The calcareous rings of two species of local sea cucumbers, Stichopus hermanni Semper and
Holothuria atra Jaeger, were located, dissected, exposed and recorded. The calcareous rings of both
species each composed of ten plates knit together by connective tissues. The radial plate of H. atra was
a square with a notch at the anterior part whereas in S. hermanni it was squarish consisting of 4 ridges
in the anterior part with a notch at the posterior part. The interradial plates of both species were
smaller than the radial plates. A ridge was present at the anterior part of the interradial plate in H.
atra. In S. hermanii, the ridge at the anterior part of the interradial was thin and prominent. Under the
scanning electron microscope the calcareous rings from the two species exhibited a mosaic of small,
numerous spicules bound to each other.
Key words: Holothuria atra Jaeger, Stichopus hermanni Semper, sea cucumber, calcareous rings,