Identifying Commonly Kept Octopuses

I. Acquisition

A. Sources

1.Captive Raised

a)Tank Bred
Aquarium Mated Female

(1)Labs/Aquariums

(2)Hobbyists (very rare)

(a)O. Mercatoris most successful

b)WC Mated Female
WC Female Mated Before Capture

(1)Hobbyists

(2)School Aquariums

2. Wild Caught

a)Catch Your Own

b)Fish Collectors

(1)By-Catch Crab or Lobster Fishermen

(2)By-Catch Live Rock

(3)Occasional Direct Catch

c)LFS

(1)Usually purchased through wholesaler

d)Food Market

3.Pros and Cons

a)Captive Raised

(1)Known Species (usually)

(2)Known Age

(3)Full complement of arms

(4)Only viable for large egg species

(5)Very shy until 4-5 mMonths old

(6)Tank mating risks female killing male

(7)High hatchling mortality rate

(a)In situ survival rate is estimated at 1%

(8)Rarely, if ever available for purchase

b)Wild Caught

(1)Unknown Species

(2)Unknown Age

(3)Missing Arms

(4)Female May Brood Shortly After Introduction to the Aquarium

(a)Possibly an easy captured because she was foraging to prepare for brooding

(b)Eggs will likely be fertile

(c)Females will brood and produce eggs even if they have not mated

(d)It is possible but difficult to raise a few hatchlings from large egg species

 

 

II. If an Octopus is Labeled ...
      It MIGHT be ...

A.Bali/Indonesian

1.Abdopus (Indonesia)

a)aculeatus

b)other (usually smaller) in Abdopus complex

2.Macropus ?(Indonesia)

B. Bimac/Two-Spot

1.O. bimaculoides (Pacific intertidal)

2.O. bimaculatus (Pacific deep water)

3.O. hummelincki (Caribbean/Haiti)

C. Brown Octopus

1.O. hummelincki

2.Macropus ? (Indonesia/Philippines)

3.O. vulgaris (anywhere)

4.O. bimaculoides/bimaculatus (Pacific)

5.O. joubini (Caribbean/Atlantic)

6.Probably NOT O. briareus (Caribbean)

D.Common Octopus

1.O. vulgaris (anywhere)

2.O. briareus (Caribbean)

3.O. mercatoris (Caribbean)

E. Joubini

1.O. joubini (Caribbean)

2.O. mercatoris (Caribbean)

F. Red Octopus

1.O. mercatoris (Caribbean)

2.Macropus (Indonesia)

3.O. rubescens (Pacific)

 

 

III. IdentifyingTraits

A. Legs
Cephalopods have Arms and Tentacles
Not Legs but...

1.Recent observations suggest Octopus Arms L3,L4,R3,R4 may be used more as legs than arms

2.The Flamboyant cuttlefish rarely swims. It and others and have modified arms use to walk along the bottom

B. Tentacles
Octopuses have Arms Not Tentacles. Tentacles have No Suckers Along the Length but May have Multiple rows of Suckers on a Terminating Club

1.Nautilus
60+ suckerless tentacles

2.Cuttlefish
Two Tentacles - Eight Arms

a)None in Western Hemisphere

b)The Atlantic Caribbean Reef Squid(Sepioteuthis sepioidea) is often mistaken for a Western cuttlefish

3.Squid
Two Tentacles - Eight Arms

a)Squid arm suckers may include a ring of chitinous teeth

b)Squid tentacle incorporate chitinous hooks

c)Some deepwater species are difficult to classify as either Squid or octopodes

d)Taningia danae (and others in the Octopoteuthidae family) lose their tentacles as adults

C. Arms
Octopuses have 8 Arms with Suckers Along the Length

1.Identification Clues

a)Arm proportional length and Thickness

b)Color around the base of the suckers

c)Row Count and Position of Suckers

d)Webbing Depth

e)False Eye Spots (Ocelli)

2.Sexing Aid

a)Specialized Arm R3(Hectocotylus)in Males has spermataphore channel and suckerless tip(ligula)

b)Males often have enlarged suckers on two to four front arms

D. Mantle
Behind the eyes to the Tip of the Sack
Contains the Organs

1.Identification Clues

b)Ratio to Arms

c)Ratio length to width

2.Aging Aid

a)Length

a)firmness and muscle control

E.Head
Eyes to Mouth

1.Identification Clues

a)Eyes proportional size to mantle

(1)Proportionately large eyes suggest nocturnal

b)Thickness of join to Mantle

c)Eye Stalk Height

(1)Eyes may always sit close to the mantle or can be raised

(2)Long eye stalks suggest sand burying animal

F. Crypsis (Camouflaging Ability)

1.Skin Texture(Papillea,Cirri)

