young, 5.5 mm
Dolabella auricularia (Lightfoot, 1786)
|Maximum size: about 300 mm. (Note 1)
one of the largest opisthobranchs in Hawaii. The body is
wedge-shaped with a small head and a broad, flattened posterior disk.
The parapodia are fused except for circular apertures anterior to and
in the center of the disk. The surface is intricately tuberculate. The
color is highly variable ranging from dark brown through mottled brown
and green to whitish. (Note 2)
is a common species found in mixed habitats and rocky areas both in
tide pools and subtidally at depths of < 1 to 21 m (< 3 to 70
It occurs in highly protected to moderately exposed locations. It's
nocturnal, concealing itself in crevices or under rocks during the day.
When disturbed, it ejects purple dye through the aperture in the center
of the posterior disk. (Note 3) It lays a
tangled, spaghetti-like egg mass similar in appearance to the egg
masses of Aplysia spp. Because of its large size, dead animals are occasionally found on beaches. (see photo) (Note 4)
Big Island, Maui, Molokai, Oahu, Kauai, Niihau, French Frigate Shoals and
Midway (also Johnston Atoll):
distributed in the
Indo-Pacific; also in the eastern Pacific.
to as the "eared sea hare" in Hoover, 1998 & 2006. It
was first reported from Hawaii in Pease, 1860 (as Dolabella variegata)
and is listed under that name in Edmondson, 1946 and Ostergaard, 1955.
There's some chance that the "small tubercles" form could prove distinct with
Photo: CP: light: Honokohau Harbor, Big Island; Nov. 19, 2011.
Observations and comments:
Note 1: An unmeasured animal seen by CP at Mala Wharf may have approached 350 mm.
Note 2: We've seen light and dark
animals copulating in the field.
Note 3: On several
occasions, we've observed an animal responding to a flashlight beam by
crawling into a crevice and flattening out its posterior disk to block
the entrance. (see photo) When prodded, they ejected dye from the aperture in the
center of the disk. Presumably, this might discourage pursuing
Note 4: On at least three occasions we've
observed Dolabella auricularia
by other animals during the day. On Aug. 21, 1989 a bigeye emperor (Monotaxis grandocularis)
spotted one on the bottom and went down to pick it up. It
appeared very chewy and it took the emperor several minutes to eat it. All the
while, purple ink was pouring out of its mouth. On May 25, 2015 about
five emperors were observed competing for the body of another animal. On
March 15, 1990 we
observed a banded spiny lobster (Panulirus marginatus) holding and
eating the remains of one. Autumn Hill also observed a banded spiny lobster feeding on the remains of one on April 4, 2015. (see photos) Twice, we've seen animals with chunks
bitten out of them near stripebelly puffers (Arothron hispidus) suggesting that
it also preys on the species.