Cerberilla sp. #1
|Maximum size: 15 mm.
with long cephalic tentacles and a
broad foot. The cerata are stained with brown and have narrow, yellow
medial bands. The head has dark brown bands and a patch of yellow
between the cephalic tentacles. Unlike in Cerberilla albopunctata,
the rhinophores remain light at all
sizes, the cephalic tentacles and sides lack well-defined white spots
there may be a few white flecks on the cephalic tentacles),
yellow bars in front of the rhinophores are absent (or
faint), posterior cerata lack brown
tips and there are yellow bands on all or most of the ventral cerata.
Though older animals may develop some mottling on the notum, it's far
less extensive than in C. albopunctata and the center of the notum is
largely obscured by cerata, anteriorly. (Note 1)
Cerberilla spp., Cerberilla
sp. #1 appears to be a nocturnal
feeder. We've observed it on a number of occasions foraging at night in
holding dishes with its cephalic tentacles extended to the side. It
buried itself in sand in the bottom of the dishes during the day. We
also seen it actively crawling in the field at night. However, others
have seen numerous animals crawling in the open by day suggesting that
it also feeds (or mates?), then. (Note 2) It's a moderately common species that can be
found in protected, back-reef sand patches at depths of about 1 m (3
ft) as well as in Halimeda kanaloana
beds at depths of 6-11 m (20-36 ft). It feeds on a small ceriantharian anemone (probably Arachnanthus sp.) and lays a white, corkscrew-shaped egg mass that is anchored in sand. (Note 3) The
eggs hatch in about five days in the laboratory.
Big Island and Maui: may also be known from French Polynesia.
Taxonomic notes: It was first
from Hekili Point, Maui by CP on Nov. 1,
Hekili Point, Maui; Nov. 19, 2002.
Observations and comments:
1: The yellow pigment on the head and cerata shows strong green fluoresces under UV light. (see photo)
Since this species is nocturnally active, the florescence might contribute to its pattern of
camouflage under specific conditions (strong moonlight? dusk/dawn?) Or,
it might be a neutral characteristic that is coincident to a pigment
deposited for some other reason...
Rebecca Bicker reported seeing numerous animals crawling on open sand
day at Maalaea Bay. Kevin Roe, Mike Ryan and others have also seen
them at the site. Perhaps, there is something unique to the
area that favors diurnal activity? Or, perhaps the daytime sightings
represent a mating aggregation? Most animals photographed by day were in
all ways comparable to those seen at night.
Katherine Shepherd observed one feeding on a small ceriantharian
anemone. She reported that "The slug, at first, recoiled from touching
the anemone, but then quickly attacked! It eventually disappeared down
the tube." Since Katherine observed it completely disappearing down the
anemone's tube following the attack, perhaps it more fully consumes it
than "one bite and move on" predators like Dermatobranchus rubidus? (see photos)