What is choriaster?

''Choriasteris monotypic genus in the family Oreasteridae containing the single speciesChoriaster granulatus'' commonly known as the granulated sea star. Other common names include big-plated sea star and doughboy starfish.1 This species is harmless to humans.


Choriaster granulatus is a large sea star with a convex body and five short arms. The arms have rounded tips, making it appear "chubby", this is where its nickname "the doughboy starfish" comes from. Comparatively large to other seastars, the maximum growth radius is about 27 cm. Most commonly, it is a pale pink color with brown papillae in the center, but it can also be found in colors such as grey, yellow, and even red.2 3


This species is found in numerous tropical waters, including:4


<img src="Oreasteridae_-_Choriaster_granulatus.jpg" title="Choriaster granulatus in Madagascar" width="250" alt="Choriaster granulatus in Madagascar" />Choriaster granulatus prefers shallow waters, having a depth range of 1.5 – 53 m deep. The water temperature is above average, ranging from 24-29 °C.6 Choriaster granulatus has been found individually or in groups in the Indo-West Pacific region along coral reefs.7 It has also been found in the Red Sea, Fiji, and Great Barrier Reef.8 The sandy habitat is characterized by rubble slopes and detritus and they have been found among corals and sponges.9 <img src="Choriaster_granulatus.jpg" title="Choriaster granulatus" width="250" alt="Choriaster granulatus" />


Choriaster granulatus is a carnivore and has its mouth on the underside of its body, like other sea stars. Their prey is absorbed outside their mouths by forcing out their digestive organs from their stomach.10 Its prey include carrion and small invertebrates such as coral polyps.11

Life cycle and reproduction

Embryos hatch into planktonic larvae before becoming juveniles with five arms. These juveniles will grow up to be sea stars with stubby arms. The Asteroidea class of organisms use both asexual and sexual means of reproduction.12


The arms of Choriaster granulatus can become deformed when small parasitic limpets attach to the underside of the arms.13 There is also the threat of habitat loss, due to ocean acidification which leads to coral bleaching. 14


External links

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  1. Choriaster granulatus, granular sea star