FAO Species Identification Guide for Fishery Purposes Western

816 Cephalopods
Octopus nocturnus Norman and Sweeney, 1997
Frequent synonyms / misidentifications: None / Octopus
macropus Risso, 1826.
FAO names: En - Philippine night octopus.
Diagnostic characters: Moderate-sized octopus. Arms long, 5 to
6.5 times mantle length. Dorsal arms distinctly longer than other
arms (arm formula I.II.III.IV). Webs shallow, deepest 10 to 15% of
longest arm. Right third arm of males hectocotylized with moderate
length ligula (3 to 5% of arm length). Gills with 10 or 11 lamellae per
demibranch. In larger specimens, 180 to 220 suckers on each normal
arm, 80 to 90 on hectocotylized arm of male. No enlarged suckers
in either sex. Eggs small type and numerous (more than 1 000) in
submature females examined. Colour: pattern of red-brown base
with irregular darker blotches and white spots over dorsal surfaces
including mantle; white spots paired along length of arms;
skin sculpture of small low round papillae; no primary papillae visible.
Size: Maximum mantle length around 60 mm,
total length to around 350 mm; weight to at
least 100 g.
Habitat, biology, and fisheries: Known primarily
from intertidal coral and rocky reefs.
Deepest record a poison station affecting between
a depth of 1.5 and 4.5 m. Members of
this species emerge at night to forage during
low tides on intertidal reefs. Females produce
small eggs in large numbers. Collected in local
subsistence harvest, speared on night low
tides, historically using burning bamboo
torches to find active octopuses.
Distribution: At this stage, known only from
throughout the Philippines.
tip of hectocotylized
arm of male
dorsal view