Homage to Aristotle

The complete intestine of S. affinis

After opening the test via the peristomal plating, we were able to extract the intestines of the sea-urchin Stylocidaris affinis.

Because it was a dried sample, it was possible to obtain the intestines intact.

We will not further examine the intestines. But further research could be pursued:

  • Analyzing the internal characteristics (taxonomy)

  • Molecular analysis (taxonomy)

  • Stomach content analysis (Ecological function



Encompassed by a fleshy tissue permeated with bony plates, the jaw of the sea-urchins has already gained special attention by the famous philosopher and naturalist Aristotle (384-322 BC). The pyramid like structure, equipped with five calcium carbonate teeth reminds of a lantern.

The analysis of the lanterns of both species of interest showed no obvious difference. However, we found a difference in the molecular composition of the teeth. Further research would be necessary to rule out the origin of this small, but interesting difference.

Intact (S. affinis) lantern

The fascinating jaw of sea-urchins makes us think about different live forms, and the surprising structures evolution has produced.

Disassembled lantern on a SEM stub mount

No obvious differences could be found with the small magnification of stereomicroscopes.

Therefore, we will venture deeper into the small structures that can only made visible through greater magnification.