The Starfish of Hong Kong, Part 1

Crown-of-Thornes (Acanthaster planci)

Crown-of-Thornes starfish

The crown-of-thorns starfish is a large starfish with many arms that preys on hard coral. Its name comes from the venomous thorny spines covering its upper surface – meant to resemble the crown of thorns put on Jesus before his crucifiction. This is one of the largest starfish and has a very wide distribution in the Indian and Pacific Oceans at tropical and subtropical latitudes where coral reefs or hard coral communities occur.

The venom of the starfish contains so-called asterosaponins which have detergent-like properties. The brittle spines can perforate the skin of a predator or unwary diver and tissue containing the venom is lodged into the resulting wound. In humans this immediately causes a sharp, stinging pain lasting several hours, with persistent bleeding aided the venom as well as nausea, tissue swelling lasting for a week or more. Breaking of the spines means they become embedded in the tissue where they require surgically removal.

Peppermint Sea Star (Fromia monilis)

The peppermint sea star can grow to a diameter of about 30 centimetres. Its arm tips and the central disc are bright red, while the other parts are paler, forming large plates. The color, plates and other features can be very variable and identification from photographs can be difficult. It feeds on encrusting spongess, detritus and small invertebrates. Occurs in shallow water in rocky environment, at a depth of 0 – 51 m.

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hkmarinelife

I am a ex-marine biologist but I am still passionate about marine biology and oceanography. I studied Marine Science and completed a PhD in deep-sea ecology and biodiversity. I fell in love with HK's rich marine environment when I was a child. This blog is my collection of interesting facts, news and articles that celebrate and educate on HK's diverse marine environment.

2 thoughts on “The Starfish of Hong Kong, Part 1”

  1. Hello, may I know if the Crown-of-Thornes starfish picture was taken in Hong Kong water, and if so, where was it spotted?

    1. Hi. No the picture is from WikiCommons. I was in two minds whether to include the Crown-of-Thorns in the list, because I cannot actually find a record of it in Hong Kong in the English literature. But I include it because it occurs in Hainan to the West, Xisha Islands to the south, and Taiwan to the east. In fact temperature is no barrier because it also occurs northerly at the Ryukyu Islands. And Hong Kong has hard coral communities that can support them – in other words it would be very strange if they did not occur here, too. But it’s not actually recorded as far as I know.

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