11 July 2016

Meet Hank, the east Pacific red octopus

Left photo is is ©Finding Dory's red octopus Hank (Source: movie.disney.co.uk)  and on the right is its real-life counterpart, Octopus rubescens (Photo by Ken Phenicie Jr.).

The octopus is considered as one of the most elusive and intelligent of sea creatures [1]. We sure were fascinated with Hank, the animated counterpart of Octopus rubescens, more commonly known as the east Pacific red octopus. This species is known to inhabit the waters of Bering Strait, Alaska down to Baja California, from low intertidal to a depth of 210 m.  It can reach a total length of 45 cm [2] and lives up to two years [9]. It has a neutral color of red or reddish brown [3]. In the movie Hank wishes to live in captivity permanently, away from all the dangers of the wild. In reality though, juveniles are found among kelps [9] while adults settle on rock and soft bottoms [2]. It is a voracious predator of crabs [4] and also feeds on bony fish [4], mollusks, and euphausiids [6]. It can even drill holes on shells of the bivalve Venerupis philippinarum [5].

What makes them so interesting is beyond what we have encountered in the movie. Sure, they can change into a kaleidoscope of colors before and after capturing a prey. Based on one study, it displayed various colors before detection of a crab, turned light orange to gray during a free-swimming attack, colorless and almost transparent on landing, spotted or mottled upon grabbing the crab, and back to various colors. This series of color change may be associated with locomotor acts and postural adjustments [7]. Below is a video of O. rubescens feeding on a crab [8].

Because of its soft flexible body and small papilla (projections on its skin), O. rubescens can morph into different shapes and textures, an ability that is very useful against predation. At the point of detection, it can rapidly change color, shape or even texture, confusing and alarming its predator altogether [9].

Much like Hank’s crafty moves in Finding Dory, O. rubescens is truly capable of escaping captivity and surviving on land. According to Monterey Bay Aquarium, a juvenile O. rubescens sneaked into an aquarium using a sponge as a cover, and was only caught red handed (after a year in an exhibit) while walking in the middle of the night. Workers also noticed that the crabs in the exhibit were decimated [10].

And yes, this species has three hearts as other octopuses do: one pumps blood through the body, specifically for the organs, while the other two exclusively pump blood through the gills [1]. No doubt Hank, in the end, had the heart (or hearts?) to return and help Dory and her friends go back to their true home, the ocean.

To know more about O. rubsecens and other characters from Finding Dory, visit SeaLifeBase.

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[1] Nuwer, R. (2013, October 31). Ten curious facts about octopuses. Retrieved from http://www.smithsonianmag.com/science-nature/ten-curious-facts-about-octopuses-7625828/?no-ist
[2] Gotshall, D. W. (2005). Guide to marine invertebrates: Alaska to Baja California (2nd ed. revised). Sea Challengers.
[3] Biodiversity of the Central Coast (2014). Pacific red octopus – Octopus rubescens. Retrieved from http://www.centralcoastbiodiversity.org/pacific-red-octopus-bull-octopus-rubescens.html
[4] Boletzky, S. V., & Hanlon, R. T. (1983). A review of the laboratory maintenance, rearing and culture of cephalopod molluscs. Memoirs of the National Museum Victoria, 44, 147-187. Retrieved from https://www.researchgate.net/profile/Roger_Hanlon/publication/279192347_A_review_of_laboratory_maintenance_rearing_and_culture_of_cephalopod_molluscs/links/56b13e1008ae5ec4ed48808c.pdf
[5] Anderson, R. C., Sinn, D. L., & Mather, J. A. (2008). Drilling localization on bivalve prey by Octopus rubescens Bery, 1953 (Cephalopoda: Octopodidae). The Veliger, 50(4), 326-328. Retrieved from http://eprints.utas.edu.au/8464/
[6] Laidig, T. E., Adams, P. B., Baxter, C. H., & Butler, J. L. (1995).  Feeding on euphausiids by Octopus rubescens. California Fish and Game, 81, 77-79. Retrieved from
[7] Warren, L. R., Scheier, M. F., & Riley, D. A. (1974). Colour changes of Octopus rubescens during attacks on unconditioned and conditioned stimuli. Animal Behaviour, 22(1), 211-219. Retrieved from http://www.sciencedirect.com/science/article/pii/S0003347274800710
[8] NgomaMom (2014, May 21). East Pacific red octopus in the mood for food [Video file]. Retrieved from https://www.youtube.com/watch?v=_Wkl3exDmys
[9] Orwick, S. (2005). Crypsis, substrate preference and prey detection in the red octopus, Octopus rubescens (Berry, 1952). Retrieved from Oregon Institute of Marine Biology https://scholarsbank.uoregon.edu/xmlui/bitstream/handle/1794/8072/Orwick%2005.pdf?sequence=1&isAllowed=y
[10] Monterey Bay Aquarium (2016). Red octopus.  Retrieved from  https://www.montereybayaquarium.org/animal-guide/octopuses-and-kin/red-octopus