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.
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