Animal Diversity Web

Geographic Range

Indo-Pacific. Found most commonly in the tidal rock pools along the southern coast of Australia.

(Moynihan 1985. Sea World Inc 1996. Rogerson 1998)

• Biogeographic Regions
• australian
  • native
• indian ocean
  • native
• pacific ocean
  • native

Habitat

Most commonly found in rocky, shallow pools of water or in shallow corals. Also found under rocks in sandy or muddy stretches of bottom where alga is plentiful. Particularly common after storms when it can be found looking for crabs and bivalves.

(Moynihan 1985, Campbell 1998, Australian wildlife lectures 1998, Rogerson 1998, Park 1987)

• Aquatic Biomes
• coastal

Physical Description

The blue-ringed octopus is a small octopus that ranges in size from 4 mm at birth to up to 20 cm in adulthood. It is dark brown to dark yellow/ tan-yellow in coloring. The most outstanding characteristic of this species is the iridescent blue rings in the eye spots. These rings are reported to "glow" when an individual is aggravated.

(Campbell 1998. Rogerson 1998. Hanlon and Messenger 1996)

• Other Physical Features
• ectothermic
• bilateral symmetry

• Average mass

  26 g

  0.92 oz

Reproduction

The female will initiate reproduction by specific coloring and posturing. The male will then approach her to begin courtship. Courtship consists of "love play" (Wood, 1999) and caressing. The male will then use the hectocotylus, a modified arm consisting of a groove between the suckers and ending in a spoonlike tip, to deposit the sperm in the female's oviduct, which is located under the mantle. Shortly thereafter, the female will begin to lay her eggs and the brooding period will begin. Characteristic brooding of this species is for the female to carry the eggs in its arms. She will guard them for a period of fifty days, at which point they will hatch into planktonic "paralarva". Initially at birth, the octopus will be only 4 mm long. This stage of the life cycle, the young will float to the top and join the plankton for about a month. At the end of this time period they will once again return to the bottom to resume their normal life.

(Microsoft 1993. Boyle 1987. Wood 1999. Hanlon and Messenger 1996)

Behavior

The blue ringed octopus is a nonaggressive octopus and in general exhibits the typical behaviors of octopuses: anachoresis, burrowing, and aposematism. Anachoresis is living

in crevices and holes. Burrowing is where an octopus establishes a den or refuge for itself by excavation of sand, mud, gravel, and coral rubble. This can often pose a problem in an aquarium environment, where underground filters are common. Aposematism, or advertising toxicity, in this species includes the "glowing" (Campbell 2000) of the iridescent blue rings, and often a yellow and black striping of the body. In general, not much is known of use of these displays in this particular species.

(Hanlon and Messenger 1996, Campbell 1998, Wood 1999)

Food Habits

At one week of age, the blue ringed octopus will begin to eat crab pieces. As the octopus matures, it will begin to eat live crabs and bivalve mollusks. The octopus will either entice its prey into its vicinity and inject a poison into the water that will paralyze it or will inject the poison into its prey directly. It is also believed that the octopus will capture prey, forming an airtight pouch around it, and inserting the poison into the pouch, cause the prey to take the poison in through its respiratory system. The poison is a neurotoxin which causes paralysis, which is particularly fatal if the poison affects either the heart or repiratory system. To date there is no antitoxin. Generally though, humans are not considered prey to this creature and a bite from one seems to be more of a defensive response than anything else.

References: Boyle 1987. Microsoft 1993. Loadsman and Thompson 2000. Park 1987. Berry 1998.

Economic Importance for Humans: Positive

This species lacks an ink sac and therefore has become a common addition to the marine aquarium. This is much to the dismay of many toxicologists who feel that people selling and buying them are uninformed of the true danger they pose. This species also is used for its venom. One of Australia's major industries is its venom industry, in which the blue-ringed octopus plays a valuable role.

In addition this species has come under study to provide information on the mantle and the microscopic protrusions on the mantle of cephalopods.

(Hanlon and Messenger 1996. Parks 1987. Wood 1999)

Economic Importance for Humans: Negative

This species is considered one of the most dangerous animals in the sea because of the toxicity of its venom. In addition, the bite of the blue-ringed octopus is not painful. Therefore, there have been reported cases where people handled one and did not realize they had been bitten until the symptons of envenomation began to occur.

(Australian Wildlife Lectures 1998, Seaworld 1996, Park 1987)

Conservation Status

There was no information on conservation efforts made for the blue-ringed octopus. A problem has begun to arise surrounding the publicity of the toxicity of its venom. People have begun to over-react and kill octopuses encountered in shallow tidal pools.

(Park 1987)

• IUCN Red List

  Not Evaluated

Other Comments

Though the blue ringed octopus carries a toxin which can kill humans, there has never yet been a report of an octopus attacking a human. In general this species is nonaggressive and will only bite if picked up or stepped on.

The name Blue-ringed Octopus is actually given to a large group consisting of about five different species. Two of these are Hapalochlaena lunulata and Hapalochlaena fasciata. H. lunulata has larger rings than H. maculosa and is most commonly found on Australia's northern coast. H. fasciata has lines instead of rings on its body and is found only in New South Wales.

(Loadsman and Thompson 2000, Park 1987)

Contributors

Ashleigh MacConnell (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

References

Anonymous, 1993. Octopus. Microsoft Encarta 98 Encyclopedia, computer version '98.

Australian Wildlife Lectures, 1998. "Sealife" (On-line). Accessed 2/27/00 at http://www.scottware.com.au/awl/bite/sealife.htm.

Berry, S. 1998, 2-16-2000. "Seemingly Innocent" (On-line). Accessed 2/27/00 at http://www.aquarium.org/upwelling/upwelling13.htm.

Boyle, P. 1987. Cephalopod Life Cycles v.ll : Comparative Reviews. New York: Harcourt Brace Jovanovich Press.

Campbell, MD, E. 1998, 2/24/2000. "Blue-Ringed Octopus" (On-line). Accessed 2/26/00 at http://www.gulftel.com/~scubadoc/blueoct.htm.

Hanlon, R., J. Messenger. 1996. Cephalopod Behaviour. Cambridge: Cambridge University Press.

Loadsman, J., C. Thompson. 1-7-2000. "Marine Envenomations" (On-line). Accessed 2/27/00 at http://www.usyd.edu.au/su/anaes/marine_enven.html.

Moynihan, M. 1985. Communication and Noncommunication by Cephalopods. Bloomington: Indiana University Press.

Park, E. May, 1987. Around the Mall and beyond. Smithsonian, v.18: pp.28-32.

Rogerson, S. 07-18-1998. Travel: Just when you thought it safe...Consumer Report. The Daily Telegraph: pp.07+.

Sea World Inc., 1996. "Ask Shamu: Dangerous Sea Animals" (On-line). Accessed 2/26/00 at http://www.seaworld.org/ask_shamu/dangerous.html.

Wood, J. 2-1-00. "FAQs" (On-line). Accessed 2/26/00 at http://is.dal.ca/~ceph/TCP/faq.html.

Wood, J. 2-20-99. "Hapalochlaena lunulata" (On-line). Accessed 2/26/00 at http://is.dal.ca/~ceph/TCP/lunulata.html.