young, 3 mm
Cyerce elegans Bergh, 1870
|Maximum size: 40 mm.
species is translucent cream to dusky brown. (Note
1) The broad, pillow-like cerata are edged with cream flecks and
often show an iridescent internal green spot under some lighting
conditions. Rarely, it may have narrow dark lines on the
margins of its cerata. (see photo) When examined closely, the cerata are usually
divided into sections
by a network of transparent vein-like lines. However, some animals,
juveniles, may lack visible lines.
Cyerce elegans is
a common species found in Halimeda
kanaloana beds at depths of 10-27 m (33-90 ft). On Maui it only
rarely occurs in rocky habitats at depths of 4-5 m (13-16 ft). However,
on Oahu, it may occasionally be common in protected rocky areas at depths
of as little as 1-2 m (3-6 ft) occurring in association with other
species of Halimeda. It's nocturnal
but may be found under pieces of rubble/debris or nestled at the bases
of the alga during the day, often in pairs or clusters. (Note 2) We've observed it feeding on Halimeda kanaloana and Halimeda discoidea in dishes. (Note 3) It
lays a cream, spiral egg mass (usually on its host alga) and the eggs
hatch in about seven days in the laboratory. On June 1, 2013 at least one was observed being attacked by a saddle wrasse (Thalassoma duperrey) when exposed by rock turning.
Big Island, Maui and Oahu: widely distributed in the Indo-Pacific.
Taxonomic notes: It's listed as Cyerce cf. elegans in Kay & Schoenberg-Dole, 1991 and may have been first reported from Hawaii in Kay, 1979.
Photo: CP: 14
mm; dark: Airport Beach, Maui; April 2, 2003.
Observations and comments:
1: An animal found on Oct. 25, 1997
was held in an aerated, lidded bucket without food for six days. Over
that period, it changed from translucent cream to dusky brown
a frosting of minute brown flecks. A second animal found on Nov. 18,
1997 and held under similar conditions showed a comparable change.
Whether they were responding to darkness, lack of food or something
else hasn't been determined. Other animals held with food and light
haven't shown a similar change.
Note 2: When resting
motionlessly at the base of its host alga, this species appears very
similar to a small clump of a species of red alga (Martensia fragilis?) that
frequently grows on the bases of the Halimeda
and has blades similar in size to the cerata of the Cyerce (see photo). Perhaps, it gains some
protection from predators by mimicking it?
Note 3: A young animal
from Nov. 3, 2004 till Dec. 6, 2004 grew from 3 mm to 5 mm. However, it
was fed primarily on Halimeda
discoidea, perhaps a less than optimum diet since it's usually
associated with H. kanaloana.