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November 28, 2011
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Sea Urchin Anatomy by Abiogenisis Sea Urchin Anatomy by Abiogenisis
[This image is available for purchase, and alternations can be made on request]

Illustrated is the generalised internal and external features of a typical arbacia-type sea urchin. Several features such as gills and the pedicilaria were omitted as they are outside the scope of this image.

Sea urchins are globular, superficially pentamerically symmetrical echinoderms which inhabit marine environments world wide. Movement across the substrate can be made in one or both of two ways: The defensive spines can be moved independently and thus act as mobile stilts in the long spined species, or the hydraulically extended tube-feet can be employed for both mobility and anchorage.

These tube feet are part of an internal network of water filled tubes and bladders called the water vascular system. This network is connected to the seawater via a structure called the madreporite on the aboral (upper) surface: When the bladders along the radial canals contract, they inflate and thus extend the tube feet.

The sea urchin feeding apparatus is a five sided complex articulated structure called the Aristotles' Lantern. It consists of a series of interlinked plates and muscles which manoeuvre five continuously growing teeth, used to rasp away at algae, their predominant food source.

The nervous system is relatively simple, centred around a nerve ring inside the lantern from which radiate five nerves to innervate the radial water vascular system.
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Quadroblitz Featured By Owner Edited Jun 19, 2014  Hobbyist Traditional Artist
It looks like a space pod. Like the blue things are seats there's a light at the top and I dunno, air conditioning over there. And there's a control panel in the middle.
Abiogenisis Featured By Owner Jun 23, 2014
So utterly strange.
Quadroblitz Featured By Owner Jun 23, 2014  Hobbyist Traditional Artist
Yea I guess it is.
jpilbrow Featured By Owner Jan 29, 2014
Hi, I am looking for an image illustrating sea urchin morphology to use for my PhD thesis and this is the best that I have come across. The thesis is for academic use only, it will not be sold or reproduced, but a copy may be available to view online and in the university library, proper credit for the image will be given. Please email me in regards to this ASAP at Thanks Jodi   
XSONOHX Featured By Owner Nov 14, 2013  Hobbyist Traditional Artist
I was looking at pictures of Sea Urchins and found this, looks cool.
Abiogenisis Featured By Owner Nov 19, 2013
Cheers, it was one of the hardest and most enjoyable projects I ever did :)
hannahelizabethh Featured By Owner Nov 8, 2013  Student General Artist
is this anatomically/scientifically/body parts correct to the real ones in the ocean?? cause its sooo cool! :D  
Abiogenisis Featured By Owner Nov 11, 2013
They should be! I tried to find as much research material as I could :P
hannahelizabethh Featured By Owner Nov 12, 2013  Student General Artist
justin5578 Featured By Owner Oct 22, 2013
As a scuba diver in Southern California I'm all too familiar with urchins as they have decimated kelp forests (thanks to humans taking their natural predators), I am however fascinated by them.  I have a collection of sea urchin tests (skeletons) that I have collected on my many dives.  I have to say your picture makes me all the more fascinated.  Nice work.
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