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Red Sea Urchin

Astropyga radiata


Astropyga radiata, the red urchin, fire urchin, false fire urchin or blue-spotted urchin, is a species of sea urchin in the family Diadematidae. It is a large species with long spines and is found in the tropical Indo-Pacific region. It was first described in 1778 by the German naturalist Nathaniel Gottfried Leske. Astropyga radiata is a large urchin with a test diameter of up to 20 cm (8 in), flattened or slightly concave on the aboral (upper) side. The spines are up to 4 cm (1.6 in) long and are grouped in five vertical clusters in between which are V-shaped areas with no spines corresponding to the interambulacral plates. These bare areas are red with lines of iridescent blue dots while the colour of the rest of the test and spines varies from reddish-brown to purple, dark brown or nearly black. The spines are long and hollow ; they are of two kinds, the shorter being venomous. The anal sac is prominent, brown with a dark tip. Juveniles have spines with transverse banding and this characteristic sometimes persists into adulthood.


Astropyga radiata is found in the Indo-Pacific Ocean at a maximum depth of about 70 metres (230 ft) but more normally at 10 to 30 metres (33 to 98 ft). Its range extends from the African coast to Hawaii and Australian waters. It is often found in lagoons and bays where the substrate is sand, shingle or coral rubble. Sometimes many urchins collect together in one locality in dense aggregations

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Mark Ridgway
Mark Ridgway 9 years ago

Fantastic animals. Thanks Albert.

AlbertKang 9 years ago

Thanks, @sunnyjosef :)
Actually, this are fairly common critters. Although not seen in all dive sites, you can see them in great numbers, sometimes in the hundreds at certain dive sites, especially sandy areas.

The more interesting critters are not just the Sea Urchins but Shrimps and Crabs that sometimes lives on them :)

sunnyjosef 9 years ago

Wow!1 You are showing us unseen creatures Albert.. TFS

AlbertKang 9 years ago

Thanks, @Bhagya and @Adarsha.

Adarsha B S
Adarsha B S 9 years ago

Awesome spotting Albert!

Bhagya Herath
Bhagya Herath 9 years ago

Beautiful spotting....

AlbertKang 9 years ago

Thanks, @Marta :)

The MnMs
The MnMs 9 years ago

Beautiful urchins, Albert!

Spotted by

Mabini, Calabarzon, Philippines

Spotted on Aug 16, 2014
Submitted on Aug 19, 2014

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