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sea
stars text index | photo
index
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| Phylum Echinodermata > Class Stelleroida > Subclass Asteroidea |
| Knobbly
sea star Protoreaster nodosus Family Oreasteridae updated Aug 10
Where seen? This huge and colourful sea star is sometimes seen on Chek Jawa and some of our undisturbed Northern and Southern Shores. Adults are usually seen in coral rubble areas, alone or widely spaced apart. Juveniles are commonly seen on Cyrene Reef among seagrasses. These spectacular animals are the highlight of a shore trip! Features: Diameter with arms, adults to 30cm, juveniles 8-15cm. Hard, heavy body that is calcified. Arms long tapering to rounded tip, thick and triangular in cross-section. Although their arms appear stiff, these can bend quite extensively. When submerged tiny transparent finger-like structures (papulae) might be seen on the upperside. This species is generally identified by the single row of knobs along the upperside of the arms. The shape, colour and number of knobs may vary. Underneath, from grooves under the arms, emerge tube feet with sucker-shaped tips. These tube feet can be bright red or purple! Knobbly sea stars are mostly red, orange or brown, but sometimes white or pink ones are encountered. Blue or green ones are also sometimes seen. 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. What do they eat? According to Lane, it eats micro-organisms and scavenges on dead creatures. According to Gosliner, it probably feeds on sponges. According to Schoppe, it prefers to eat clams and snails but also eats sponges, soft corals and other invertebrates. According to Coleman the sea star hosts shrimps, scale worms, harlequin crabs and sea star crabs. Others report parasitic snails as well as. But these have not been observed on the Knobbly sea stars seen at low tide. Status and threats: 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. In the past, Knobbly sea stars were among the most common large sea stars of Malaya. They are now listed as 'Endangered' on the Red List of threatened animals of Singapore. Cyrene Reef is among the few places left in Singapore where they can be seen regularly. |
 Pulau Sekudu, May 04  Also in different colours. Beting Bronok, Aug 08  Underside Pulau Sekudu, May 04 |
They are no longer common on all our shores.
 Pattern on the underside |
 Tiny pedicellaria near the mouth. |
 Mouth. |
 Sometimes seen in contorted shapes. Beting Bronok, Jun 04 |
 Pink or purple tube feet. |
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 Juveniles are common on Cyrene Reef Cyrene Reef, Apr 08 |
 Papulae emerging on the upper surface. |
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Knobbly sea stars on Singapore shores
 With six arms. Cyrene Reefs, Jan 09 |
 With four arms. Cyrene Reefs, Jan 09 |
 Four-armed Beting Bronok, Jul 03 |
 Juvenile (about 15cm in diameter) Pulau Semakau, Aug 08 |
 Underside. |
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 Tiny pedicellaria on the underside. |
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 Brown and chocolate Beting Bronok, Jul 05 |
 White and pinkish Pulau Sekudu, Dec 03 |
 Green Cyrene Reef, May 11 |
 Blue Chek Jawa, Jul 08 |
 Green Changi, Jul 08 |
 Without knobs on the arms! Cyrene Reef, Nov 08 |
 Spawning posture? Cyrene Reef, Aug 11 |
 Spawning posture? Cyrene Reef, Aug 11 |
 Dying sea star Cyrene Reef, Aug 11 |
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more photos of knobbly sea stars on Singapore shores
northern shores part 1 | part 2 | part 3 | part 4 | part 5
southern shores part 1 | part 2 | part 3 | part 4
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Acknowledgements
With grateful thanks to Chim Chee Kong of the Star Trackers for identifying the sea stars. Links
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Times Edition, Singapore. 144 pp.|
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