young, 1.5 mm
Aplysia elongata (Pease 1860)
|Maximum size: 40 mm.
hare varies from light cream flecked with white to velvet
black. (Note 1) Rarely, it may have a reddish tinge. (Note 2) The edges of the parapodia,
rhinophores and cephalic tentacles are powder-blue. The shell is
usually visible between the parapodia and there is a distinctive brown
line crossing the protoconch.
common species found in rocky habitats and Halimeda kanaloana beds from < 1
to 23 m (< 3 to 75 ft). It occurs at protected to highly exposed
sites. Small animals seem to be primarily nocturnal. However, larger
animals appear to be primarily diurnal with all or most mating
occurring by day. When populations are high, mating pairs are commonly
seen on top of coral rubble or algae and they sometimes form mating
chains of up to half a
dozen animals. This appears to be particularly true when they are on or
near a red algae tentatively identified as Laurencia nidifica. (Note 3) They eject a purple dye when disturbed and
lay a tangled, greenish-brown egg mass. The eggs hatch in about seven
days in the laboratory.
Big Island, Maui, Oahu, Kauai, Niihau, French Frigate Shoals, Midway and Kure. (Note 4)
to as the "small sea hare" in Hoover, 1998 & 2006. It
was first reported from Hawaii in Pease, 1860 (as Syphonata elongata) and is listed as Tethys elongata in Edmondson, 1946, Ostergaard, 1950 and Ostergaard, 1955. It's listed as Aplysia parvula in Kay, 1979, Johnson, 1982, Kay & Schoenberg-Dole, 1991, Hoover, 1998, Hoover, 2006 and many other sources.
Photo: CP: 40
mm; mottled: Hekili Point,
Maui; March 21, 2005.
Observations and comments:
1: On Oct. 25, 1997 a velvet-black
and light animal were observed copulating in a dish. Also, dark and
light mottled animals were seen paired in the field on April 10, 2008
(and on other occasions).
This supports lumping the various color forms under one species.
There is some possibility that the reddish animals might represent a
second Hawaiian species since the color form is more common in Japan.
Note 3: Over the years,
diurnal activity and mating have been observed many times in large
animals living on patches of Laurencia
nidifica(?) near the reef crest at Hekili Point. Although not
confined to that substrate, the behavior
seems more common there than in other locations. Perhaps,
activity patterns are altered by the amount of defensive compounds
retained from their food?
Golestani, et. al. (2019) recovered the Hawaiian population of what was
formerly considered to be the widely distributed species, Aplysia parvula, as an endemic.