Where do blue-ringed octopus live?

Some of the most fascinating places in the world are the depths of the seas and the oceans. These are home to many unique creatures that have the capacity to capture our eye. At the same time, they also pique our scientific curiosity. One such beautiful creature is the blue-ringed octopus.

Pretty colors, deadly nature

True to their name, blue-ringed octopuses have vibrant blue circles on their bodies. But these blue rings aren’t just pleasing to the eye. They also serve as part of the defense mechanism. The rings glow blue only when the octopus feels threatened. The blue color is due to the presence of special cells called iridophores . The vivid color acts as a warning signal to potential predators.

Aposematism is the use of bright colors to warn predators of an animal’s poisonous nature. If the octopus feels that the predator has not gone away and is still a threat, it releases a chemical. The chemical is called tetrodotoxin . The poisonous nature of this octopus is due to this toxin. This toxin can paralyze predator animals, and can eventually lead to death.

Where do they live?

Countries like Japan, the Philippines, and Australia. They occupy depths ranging from 0 to 50 meters. As they are nocturnal animals, they hide in nooks and corners during the day. Researchers believe that around 8 to 10 species of the blue ringed octopus exist. However, they have been able to characterize and name only 3 to 4 of them. The habitat of the octopus depends on the species it belongs to.

1. Greater blue-ringed octopus:

This species of octopus inhabits the Pacific Ocean. Countries like Sri Lanka, the Philippines, Australia, and Papua New Guinea harbor this animal. This species prefers shallow waters. Rocky areas with lots of sand are preferentially occupied by this species.

2. Southern blue-ringed octopus:

The southern coast of Australia harbors this species of octopus. They can be found up to a depth of 30 meters. Unlike the greater blue-ringed octopus, this species has a much-restricted geographical distribution.

3. Blue-lined octopus:

This species inhabits rocky areas and shallow coastal waters of Australia. They can be found up to a depth of 15 meters. They are very small in size. Hence, they can be found living in empty sea shells or discarded plastic bottles.

4. Hapalochlaena nierstraszi:

Researchers have reported only two occurrences of this species: once in 1938 in Andaman and once in 2012 in Chennai, near the Bay of Bengal. Apart from this, very little is known about this species.

The threat to habitat

Blue-ringed octopuses tend to occupy coral reefs and seagrasses. Pollution and human activities have adversely affected both of these habitats. This has put the home of these captivating creatures at risk. For instance, the increasing temperature of seawater has caused coral bleaching. An increase in the level of carbon dioxide has caused acidification of the water. This is another cause of worry.

Lastly, it is important to mention that these animals are extremely poisonous. Their beautiful color is a source of attraction for most of us. But we may not realize that we are in the vicinity of one of the world’s deadliest o creatures. So, if you happen to come across an octopus with bright blue rings, it would be wise to admire this beauty from a safe distance.

Glossary

Iridophores: Specialized cells responsible for color.

Aposematism: Phenomenon of using bright colors as a defense strategy to ward off predators.

Tetrodotoxin: A harmful chemical compound that can paralyze predator animals.

Nocturnal: Phenomenon of being active at night.

Acidification: Process of making the oceans more acidic due to reduction in pH.

Scientific Names

Greater blue-ringed octopus: Hapalochlaena lunulata

Southern blue-ringed octopus: Hapalochlaena maculosa

Blue-lined octopus: Hapalochlaena fasciata

Citations:

References

For Paragraph 1: Pretty colors, deadly nature

Hwang, D. S., Arakawa, O., Saito, T., Noguchi, T., Simidu, U., Tsukamoto, K., Shida, Y., & Hashimoto, K. (1989). Tetrodotoxin-producing bacteria from the blue-ringed octopus Octopus maculosus. Marine Biology, 100(3), 327–332. https://doi.org/10.1007/bf00391147
Mäthger, L. M., Bell, G. W., Kuzirian, A. M., Allen, J., & Hanlon, R. T. (2012). How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings? The Journal of Experimental Biology, 215(21), 3752–3757. https://doi.org/10.1242/jeb.076869

For paragraph 2: Where do they live?

Asakawa, M., Matsumoto, T., Umezaki, K., Kaneko, K., Yu, X., Gomez-Delan, G., Tomano, S., Noguchi, T., & Ohtsuka, S. (2019). Toxicity and Toxin Composition of the Greater Blue-Ringed Octopus Hapalochlaena lunulata from Ishigaki Island, Okinawa Prefecture, Japan. Toxins, 11(5), 245. https://doi.org/10.3390/toxins11050245
Hapalochlaena lunulata. (n.d.). Animal Diversity Web. https://animaldiversity.org/accounts/Hapalochlaena_lunulata/#:~:text=Habitat,of%20its%20soft%2Dbodied%20vulnerability.
Hapalochlaena lunulata – Greater Blue-ringed Octopus – Taxo4254 – Wiki.nus. (n.d.). https://wiki.nus.edu.sg/display/TAX/Hapalochlaena+lunulata+-+Greater+Blue-ringed+Octopus
Hapalochlaena maculosa. (n.d.). Animal Diversity Web. https://animaldiversity.org/accounts/Hapalochlaena_maculosa/#:~:text=Habitat,bottom%20where%20alga%20is%20plentiful.
Southern Blue-lined Octopus. (n.d.). The Australian Museum. https://australian.museum/learn/animals/molluscs/southern-blue-lined-octopus-hapalochaena-fasciata/
Sethi, S. N., & Rudramurthy, N. (2013). Blue ring Octopus, Hapalochlaena nierstraszi, from the Bay of Bengal along the Chennai Coast. CMFRI Repository. http://eprints.cmfri.org.in/9270/

Paragraph 3: The threat to habitat

White, A., Vogt, H., & Arin, T. (2000). Philippine Coral Reefs Under Threat: The Economic Losses Caused by Reef Destruction. Marine Pollution Bulletin, 40(7), 598–605. https://doi.org/10.1016/s0025-326x(00)00022-9
Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., Harvell, C. D., Sale, P. F., Edwards, A. M., Caldeira, K., Knowlton, N., Eakin, C. M., Iglesias-Prieto, R., Muthiga, N. A., Bradbury, R., Dubi, A., & Hatziolos, M. E. (2007). Coral Reefs Under Rapid Climate Change and Ocean Acidification. Science, 318(5857), 1737–1742. https://doi.org/10.1126/science.1152509