Xiphister atropurpureus
FAMILY
Stichaeidae
TAXONOMY
Ophidium atropurpureum Kittlitz, 1858, Alaska (no specifics). Correct generic placement should probably be in Xiphidion Girard, 1858 (or 1859), pending further research.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
Body eel-like. Pectoral fins are minute, of only 11 or 12 rays. Pelvic fins absent. Dorsal and anal fins continuous with caudal, which is well developed and has a whitish band at its base. Color reddish brown to black; abdomen is lighter. Head has three broad, black eye bars with whitish borders. Scales are minute, rounded, and covered with skin.
DISTRIBUTION
Kodiak Island, Alaska south to Baja California Norte, Mexico.
HABITAT
Intertidal zone in rock pools among seaweeds and in crevices out to about 32.8 ft (10 m). Also found under wharf pilings and in boat harbors where shelter (human trash usually) can be found.
BEHAVIOR
Solitary and cryptic without territoriality. Parental care of the eggs occurs (see below).
FEEDING ECOLOGY AND DIET
Omnivore. Feeds on seaweeds and invertebrates on or associated with the bottom, primarily crustaceans, worms, and sea
snails. Hatchlings caught in surface-towed nets in British Columbia had been feeding on copepod crustaceans and clam larvae but probably eat any small planktonic animals.
REPRODUCTIVE BIOLOGY
Spawning occurs from winter to spring throughout the range, under rocks along protected pebbly or shelly beaches in winter and shifting to other beaches that are more exposed in spring. Females lay about 900–1,700 eggs about 0.1 in (2 mm) in diameter, and males guard the site. Males may spawn with more than one female. Territoriality is non-existent in that several males may congregate under the same rock, and sometimes other species, such as clingfishes, are found nearby. Hatchlings are about 0.3 in (8.5 mm) long, and metamorphosis occurs at about 0.7 in (18 mm) when they become free-swimming and feed on small plankton.
CONSERVATION STATUS
Not threatened. Common and widespread along its extensive range. It is cryptic and rarely encountered by either humans or predators.
SIGNIFICANCE TO HUMANS
Owing to its secretive habits and small size there has never been a fishery for the black prickleback, and it does not make a good aquarium fish; thus the species has been of little significance to humans.
