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Knobbly
sea star
Protoreaster nodosus
Family Oreasteridae |
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On
Chek Jawa, these spectacular sea stars can be rather numerous at times
in the coral rubble area. They are also sometimes seen on the northern
arm of the sand bar and in the seagrass lagoon.
Knobbly parts: Knobbly sea stars
are not venomous, although they are often brightly coloured and covered
with dangerous-looking knobs, nodules and spines. They are also called
the Giant Nodulated sea star, Horned sea star or Chocolate Chip sea
star. They have thick, triangular arms. Although their arms appear
stiff, these can bend quite extensively. Knobbly sea stars are mostly
red, but sometimes, white or brown ones are encountered on Chek Jawa.
Blue or green ones have been recorded in the past. Their knobs may
be black or brown and come in various patterns and arrangements. Like
other sea stars, they have tube feet emerging from the grooves under
their arms. These tube feet can be bright red or purple!
Knobbly food: The Knobbly sea
star prefers to eat snails and clams, but will also eat sponges, soft
corals and other small creatures. It is also reported to eat algae
and scavenge on dead creatures.
Knobbly Babies: Like other sea
stars, Knobblies practice external fertilisation. Eggs and sperm are
stored in their arms and released simultaneously into the water. It
is reported that they gather in large numbers to spawn. Like other
sea stars, Knobblies undergo metamorphosis and their larvae look nothing
like the adults. The form that first hatches from the eggs are bilaterally
symmetrical and free-swimming, drifting with the plankton. They eventually
settle down and develop into tiny sea stars. Here is a fascinating
photo
of a sea star larva on Image
Quest 3-D Marine Library.
Human uses: Knobbly sea stars
are harvested from the wild for the live aquarium trade, often selling
for only a few dollars. In captivity, they are unlikely to survive
long without expert care.
Status and threats: In the past,
Knobbly sea stars were among the most common large sea stars of Malaya.
They are now listed among the threatened animals of Singapore. Chek
Jawa is among the few places left in Singapore where they can be seen
regularly. |
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White Knobbly
Pink tube feet!
Out-of-shape Star |
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quick
facts
Diameter with arms to about 30cm, seasonally common on the
coral rubble area and sometimes on the northern arm of the sand bar.
Classification:
Class Asteroidea
Phylum Echinodermata |
