Spiny Sea Urchin (Diadema setosum)

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

Description

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

Found singly or in large groups moving across rubble, sand, shingle and seagrass beds in bays and lagoons.
They feed nocturnally on algae.
Length - 20cm
Depth - 0-70m
Widespread Mediterranean, Indo-Pacific

Amongst their spines these sea urchins may have Banggai Cardinalfish - Pterapogon kauderni
http://www.whatsthatfish.com/fish/banggai-cardinalfish/6
Tubed Cardinalfish - Siphamia tubifer
http://www.whatsthatfish.com/fish/tubed-cardinalfish/3024

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!!
Ref: https://en.wikipedia.org/wiki/Diadema_setosum

7 comments

  1. Posted by William Dean
    July 21, 2018 at 18:04 pm - 1 person found this useful.

    These are now in the Med. There were a load of them near Marmaris/ Dalaman on the rocky coast.

  2. Posted by Hazel Smith
    May 22, 2016 at 02:44 am - 1 person found this useful.

    I accidentally whacked a Black Sea urchin whilst swimming backstroke in shallow water in Thailand. A rock under surface! I hit it as hard as I possibly could with the palm of my hand. The pain was incredible! A few days later I pulled a 2+cm long spine out from the palm of my hand. 2 x Ray's and an ultrasound scan a few weeks later and everyone kept reassuring me everything was fine, nothing showing. An hour long surgery 4 months later to remove spine tips and a massive scar!

  3. Posted by Bahar Algon
    September 01, 2015 at 21:44 pm - 1 person found this useful.

    When the needles get in the skin put some olive oil on a cotton pad. Tie it around and the next morning the needle is gone. Painless and a sure solution.

  4. 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.

  5. 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)

  6. 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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