small blue spots
large cream spots
young, 7 mm
Miamira sinuata (van Hasselt, 1824)
|Maximum size: 53 mm.
Hawaii, this species has a bright green body with yellow to orange
spots. Irregular bright blue spots, sometimes ringed in brown,
encircle the notum just inside the mantle edge.
(Note 1) The greenish rhinophores and translucent tan gills are finely
flecked with white. An unusual characteristic of this species is the
tri-lobed anterior end of the mantle, with the middle lobe longer than
the other two, almost giving it the appearance of having a “nose.”
Natural history: Miamira sinuata is rarely seen in Hawaii. It has been
tide pools and down to a depth of 27 m (88 ft) in moderately exposed to
exposed rocky habitats.
Elsewhere in the
Pacific, it has been found in association with sponges of the genus Dysidea (Gosliner,
et. al., 1996). The anterior and lateral mantle lobes may contain
that produce chemicals known to repel predators. It feeds on a gray-violet sponge, perhaps in the genus Dysidea.
Big Island, Maui, Molokai, Oahu and Midway: widely distributed in the
purple/brown color form found elsewhere in the Pacific has not been
seen in Hawaii and some Hawaiian animals have larger blue spots
than most M. sinuata found
in other regions. That provides some support for the hypothesis that
the Hawaiian population may be
genetically distinct. It is listed in Bertsch and Johnson, 1981 as
"jolly green giant" and was first recorded in Hawaii from Waialua, Oahu
Scott Johnson on June 10, 1978. It's listed as Ceratosoma sinuata
and referred to as the "jolly
green giant" in Hoover, 1998 & 2006 (corrected in 2019 printing). The presence of two distinct
types of blue spotting in the Indo-Pacific population suggests that the
species might be split in the future (only one is present in Hawaii).
Napili Bay, Maui; May 1, 2003.
Observations and comments:
1: The blue spots on a gold background aren't as precisely matched to the blue and gold ocelli found in the sea hares Stylocheilus
striatus and Phycophila euchlora as are the markings in some other possible mimics.
But, perhaps they are close enough so that M. sinuata is
still deriving some benefit from the resemblance (since the sea hares
are known to concentrate toxins from the cyanobacteria they eat)?