Thick-horned Nudibranch
Hermissenda crassicornis (Eschscholtz, 1831)
Description 2
Ground color translucent greyish-white. A median band of brilliant cadmium orange occurs between oral tentacles and passes between rhinophores (where it is narrowest), to anterior of cardiac region; an opalescent blue line occurs dorsally on either oral tentacle, becoming broader & bifurcating proximally, inner portion of blue line extends between rhinophores, on either side of orange line, and continues dorso-medially to tip of tail; outer portion of these blue lines extend dorso-laterally to tip of tail. A narrow, opalescent blue line extends posteriorly along dorsal margin of foot, from foot corners to tip of tail. Cerata in 5-11 groups, with reddish-orange tips, & a bluish-white band longitudinal on anterior surface of each ceras, cores usually light burnt umber to deep brown, but variable depending upon food source. Rhinophores weakly perfoliate, with about 10-14 lamellae, clavus opalescent white to very pale blue. Distinguished from Hermissenda opalescens which has cerata tipped with white, with a subterminal band of cadmium orange, & lacks a bluish-white longitudinal band on anterior surface of each ceras. May be distinguished from the much rarer Emarcusia morroensis which has smooth rhinophores and lacks opalescent blue lines on body.
Size 2
Typically about 25mmm in length, but may exceed 50mm.
Geographic Range 2
Kodiak Island, AK, to Monterey Bay, California.
Notes 2
Preys on a variety of hydroids.
References 2
LINDSAY, T., & Á. VALDÉS. 2016. The model organism Hermissenda crassicornis (Gastropoda: Heterobranchia) is a species complex. PLoS ONE 11(4): e0154265. PDF
MACFARLAND, F. M. 1966. Studies of opisthobranchiate mollusks of the Pacific coast of North America. Memoirs of the California Academy of Sciences 6:1-546, pls. 1-72. PDF
McDONALD, G. R. 1983. A review of the nudibranchs of the California coast. Malacologia 24(1-2):114-276. PDF
Synonyms 2
Phidiana crassicornis.
Additional Info 2
Sources and Credits
- (c) Gary McDonald, all rights reserved, uploaded by Gary McDonald
- (c) Gary McDonald, some rights reserved (CC BY-SA)
More Info
iNat Map
| Body | aeolidiform |
|---|---|
| Cerata | unbranched |
