Sealife guideThe mosaic sea starPlectaster decanus

Last updated on 08/10/2026 at 10:24 PM
Taxonomy
English names Mosaic sea star
French namesEtoile de mer mosaïque
Spanish namesEstrella mosaico
Scientific namePlectaster decanus (Muller & Troschel, 1843)
FamilyEchinasteridae
OrderSpinulosida
ClassAsteroidea
Description
The mosaic sea star is a five-armed sea star distinguished by its geometric patterns, which form a mosaic with very bright yellow or even whitish seams. Its main color is generally bright red, but the mosaic sea star can sometimes display a darker red coloration as well as areas of different colors.
L'étoile de mer mosaïque (Plectaster decanus) est revêtue d'une belle mosaïque rouge aux joints d'un jaune vif !
L'étoile de mer mosaïque (Plectaster decanus) est revêtue d'une belle mosaïque rouge aux joints d'un jaune vif ! © | Dreamstime.com
Geographic range
The mosaic sea star is a sea star endemic to the southern coast of Australia. It is found from Perth on Australia's west coast to Brisbane on the east coast, passing through Adelaide, Melbourne and Sydney.
Habitat
The mosaic sea star inhabits rocky reefs at depths ranging from 33 feet to more than 492 feet.
Diet
The mosaic sea star feeds mainly on sponges.
Did you know ?
The mosaic sea star is one of the few venomous sea star species. It can cause numbness in humans when handled for an extended period of time.
The mosaic sea star (Plectaster decanus)
The mosaic sea star (Plectaster decanus) © | Dreamstime.com
Within the same family
Red starfish
Red starfishEchinaster sepositus
Discover also
Blue spiny starfish
Blue spiny starfishCoscinasterias tenuispina
Chocolate chip sea cucumber
Chocolate chip sea cucumberIsostichopus badionotus
Hatpin sea urchin
Hatpin sea urchinCentrostephanus longispinus
Heavy starfish
Heavy starfishThromidia catalai
Purple sun star
Purple sun starSolaster endeca
Slate pencil urchin
Slate pencil urchinHeterocentrotus mamillatus
Sunflower sea star
Sunflower sea starPycnopodia helianthoides
West Indian sea egg
West Indian sea eggTripneustes ventricosus
The marine species in Australia
Australian spiny gurnard
Australian spiny gurnardLepidotrigla papilio
Eastern clown anemonefish
Eastern clown anemonefishAmphiprion percula
Giant barrel sponge
Giant barrel spongeXestospongia testudinaria
Horned sea star
Horned sea starProtoreaster nodosus
Long-finned pilot whale
Long-finned pilot whaleGlobicephala melas
Tawny nurse shark
Tawny nurse sharkNebrius ferrugineus
Whitespotted wedgefish
Whitespotted wedgefishRhynchobatus australiae
Yellow shrimp goby
Yellow shrimp gobyCryptocentrus cinctus
Best scuba diving destinations
The Sydney Opera House
The Sydney Opera House

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