Longspine Black Urchin (Diadema savignyi)

Also known as Banded Diadem Urchin, Black Longspine Urchin, Diadema Sea Urchin, Longspine Sea Urchin, Long-spined Black Urchin, Long-spined Sea Urchin, Long-spined Urchin, Needle-spined Urchin, Needle-spined Sea Urchin, Savigny's Longspine Sea Urchin, Sea Hedgehog, Tropical Spined Sea Urchin

Description

Also known as Banded Diadem Urchin, Black Longspine Urchin, Diadema Sea Urchin, Longspine Sea Urchin, Long-spined Black Urchin, Long-spined Sea Urchin, Long-spined Urchin, Needle-spined Urchin, Needle-spined Sea Urchin, Savigny's Longspine Sea Urchin, Sea Hedgehog, Tropical Spined Sea Urchin.

Found singly or in large groups hiding under rocks during the day becoming active at night over shallow waters often around harbours and wharfs especially where there has been storm damage.
They feed on algae.
Length - 25cm
Depth - 0-70m
Widespread Indo-Pacific

Differs from D. setosum (Needle Urchin) in that it lacks red ring around the anus but is the more common of the two in South Africa.

Sea Urchins use tubed feet to get around, often in large impenetrable masses for protection.
Sometimes they hitch a lift on the back of crabs.
They have well developed jaws for grinding their prey.
Their anus is on top in most sea urchins, except the heart urchins where it is at the rear.
Predators of sea urchins are triggerfish and large wrasses, who nibble away at their spines before turning them over to eat the fleshy undersides.
Sea Urchins are highly venomous and can piece through a wet-suit.
Some are sensitive to light and have the ability to shoot venom loaded spines at a short distance.
To be avoided!! Black urchin with extremely long needles. Dotted blue lines along the body. Ref: https://en.wikipedia.org/wiki/Diadema_savignyi

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