2.Color Variations

3.Distinct Patterns

a)exotics more distinct than on common species

G. Displays That Don't Identify

1.Cone Head

2.Color White

3.Skunk Stripe

 

 

IV. Commonly Available Species

A. Abdopus aculeatus
    (d'Orbigny 1834)

1. Common Names

a)Bali Octopus

b)A smaller, nocturnal animal in the Abdopus complex is often misidentified as a young aculeatus

2. Size

a)Min Tank: 45+ gallons (needs roaming room)

b)Mantle: 6 cm (~2.5")

c)Arms: 30 cm (~12")

3. Attributes

a)Origination: Indonesia/Philippines/Australia

(1)Warm water species (75-80 deg F)

b)Most active: Daytime (diurnal)

c)Egg Size: Small

d)Can discard an arm near the base

4. Identification

a)Arms

(1)Sucker Ring Color: Blue/Purple

(2)Webbing: Shallow-Medium extends full arm length

(3)Differences: L2,R2 Longest and Thickest (size may be impacted by regrowth)

b)Mantle and Head

(1)Arm:Mantle Ratio: 5:1

(2)Eyes: ~1/5 mantle size, often shows horns

(3)EyeStalk: Distinct, gives neck like appearance between eyes and webbing

(a)Often seen with stalk extended and a branching horn above each eye

c)Crypsis

(1)Patterns: Mottled shades of brown, tan and white. Brown with white circles

(2)Color Range: Tan - dark brown

(3)Texture: Branching Papillea/Cirri

(3)Camouflage: Immitates floating seaweed using heavy texture changes

B. Octopus bimaculoides
    (Pickford & McConnaughey, 1949)

1. Common Names

a)Bimac

b)Two-Spot/California Two-Spot

2. Size

a)Min Tank: 55+ gallons

b)Mantle: 12 cm (~4.5")

c)Arms: 35 cm (~14")

3. Attributes

a)Origination: Mid-California to Baja, MX

(1)Cold water species (65-70 deg F) commonly kept

b)Most active: Daytime (diurnal)

c)Egg Size: Large

(1)Hatchlings successfully raised from WC female

4. Identification

a)Arms

(1)Sucker Ring Color: Orange/Peach

(2)Webbing: Shallow-Medium extends full arm length

(3)Ocelli: Concentric circles Yellow and Black. Black disk contains blue chain link circular pattern

b)Mantle and Head

(1)Arm:Mantle Ratio: 3:1

(2)Eyes: ~1/5 mantle size

(3)EyeStalk: Short with white diamond marking between the eyes

c)Crypsis

(1)Patterns: Splotchy circles with brI-Ght orange/yellow central spots

(2)Color Range: Tan - dark brown

(3)Texture: Papillea/Cirri are sparse, thick, singular pointed spikes

(d)Skin has a slimy look and feel

(3)Camouflage: Color and texture matching on live rock

C. Octopus briareus
    (Robson, 1929)

1. Common Names

a)Common Caribbean Octopus (CCO)

b)Common Octopus (gets confused with vulgaris)

c)Caribbean Reef Octopus

d)Briar Octopus

2. Size

a)Min Tank: 60+ gallons

b)Mantle: 12 cm (~4.5")

c)Arms: 60 cm (~24")

3. Attributes

a)Origination: Caribbean

(1)Warm water species (75-80 deg F)

b)Most active: Early AM, Early PM (crepuscalar)

(1) Adults often out in daylight

(2) Juveniles almost exclusively nocturnal

c)Egg Size: Large

(a)Limited tank raising success

d)Largest common octopus for tanks under 150 gallons

4. Identification

a)Arms

(1)Differences: L2,L3,R2,R3 Longest and Thickest (size may be impacted by regrowth)

(2)Sucker Ring Color: Orange/Peach

(3)Webbing: very deep with dramatic webover displays

b)Mantle and Head

(1)Arm:Mantle Ratio: 5:1

(2)Eyes: ~1/6 mantle size

(3)EyeStalk: Short

c)Crypsis

(1)Patterns: Mottled Peach and white, Brown mantle white arms, White with Green iridesecent spots

(2)Color Range: White, Peach, Irridescent Green, Brown - Rarely fully brown

(3)Texture: Papillea/Cirri small texture bumps giving almost fury appearance

(4)Camouflage: Papillea/Cirri small texture bumps giving almost fury appearance

D. Octopus hummelincki
    (Adam 1936)

1. Common Names

a)Caribbean Two-Spot

b)Bumble Bee

c)Filosus (older species name)

d)Often mislabeled

1)Bimac

2)Vulgaris

2. Size

a)Min Tank: 45+ gallons

b)Mantle: 7 cm (~3")

c)Arms: 30 cm (~12")

d)Size exceptionally variable

3. Attributes

a)Origination: Caribbean/Haiti

(1)Warm water species (72-80 deg F)

b)Most active: Daytime (diurnal)

c)Egg Size: Small

4. Identification

a)Arms

(1)Sucker Ring Color: Blue/Purple

(2)Webbing: Medium depth about 1/3 the arm length

(3)Ocelli: Concentric circles Yellow/Orange,Black. Black disk contains blue circular pattern with spokes and irregular holes,Yellow center dot. Yellow outer circle may show as dotted ring or not at all.

