Mellita isometra
Family Mellitidae

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Note: Beam trawls used in the Transect Program do not adequately collect burrowing organisms,
so the distribution and abundance of this species is not well documented.

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This is a common irregular sea urchin, often referred to as a "sand dollar" or "key-hole urchin."
There are five lunules (the slot-like holes), and 5 distinct, elongate petals on the aboral side.
Note the short spines and tube feet that aid in burrowing. The edges of the specimen depicted are not
smooth (as would be typical), possibly due to breakage during its growth. Test width is ~9 cm.


These tiny specimens are only 2 cm long. They may be juveniles of
Mellita isometra (or, possibly Encope aberrans), as they have 5 distinct
slits on the disc. Note the numerous plates that make up the disc.
The individual on the left is living and still retains its spines,
whereas the other specimen is a skeleton that has been bleached.

These specimens are extremely thin and delicate.
Their ventral side (top)
is nearly flat, while the dorsal side (below) is slightly arched.