young, 2.5 mm
young, 15 mm
probable egg mass
Pleurobranchus forskalii (Ruppell &
|Maximum size: about 200 mm
of this species is covered with broad, rounded compound
tubercles. The color is highly variable ranging from light golden-brown
with extensive white pigment to dark violet-brown (usually with white
arcs outlining the tubercles). In contrast, light animals often have
dark arcs outlining the tubercles and white pigment concentrated on
their dorsal faces. The underside of the foot is spotted with dark
pigment and the rhinophores of juveniles are tipped in white. Its shell lacks radiating striae.
is a moderately common nocturnal species. It can occasionally be found in
tide pools at moderately exposed rocky sites but is more frequently
seen in Halimeda kanaloana
beds at depths of 9-10 m (30-33 ft). It may also occur in shallow,
protected sandy habitats at depths of as little as 1 m (3 ft). It
usually carries the
posterior portion of its mantle in a siphon-like fold and may bury
itself in sand during the day. (Note 1) It probably feeds on colonial tunicates. (Note 2) It lays a large,
cream, spiral egg mass with a ruffled margin.
Big Island, Maui and Oahu: widely distributed in the Indo-Pacific.
first recorded in Hawaii from Hale'iwa Harbor, Oahu by Darrell
referred to as "Forsskal's pleurobranch" in Hoover, 1998 & 2006.
dark: Napili Bay, Maui; April 21, 2005.
Observations and comments:
1: Ralph Turre photographed an animal buried in sand except for a funnel-shaped fold of the foot margin. (see photo)
Perhaps, the exposed fold channels water over the gill of the buried
animal? During the 2017 MarineGeo at Kaneohe Bay, Oahu a mature animal
was found resting in a shallow sand patch with the notum lightly covered
On March 14, 2014 a 22 mm animal produced three strings of fecal
material while held in a dish. The material appeared to be largely
composed of "compressed" remnants of a white didemnid tunicate that is
common in the habitat where it was found (suggesting that it eats that
species). (see photo)