Hallaxa cryptica is a relatively common species at Kwajalein and Enewetak Atolls. Size ranges to at least 30mm in length.
Most specimens are found under rocks on shallow lagoon pinnacle reefs with the animals almost invariably on their food sponge, which they closely resemble.
The specimen immediately below is a bit different with the presence of translucent grayish windows crowded together on the dorsum, similar to those of H. translucens and H. paulinae. This one may not really be H. cryptica.
Color is usually the cream to light tan colors as shown above, but occasionally specimens feeding on a purple variety of the same sponge take on purple coloration, both in their bodies and in their egg masses, a little bit of which is seen in the lower part and upper left corner of the photo below.
The purple specimen in the two photos below was found under a rock at a depth of about 6m on a Kwajalein Atoll lagoon reef on 21 June 2009. In the first photo, captured from video, it was eating the brownish sponge it is on.
The specimen below was one of the largest ones seen. It was not measured, but must have been close to 40mm. There is a small individual nestled up against the big one. The large one had a curious crater-like ridge surrounding its gills. We have not ever seen that before. The egg mass in the following photo was under the same rock and likely belonged to this large Hallaxa.
Created 15 December 2006
Updated 18 July 2009
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