WHATSTHATFISH
Sea stars & urchins

Slate Pencil Urchin

Heterocentrotus mamillatus

Also known as: Burrowing Urchin, Pencil Urchin, Red Pencil Urchin, Red Slate Pencil Urchin, Sea Hedgehog, Heterocentrotus mammillatus

Adult
@fishx6 · Hawaiian Islands, United States · June 20161 / 8
01

Overview

Found burrowed, into coral or limestone areas over sub-tidal zones of the reef.

The spines on the side of these sea urchins are worn down by continual abrasion trying to stay in the hole while the longer dorsal spines act as a defence against predators.

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.

02

How to identify

COLOURS
Body shape
fingers
Behaviour
burrowing

Tap any trait to see other fish that share it.

03

Habitat & where to find it

  • Range · Indo-Pacific
  • Exact location · 2
  • Dive site · 6
LIVES IN

Found burrowed, into coral or limestone areas over sub-tidal zones of the reef.

04

Adult photos 8

05

Discussion

Comments are checked by a moderator before they appear.

No comments yet. Seen one, or got a question about it? Start the discussion.

    ALL STAGES
    FOR THE MARINE-BIOLOGY CURIOUS

    Deep dive

    Taxonomy

    1. kingdomAnimalia
    2. phylumEchinodermata
    3. classEchinoidea
    4. orderCamarodonta
    5. familyEchinometridae
    6. genusHeterocentrotus
    7. speciesHeterocentrotus mamillatus (Linnaeus, 1758)

    SourcesWoRMSWikipedia

    06

    More in the family

    Sea Urchins (Echinometridae)