b)Mantle and Head

(1)Arm:Mantle Ratio: 5:1

(2)Eyes: ~1/5 mantle size

(3)EyeStalk: Short almost no neck appearance

c)Crypsis

(1)Patterns: Mottled browns and tans, all shades of brown, brown with white irregular circles

(2)Color Range: White, Tan, Brown

(3)Texture: Small irregular branching Papillea/Cirri

(3)Camouflage: Color and texture matching on live rock

E. Macropus ?
    (Species unclear)

1. Common Names

a)Luteus

1)Description is of larger animal but often identified this way by divers

2. Size
(personal observation)

a)Min Tank: 45+ gallons

b)Mantle: 5 cm (~2")

c)Arms: 23 cm (~9")

3. Attributes

a)Origination: Indonesia/Philippines

(1)Warm water species (75-80 deg F)

b)Most active: Late PM early AM (nocturnal)

c)Egg Size: Small

4. Identification

a)Arms

(1)Sucker Ring Color: none noted

(2)Webbing: Shallow depth about 1/5 the arm length. Ends where arms branch (about mantle length)

(3)Front 4 arms (L1,L2,R1,R2)considerably thicker and longer than back 4 (L3,L4,R3,R4). Back arms are rarely used for more than balance (personal observation).

b)Mantle and Head

(1)Arm:Mantle Ratio: 5:1

(2)Eyes: ~1/4 mantle size

(3)EyeStalk: Medium with definite narrowing between eye stalk and mantle

c)Crypsis

(1)Patterns: Red with white spots, white with iridesecent green, Brown (much like small O.briareus

(2)Color Range: Red, brown, white

(3)Texture: Papillea/Cirri minimal

F. Octopus mercatoris
    (Adam 1937)

1. Common Names

a)Caribbean/Atlantic/ Dwarf

b)Often mislabeled

(1)jobini

2. Size

a)Min Tank: 20 gallons

(1)Larger tank NOT recommended for a single animal

(2)May be kept in multiples if sI-Bblings, living together in the wild and possibly if similar in size when introduced

b)Mantle: 4 cm (~1.5")

c)Arms: 10 cm (~4")

3. Attributes

a)Origination: Caribbean/Southern Atlantic Coast

(1)Warm water species (72-80 deg F)

b)Most active: Late PM early AM (crepuscular - nocturnal)

(1)Consistent red lighting with no ambient works well to encourage viewing activity

c)Egg Size: Large

(1)Most successful of the octopuses raised and mated in aquariums (both hobby and lab environments)

4. Identification

a)Arms

(1)Sucker Ring Color: none noted

(2)Webbing: Shallow depth about 1/5 the arm length. Ends where arms branch (less than mantle length)

(3)Arms are delicate looking and thin, tapering quickly, suckers appear frill like and take most of the arm width.

b)Mantle and Head

(1)Arm:Mantle Ratio: 2.5:1

(2)Eyes: ~1/3 mantle size (proportionally large)

(3)EyeStalk: Minimal with eyes appearing attached to the head

(a)Large eyes give the appearance of a neck at the top of the webbing

c)Crypsis

(1)Patterns: Red with white patches, Brown

(2)Color Range: Red, brown, white

(3)Texture: Papillea/Cirri minimal

(3)Camouflage: Often seen in den with one or two arms over head between eyes

 

 

V. Lifespan

A. Home Aquarium Sized Animals live About 1 Year

1.Dwarfs slightly less 8-13 months

2.Cold water species slightly more 12-18 months

a)Dr. Roy Caldwell succeeded in keeping a bimac an unprecedented almost 3 years

B. Spotting Senescence

1. Both Male and Female Stop Eating and Visibly Shrink

a)Female dies shortly after eggs hatch

b)Males live about the same length of time but are more active in their last months

2. Cork Screw Arms

3.Muscle Loss, weak grip

4. Gray Coloration, Minimized Patterning and Color Changes

5.Enlarged Siphon and Heavy Breathing

6.Listlessness or Wandering without Purpose

C. Hints on Identifying a Younger Octopus

1.Translucent Skin

2.Thin, Uniform Arms

3.Mantle Girth and Control

a)Full adult will show an indention about mid-mantle

4.Patches That Do Not Color

a)This may occur in younger animals from damage but is more prevalent in adults

5.Rapid Growth

6.Shy and reclusive until 4-5 months at time growth rate slows