(DRAFT) - Taxonomy
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
TAXONOMY
NAME - urchin, long-spined black sea
OTHER COMMON NAMES - long-spined black sea urchin, black sea egg and spiny black sea urchin
ELEMENT CODE -
CATEGORY - Other Aquatic Invertebrate Taxa
PHYLUM AND SUBPHYLUM - Echinodermata,
CLASS AND SUBCLASS - Echinoidea,
ORDER AND SUBORDER - Aulodonta,
FAMILY AND SUBFAMILY - Diadematidae,
GENUS AND SUBGENUS - Diadema,
SPECIES AND SSP - antillarum, Philippi
SCIENTIFIC NAME - Diadema antillarum Philippi
AUTHORITY -
TAXONOMY REFERENCES - 2
Taxonomy - 1 (DRAFT) - Status
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
STATUS
Coded Status
Biological Indicator
REFERENCES FOR STATUS - 2
COMMENTS ON STATUS -
After the mass mortality of Diadema in 1983-84, changes in the algal
community that were predicted by previous experiments in which Diadema was
excluded occurred in the reef areas studied. Algal biomass increased
dramatically in Jamaica, Curaco, Panama, Puerto Rico, and St. Croix. In St.
Croix, areas previously grazed by Diadema supported algal communities with
biomass values 5-20 times higher than those present before 1983. Algal
biomass on several reefs in the Florida Keys appeared to undergo a less
marked increase, suggesting that Diadema was not the dominant herbivore
before mass mortality. Changes in algal species composition also occurred
after the dieoff. Reefs in Jamaica became dominated by the brown algae
Lobophora variegata and Dictyota spp. It was reported that shallow reef
areas in Panama became covered with Dictyota. One week after the mortality
of sea urchins in St. Croix, juvenile forms of the macroalgae Acanthophora
spicifera and Laurencia obtusa were evident within the algal turf
communites. Six months after the die-off, several macroalgal species were
predominant members of the algal community including Dictyosphaeria
cavernosa, Dictyota spp., Lobophora variegata, Amphiroa fragilissima, Jania
adherens, and Laurencia obtusa. Two years after the mass mortality, many
reef areas were dominated by the leathery macroalgae Turbinaria turbinata
and Sargassum spp. The mass mortality of Diadema had significant effects on
the primary productivity of algal communities on reefs as well. Five days
after the mortality event, primary productivity per unit area had decreased
by 33%, even though algal biomass had increased by 27% over the same period.
The decrease in primary productivity per unit algal biomass was even
sharper, dropping by 60%. After the initial decrease, productivity remained
low and was characteristic of levels in algal communities grazed only by
herbivorous fishes before sea urchin mortality. These patterns were most
evident in the reef zones where Diadema was previously most abundant. The
results of this natural experiment confirm that grazing by Diadema is a
primary structuring force in maintaining algal abundance and community
structure on reefs and support the hypothesis that Diadema has a positive
effect of the primary productivity of algal communities on reefs.*2*
Status - 1 (DRAFT) - Distribution
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
Habitat Associations - 1 (DRAFT) - Food Habits
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
HERBIVORE/GRAZER
REFERENCES FOR TROPHIC LEVEL - 2
LIFESTAGE FOOD FOOD PART
General Rooted aquat. plant Not Specified
Important Anthozoans Not Specified
REFERENCES FOR GENERAL FOOD - 2
REFERENCES FOR IMPORTANT FOOD - 2
COMMENTS ON FOOD -
Diadema is a generalized herbivore that exploits a wide variety of plant
foods. Diadema is a grazer, scraping the hard substrate of the reef and
ingesting plant material along with coral rock. It has been implicated in
the bioerosion of coral reefs in the West Indies. Since stomach contents
average over 90% calcium carbonage, an average population of Diadema (10 per
meter squared) can produce as much as 5 kg of carbonate sediment per square
meter per year by scraping the carbonate rock surfaces of coral reefs. This
corresponds to about 1 cm of reef erosion per year. The foraging behavior
of Diadema can be studied by using spine tags. After nightly feeding
forays, individuals return with remarkable fidelity to the same daytime
hiding place. Diadema avoids grazing areas near the home crevices that have
been grazed the previous night. In this way, the urchins may maximize their
food intake relative to the production of algae. Diadema apparently senses
the quality of a crevice it occupies in providing protection from predators.
