with food sponge
in tide pool
Asteronotus cespitosus (van Hasselt,
|Maximum size: about 250 mm.
This is a large mound-shaped dorid with a distinctive sculpted
appearance. The notum is smooth with large raised ridges and tubercles.
There is usually a mid-dorsal longitudinal ridge flanked by compound
often rough "mirror images" on either side. The tubercles become
smaller marginally. The margin is thin and translucent, sometimes edged
in pink. The color varies from light yellow to caramel
to grayish tan with the tubercles and rhinophores a light cream or pale
yellow. Rarely, the notum may be gray. (Note 1) Its gills appear to change from light tan during the day to
chocolate brown or
blood red at night.
moderately common dorid found in protected to highly exposed rocky
areas. It has been
found in tide pools and subtidally to 17 m (55 ft). It is typically
active at night but it may rest in
the open during the day.
Occasionally, the commensal shrimp, Zenopontonia rex (= Periclimenes imperator), lives on this nudibranch. Compounds characteristic of
the blue-gray sponge Dysidea herbacea
have been isolated from A. cespitosus
suggesting that it feeds on that species. (Fahey & Garson, 2002)
Big Island, Maui, Molokai, Oahu, Kauai and French Frigate Shoals (also Johnston Atoll?); widely
The name means "forming dense clumps," in reference to the large groups
of tubercles on the notum. It is referred to as the "clumpy nudibranch"
in Hoover, 1998 & 2006. It was probably first reported from Hawaii
1860 (as Doris foetida).
Photo: PF: 93
mm: Kamaole, Maui; Dec. 15, 2006.
Observations and comments:
1: The large, gray animal photographed by Mike Rudenko is probably a rare
color form of this species. However, the DNA should probably be checked
for confirmation. Only the notum is gray with the rhinophores and gills
having "normal" pigmentation. Meanwhile, the morphology is comparable to
other animals. Gray animals have also been photographed elsewhere in
the Indo-Pacific. The animal had a wound in its notum (fish bite?) but that is probably unrelated to the color since gray animals from elsewhere lacked wounds. (see photo)