Tag: Long-Spined Sea Urchin (Diadema Setosum)

The Long-Spined Sea Urchin (Diadema Setosum) is by far the most common species of Sea Urchin in local waters and can be found at all of the sites visited.

This species is very easy to identify with its long, narrow, needle-like spines, protruding from a "test" (the globe-like body structure) which reaches a maximum diameter of around 10cm.

The spines are most often black in colour, although they may occur lighter or with banding on occasion.

The spines, which form the Urchin's primary defense against predators such as the Titan Triggerfish (Balistoides Viridescens), are mildly venomous and pose no danger to humans, although can cause extreme pain at the point of contact.

The Long-Spined Sea Urchin can be distinguished from its close relatives primarily by the presence of 5 white spots around the test and also a bright orange ring around the "periproctal cone" (the soft structure visible at the center of the test). There are also numerous small blue spots present in rows around the test.

Although this species can be found nestled in crevices within coral reefs, it is at its most abundant on sand flats at various depths, where large numbers often congregate to feed on various species of algae.

The Long-Spined Sea Urchin (Diadema Setosum) is by far the most common species of Sea Urchin in local waters and can be found at all of the sites visited.

This species is very easy to identify with its long, narrow, needle-like spines, protruding from a "test" (the globe-like body structure) which reaches a maximum diameter of around 10cm.

The spines are most often black in colour, although they may occur lighter or with banding on occasion.

The spines, which form the Urchin's primary defense against predators such as the Titan Triggerfish (Balistoides Viridescens), are mildly venomous and pose no danger to humans, although can cause extreme pain at the point of contact.

The Long-Spined Sea Urchin can be distinguished from its close relatives primarily by the presence of 5 white spots around the test and also a bright orange ring around the "periproctal cone" (the soft structure visible at the center of the test). There are also numerous small blue spots present in rows around the test.

Although this species can be found nestled in crevices within coral reefs, it is at its most abundant on sand flats at various depths, where large numbers often congregate to feed on various species of algae.

Alan's picture
Long-Spined Sea Urchin (Diadema Setosum)

A close-up of the very common, Long-Spined Sea Urchin (Diadema Setosum).

Clearly visible in this shot are the two main characteristics of this species ie: the five white dots around the edge of the "test" and the orange ring around the "periproctal cone".