It vacates low-quality crevices more readily than high-quality when
disturbed.*2*
Food Habits - 1 (DRAFT) - Environment Associations
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Turbidity: Clear water
G Water Temperature: Specified in Comments
G
G Dissolved Oxygen: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 2
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Diadema requires relatively clean, highly oxygenated, circulating water.
It is most abundant on hard coral reef or rock surfaces where wave action
is light to moderate, but is often found on lagoonal sandy bottoms or in
seagrass meadows. Like most coral reef organisms, Diadema has a narrow
range of tolerance to changes in temperature and salinity. It is sensitive
to desication and is rarely found in area that are exposed at low tide.
Diadema avoids still, shallow water that may become superheated (above 35
deg. C) during the day. It is not found near the mouths of rivers and
streams or on reef flats where the seawater may be diluted to a salinity of
less than 30 ppt by runoff or periodic rainstorms. Diadema is difficult to
keep in aquaria and will die in a short time after collection if kept in a
crowded container. Diadema densities can be high in the vicinity of sewage
outfalls. This may be a result of nutrients simulating algal growth or of
direct uptake of dissolved organic material by the urchin. One of the
major effects of development in the Caribbean is uncontrolled sedimentation
from the runoff of cleared lands or from dredging. Diadema appears to be
more tolerant to sedimentation than corals, but will disappear from areas
where sedimentation is heavy. Sediemnt affects urchins by abrasion,
smothering, and by cutting off light necessary for algal growth.*2*
Environment Associations - 1 (DRAFT) - Life History
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
LIFE HISTORY
Diadema antillarum is one of six species of the genus now recognized in the
tropical oceans of the world. The test of Diadema is circular, slightly
flattened from top to bottom, and up to 10 cm in diameter; the spines are up
to 30 cm long. The test is delicate and, unlike those of other sea urchins,
is rarely found whole on the beach or on the bottom. In contrast to other
Caribbean urchins, such as Lytechinus and Tripneustes, Diadema does not
cover itself with pieces of vegetation, shell, or rock.*2*
Diadema is uniformly dark purple or almost black when mature, but in the
young (to 2 cm in diameter) the spines may be banded with white. Adults
occasionally have patches of white spines and very rarely are completely
white. Rows of brilliant blue spots, sometimes fused into lines, amy
radiate from the anal region on the top of the test. These spots may be
light sensors, and are often hidden by dark pigment. The region around the
anus (periproct) sometimes appears swollen into a bulge or finger of thin
tissue called the anal cone which is apparently produced by hydrostatic
pressure from the gut.
Spines
The primary and shorter secondary spines of Diadema are highly mobile and
attached by muscles to tubercles on the test. The largest tubercles are
organized into five double rows, giving the test a banded appearance. The
spines are thin, delicate, and hollow containing glandular tissue that
produces a toxin. The spines can penetrate human tissue and sometimes break
off, causing severe pain that lasts for several hours, and occasionally
allergic reactions. The spines are eventually absorbed by the body, or may
be dissolved by the application of a mild acid such as lemon juice or
vinegar. The skin may have a tatooed appearance from the spine pigment long
after the spines are absorbed. Then Diadema is disturbed, the spines point
at the source and wave about. They are covered with small barbs directed
toward the spine tip that help prevent predators from reaching the test.
Tube Feet and Pedicellariae
The other major external appendages of Diadema are the tube feet and
pedicellariae. The tube feet penetrate the test in rows of holes that
connect to the water vascular system, unique to the echinoderms. The tube
feet are thin, sensitive, and capable of extreme extension. They have a
terminal disc, or sucker, which enables Diadema to hold tenaciously to
smooth surfaces. The adhesive tube feet on the lower surface of the test
along with the spines are the major organs of locomotion; the tube feet on
the upper surface of the test are not very adhesive and are used in
respiration. The pedicellariae are morphologically equivalent to the spines
and consist of a head composed of three movable jaws, mounted on a stalk
that is attached to a tubercle on the test. The pedicellariae are very
numerous in the area surrounding the mouth (perisotme), and may be involved
in food handling. They also function in defense and in cleaning the test.
