TAXONOMY
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Tetraodontiformes (Puffers and filefishes)
Family: Balistidae (Triggerfishes)
Genus/species: Xanthichthys auromarginatus
Male below
GENERAL CHARACTERISTICS: Steel blue with white spots. Males have blue chin patch and yellow margins on dorsal, anal, and caudal fins. Females lack chin patch, and have maroon stripe on base of dorsal and anal fins, and on outer margin of tail.
Their scales are plate-like and have no pelvic fins.
Length to up to 11.8 inches. (male above, female below)
DISTRIBUTION/HABITAT: Indo-Pacific: East Africa to Hawaiian Islands, north to the Ryukyus, south to New Caledonia. Marine reefs 25 – 450 ft depths.
DIET IN THE WILD: Feeds a few meters above the bottom where it consumes zooplankton (prefers copepods).
REPRODUCTION: Distinct pairing, oviparous, external fertilization.
REMARKS: The common name comes a unique interaction between the large first dorsal spine and the smaller second one behind. When the posterior spine is erect, it locks the strong first spine vertically in place, allowing it to wedge itself into a protective space, perhaps a hole or under a rock, where a predator can rarely extract it. When the posterior spine is depressed, the anterior spine folds back easily, like taking a lock off a trigger.
Pink tail triggerfish with trigger erect below (not on exhibit)
Halfmoon trigger hiding below (not on exhibit)
Like all triggerfishes, able to rotate eyeballs independently.
References
California Academy of Sciences Philippine coral reef 2016
Ron’s flickr www.flickr.com/photos/cas_docents/2978997545/edit-details/
Ron’s Wordpress shortlink http://wp.me/p1DZ4b-RX
fishbase www.fishbase.us/summary/6030
Ron's Critter of the Day 