young, 10 mm
eye stalk detail
Onchidium verruculatum (Cuvier, 1830)
|Maximum size: about 35 mm.
This is a grayish-black slug-like animal with a dorsal surface covered
by variably sized tubercles. They resemble land slugs in that their
eyes are on the tips of stalks.
is a common species in the high intertidal on rocky shorelines
and on overhanging kiawi branches. It probably does most of its feeding
at night while exposed during low tides and appears to graze on
microalgae. (Note 1)
Big Island, Maui, Oahu and Kauai.
It's listed as Peronia sp. in Edmondson, 1946 and referred to as the "warty slug" in Hoover, 1998 & 2006.
about 35 mm: Hekili Point, Maui; Nov. 19, 2007.
Observations and comments:
1: Although Kay (1979) states that it feeds on the red algae Ahnfeltia, we haven't been able to confirm the observation.