Reproduction
Diadema becomes sexually mature at a variable size, ranging from about 3 to
6 cm in test diameter. In the Caribbean, Diadema have been found in
spawning conditions throughout the year, though spawning appears to be
concentrated from late winter to early summer. Fertilization takes place
externally. Mass spawnings appear to be commonplace and may be triggered by
spawning up-current that eventually spreads through a whole population.
Spawning is observed when slender streams of yellowish eggs or white sperm
Life History - 1 (DRAFT) - Life History
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
are extruded from the top of the test from five gonopores surrounding the
anus. Spawning may be induced by application of pressure to the test in the
field, or by the disturbances associated with collection.
Recruitment
After a planktonic larval life of unknown duration, Diadema larvae settle to
the bottom and metamorphose into tiny sea urchins. They are first seen when
they attain a test diameter of about 1 cm, within 1 to 2 months after
settlement. Juveniles are secretive, live under rocks and in crevices, and
appear to be very vulnerable to their many fish predators. Like the adults,
they are most easily seen at night, when they emerge from their hiding
places to move about and feed.
Growth
Diadema grows rapidly at first, as fast as 5 mm in test diameter per month
an then gradually slows to 1-2 mm per month at a test diameter greater than
6 cm. Diadema usually attains a test diameter of 25-30 mm in the first year
and is 45 to 50 mm in the second year. Growth rate slows markedly in
urchins with test diameters greater than 6 cm and the maximum size attained
by Diadema within 3 to 4 years is about 10 cm. The size frequency
distributions of Diadema measured in the field are distinctly bimodal, with
a broad range in the largest size class. Given that the urchins attain
maximum size within 3 to 4 years, the larger size class in any population is
likely to be an accumulation of urchins 2 years old and older. Although it
is not known how long Diadema lives, 4 years is a reasonable low estimate if
the urchins die when growth ceases.*2*
Life History - 2 (DRAFT) - Management Practices
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Controlling sedimentation
Adverse Salinity alteration
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 228
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 228
COMMENTS ON MANAGEMENT PRACTICES -
Diadema requires relatively clean, highly oxygenated, circulating water. It
is most abundant on hard coral reef or rock surfaces where wave action is
light to moderate, but is often found on lagoonal sandy bottoms or in
seagrass meadows. Like most coral reef organisms, Diadema has a narrow
range of tolerance to changes in temperature and salinity. It is sensitive
to desication and is rarely found in areas that are exposed at low tide.
Diadema avoids still, shallow water that may become superheated (above 35
degrees C) during the day. It is not found near the mouths of rivers and
streams or on reef flats where the seawater may be diluted to a salinity of
less than 30 ppt by runoff or periodic rainstorms. Diadema is difficult to
keep in aquaria and will die in a short time after collection if kept in a
crowded container.
Diadema densities can be high in the vicinity of sewage outfalls. This may
be a result of nutrients stimulating algal growth or of direct uptake of
dissolved organic material by the urchin.
One of the major effects of development in the Caribbean is uncontrolled
sedimentation from the runoff of cleared lands or from dredging. Diadema
appears to be more tolerant to sedimentation than corals, but will disappear
from areas where sedimentation is heavy. Sediment affects urchins by
abrasion, smothering, and by cutting off light necessary for algal
growth.*228*
Management Practices - 1 (DRAFT) - References
Species urchin, long-spined black sea
Species Id M090005
Date 26 AUG 96
References
2 * Ogden, John C. and Robert C. Carpenter. 1987. Species profiles:
Life Histories and Environmental Requirements of Coastal Fishes
and Invertebrates (South Florida)--Long spined Black Sea Urchin.
U.S. Fish and Wildlife Service Biol. Rep. 82(11.77) pp 17.
References - 1