Octopus rubescens Berry,
1953
Common name(s): Red octopus
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Synonyms:
Octopus pricei |
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Phylum
Mollusca
Class
Cephalopoda
Order Octopoda
Family Octopodidae |
Octopus rubescens from intertidal,
San Simeon, Ca |
(Photo by: Dave Cowles May
1997). Caution:
This species often bites! |
Description: This
small octopus (8 arms,
no fins on body, no internal "pen" skeleton) has skins with papillae;
white spots on the dorsal mantle
and on the web in front of the eyes but no large "ocelli"
spots.
Arms 3-5 times the body length. The mantle
length is usually less than 10 cm.
How to Distinguish from
Similar Species: Enteroctopus
dofleini is larger (also red), male has a larger hectocotylus
(about 1/5 the length of the arm vs 1/10 for O. rubescens
(photo)),
and its skin has abundant wrinkles along with the papillae.
It is
also said that Enteroctopus
dofleini
does not have the three cirri
that are found below the eyes of O. rubescens (photo).
Geographical Range: Alaska
to Scammon's
Lagoon, Baja California and in Gulf of California. Most
common intertidally
in the southern part of the range. The commonest small
intertidal
octopus in some areas (especially northern California) but in
Washington
E.
dofleini seems more common.
Depth Range: Intertidal
to 200 m.
Habitat: Kelp
beds (juveniles often washed
ashore in kelp holdfasts), rocky areas, sandy mud bottoms, under stones
on low intertidal.
Biology/Natural History:
The sixth pair
of suckers is enlarged on all but the ventral arm of males.
Male
hectocotylus
is conspicuous, about 1/10 the length of the 3rd right arm, where it is
located (photo).
The ink is reddish or
red-brown. The larvae have a double row of chromatophores
on each arm (E.
dofleini
has only 1 row/arm). Adults eat crustaceans, mollusks, and
fishes.
They especially seem to prefer to eat small crabs and hermit
crabs.
Females guard egg clusters intertidally or shallow subtidally from late
spring through early winter in rocky areas. Peaks in breeding
are
in August and September. Young hatch in 6-8 weeks, spend a
brief
period in the plankton, and settle as juveniles in the kelp
beds.
Larger individuals migrate farther offshore on sandy mud
bottoms.
They mate in deep water in late spring, then move inshore
again.
They ae often found in prawn traps.
References:
Dichotomous Keys:
Jorgensen,
2009
Kozloff
1987, 1996
Scott
and Blake, 1998
Smith
and Carlton, 1975
General References:
Gotshall,
1994
Harbo,
1999
Kozloff,
1993
Morris
et al., 1980
Norris, 2003
Niesen,
1994
Ricketts
et al., 1985
Scientific Articles:
Anderson, RC., P. D. Hughes, J.A. Mather, and C.W. Steele,
1999.
Determination of the diet of Octopus rubescens
through examination
of its beer bottle dens in Puget Sound. Malacologia 41:
455-460
Anderson, Roland C. and Eliza A.H. Little, 2006.
Observations
of a brooding Octopus rubescens (Cephalopoda:
Octopodidae).
The Festivus 38:1 pp 10-12 (San Diego Shell Club)
Hochberg, F.G., 1998. Class
Cephalopoda:
Taxonomic Atlas
of the Benthic Fauna of the Santa Maria Basin and the Western Santa
Barbara
Channel. Volume 8 part 1: The Aplacophora, Polyplacophora,
Scaphopoda,
Bivalvia and Cephalopoda, pp. 1-250. P.V. Scott and J.A.
Blake, Editors.
Santa Barbara Museum of Natural History, Santa Barbara, CA, USA
Mather, J.A. and R.C. Anderson, 1993. Personalities of
octopuses
(Octopus rubescens). J. Comparative
Psychology 107:3 pp 336-340
Student Projects:
Thomas, Jeremy and Lyndsi Hersey, 2006. Remote chemosensory
and
feeding in Octopus rubescens near Deception Pass,
Washington.
Jeremy and Lyndsi tested whether this species would use its
chemosensory
powers to respond to the smell of prey. Using two different
red individuals,
they repeateadly placed either two clear plastic tubes or two opaque
plastic
tubes into their aquaria, then placed a crab into one of the tubes
while
out of sight of the octopus. The water inlet was flowing
through
the tubes so that the smell of the prey should enter the
water. They
observed the octopus' behavior for 20 minutes after placing the prey in
the tube. The showed little special interest in the opaque
tubes.
They occasionally contacted the tubes or even climbed on top of them
and
reached their arms partly inside, but never encountered or captured the
prey. On several occasions the octopus actually entered a
tube but
it happened to be the empty one. With the clear tube (through
which
they could see the prey) the octopus several times quickly swam to the
tube and embraced it, but could not seem to figure out that they had to
go to the end of the tube to capture the prey. More often
they would
ignore the prey, which was standing mostly immobile at the bottom of
the
tube, even though the prey was clearly visible to them. As
soon as
prey were released free into the tank, the octopus quickly captured
them.
The students concluded that this species does not seem to use smell to
find prey, but need to see the prey moving and/or actually touch the
prey
in order to be stimulated to capture it.
General Notes and
Observations: Locations, abundances,
unusual behaviors:
I have seen this species swimming at about 500 m depth in
Monterey Bay
in late spring (observations using the MBARI Ventana ROV).
Presumably
these individuals were adults which had swum out to deep water to
breed.
This individual is trying to sneak away through the intertidal
algae.
Dave Cowles, San Simeon, CA 1997
This individual has about a 20 cm arm spread. Captured near
Rosario.
This individual is a male. It usually keeps its hectocotylus
arm coiled, as can be seen on the
left in this view. The hectocotylus
arm is the third arm on the animal's right side. The first
and second
arms on the right are straight and the third arm is coiled in this
view.
Photo by Dave Cowles, June 2006
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Photo by Dave Cowles, July 2006 |
Photo by Kirt Onthank, April 2007 |
Photo by Kirt Onthank, April 2007 |
It is said that one way to
distinguish Octopus rubescens
from small Enteroctopus
dofleini
is that O. rubescens has three distinct cirri
below the eye, as seen in these views. |
In this photo, the same individual shown in the tank above has eaten
an oregon cancer crab Cancer
oregonensis which was nestling within the plates of
a dead barnacle,
then took over the barnacle. Notice the mottled camouflage
appearance
and the three cirri clearly visible below the eye.
This photo shows a female Octopus rubescens (right
and bottom)
tending her eggs (center) which she has laid inside a beer bottle.
The bottle is encrusted with barnacles and tubeworms. Photo
by
Kirt Onthank, 2007.
The beak of an Octopus rubescens adult is about 1
cm long.
This is the beak of the brooding female from the picture above, which
died after brooding her eggs for 3 months.
Many of the eggs had become cloudy and did not appear viable after
the 3 months.
Photo by Kirt Onthank, March 2007
Authors and Editors of Page:
Dave Cowles (2005): Created original page
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