually mature during their second year of life.
They are very sensitive to light and will respond to shadows over their body as possible predators. During the day they tend to hide in crevices or under ledges around reefs for protection, coming out at night to feed. They will quickly wave their long spines to deter predators.
They develop extremely long spines that have claw-like pincers on their ends called pedicellariae. The pincers contain a venom which can be irritating if it penetrates the skin. The extremely long length of the spines provides protection for small fish who hide in them from larger predators. The five hard teeth known as Aristotle’s lantern allow the urchin to scrape surface algae off rocks and coral reefs.
Life expectancy for the black longspine urchin is four to six years, dependent on water temperature and food availability.
The black longspine urchin has not been evaluated by the IUCN (International Union for Conservation of Nature) although it plays an important role in coral reefs in keeping algae growth in check that could destroy coral. Its role in controlling algae growth earn it the designation as keystone species in the coral ecosystems it inhabits. In addition, its long spines serve as protection from predators for juvenile and smaller species of fish. In the mid-1980s, a mass mortality event occurred with the species in the Caribbean. Over 90% of the urchin population died, resulting in loss of coral in the impacted area. No definitive cause was attributed to the event, and several smaller die offs have been observed recently. Several conservation programs are underway to raise the urchins in a controlled setting and reintroduce them to the coral reefs to restore their populations. Studies have shown that ocean acidification will have a negative impact on both the reproduction rates and strength of test development in the future.
The urchins, similar to their relatives the sea stars and sand dollars, do not have a bone in their body; the central hard test area is made up of calcium carbonate. The sea urchin name derives from the Old English name for the land based spiny hedgehog.