Spiny Sea Urchin (Diadema setosum)

Also known as Setosum Spined Urchin, Diadem Urchin, Diadem Sea Urchin, Long-spined Sea Urchin, Black Longspine Urchin, Long-spined Black Sea Urchin, Pacific Long-spined Black Sea Urchin, Hatpin Urchin, Needle-spined Urchin.

Description

Also known as Setosum Spined Urchin, Diadem Urchin, Diadem Sea Urchin, Long-spined Sea Urchin, Black Longspine Urchin, Long-spined Black Sea Urchin, Pacific Long-spined Black Sea Urchin, Hatpin Urchin and Needle-spined Urchin.

Found in large groups moving across the sand and rubble in bays and lagoons.
Identified by the light coloured ring around the anal cone at the centre.
They feed on invertebrates, sponges and even dead fish.
Length - 20cm
Depth - 0-20m
Widespread Indo-Pacific

These large sea urchin with long and mobile spines can often be found with fish swimming in between their spines for protection.

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!!

3 comments

  1. Posted by ramesh
    May 06, 2014 at 02:38 am - 1 person found this useful.

    I have attacked by these fish in pattaya beach. It is so painful and I had antibiotics capsules. so please be careful while swimming in certain places in Bangkok beaches. It is often found near the coral reef islands.

  2. 3 aspects i have come across 1) they often have vibrio contamination (as does coral etc) and cause symptoms for months, so an appropriate antibiotic is usually appropriate early on (doxycycline/cipro). 2) i have read (hear say evidence) of paralysis and nasty things happening after innocuous stings from urchins weeks later.! 3)Been pricked myself and nothing happened.(but i went fishing under Local anaesthetic to get all the bits out)

  3. Posted by Phillip
    February 03, 2013 at 19:36 pm - 1 person found this useful.

    A patient of mine was 'stung' multiple times by one of these sea urchins leaving part of their sting in the skin. It was painful at the time but these spike tips are still embedded in the skin. Anyone know what the consequences are if these tips are left in? Please advise.

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Known Sightings / Photograph Locations

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