Page 311 - (DK) Ocean - The Definitive Visual Guide

ECHINODERMS 309

CLASS ASTEROIDEA Occasional plagues of this large and high input of nutrients from land. With out through their mouth
destructive starfish sometimes kill up to 20 arms and a formidable and digesting the coral’s living tissue.
Crown-of-thorns extensive areas of coral on the Great covering of long spines, this species has Pure white coral skeletons indicate
Barrier Reef of Australia on reefs in few predators. The spines are mildly that this starfish has been feeding
Starfish the Indo-Pacific. There has been venomous and may inflict a painful recently in the area. In popular
much debate on whether such plagues wound if the starfish is picked up with diving tourism areas, attempts are
Acanthaster planci
are natural or are caused by over- bare hands. Crown-of-thorns starfish often made to kill the starfish by
DIAMETER fishing of their few predators, such as feed on corals by turning their stomach injecting them with poison or
Up to 20 in (50 cm)
the giant triton, Charonia tritonis (see removing them by hand, but
DEPTH p.285). Land run-off appears to with only limited success.
3–65 ft (1–20 m)
stimulate plagues. Recent A new experimental injection
HABITAT research on the Great that promotes bacterial
Coral reefs
Barrier Reef suggests growth and induces an
DISTRIBUTION Tropical waters of Indian and Pacific that some outbreaks immune response may
oceans
are caused by prove effective.

CLASS OPHIUROIDEA
Common Brittlestar

Ophiothrix fragilis
DIAMETER Up to 5 in
(12 cm)
DEPTH 0–500 ft (0–150 m)
HABITAT Rocks, rough
and gravely ground

DISTRIBUTION Temperate and warm waters of
eastern Atlantic
CLASS OPHIUROIDEA
arm coiled This large brittlestar species gathers
Serpent Star around black in dense groups that may cover several
coral branch
square miles of sea bed in areas where orange to brown and gray, and they
Serpent stars are a type of brittlestar there are strong tidal currents. They often have alternate light and dark
Astrobrachion adhaerens
DIAMETER Up to 12 in with long, flexible arms. During the have been recorded at densities of bands on the arms. The fragile arms
(30 cm) day they wind their arms tightly 2,000 individuals per square yard. of this species are covered in long,
DEPTH 50–600 ft round the branches of the deep-water Each brittlestar holds up one or two untidy spines, while its small disk,
(15–180 m) black corals in which they live. At arms into the current to feed on which is only 1 in (2 cm) across, has
HABITAT Antipatharian night they uncoil their arms and move plankton, while linking its remaining a covering of shorter spines. In the OCEAN LIFE
black corals around, feeding on the living polyps arms with surrounding individuals to intertidal zone, common brittlestars
DISTRIBUTION Tropical and temperate waters of of their host. A black coral bush one form a strong mat and prevent itself are not usually found in groups, but
Australia and southwestern Pacific or two yards high may be host for being swept away. They vary greatly occur as individuals hiding in crevices
up to forty or so serpent stars. in color, ranging from red, yellow, and and beneath stones.