Octopus species are well known for their use of various camouflaging techniques to avoid predators in the depths of the ocean. Previous studies of octopus camouflage techniques have revealed that some species of octopus bury themselves into the sand on the ocean floor to be invisible to predators. Breathing, however, is a problem for these species. They need to either remain very close to the surface of the sand (close to the predators!) or stick part of their bodies out into the dangerous waters to breath. One particular octopus species, the Southern Sand octopus or octopus kaurna seems to have found a solution to this problem.
By using jets of water, this species is able to temporarily create a region on the sand surface that is very similar to quicksand. After this, the octopus is able to squirm its body around 20 centimeters under the surface of the sand. The problem of breathing is solved by a chimney type structure up to the water. In this home under the sand floor, the octopus is able to stay out of sight and out of danger. It emerges from this underground shelter at night to scavenge for food.
The construction of the sandy home requires skill and unique building materials. The first step the octopus takes is liquefying the sand. It does this by shooting jets of water at the surface of the sand, making the surrounding water murky. Then it uses its 8 long, flexible arms to dig into the loosened surface, while continuing to shoot water out. Once the octopus has gone down far enough, it pushes two long arms back to the surface. In addition, it coats the inside surface of its home with mucus which prevents the sand walls from collapsing. The chimney that it creates using its arms is cleared of any remaining debris with one large exhale. The overall construction is very comfortable for the octopus. It has enough space to fit its whole body into the main chamber without touching the mucus-lined sand walls.
Why is this method of camouflage so important? According to Jasper Montana of the University of Melbourne this species is “the first known cephalopod to burrow.” This species might have learned this method of hiding over time because it naturally lacks some of the other camouflage traits of other species. Another theory is that this species developed this method as it works well with its feeding habits. This species feeds primarily on worms and small crustaceans. Scientists have found these creatures within the octopuses’ chimney shaft. In other words, the food comes to the octopus while it rests in its home. Whatever the reason for this evolution may be, it is a very unique and innovative construction and serves its intended purpose very well.
Teja Ravivarapu is a freshman from Sid Richardson College at Rice University.
1. Montana, J.; Finn, J.K.; Norman, M.D. Liquid sand burrowing and mucus utilisation as novel adaptations to a structurally-simple environment in Octopus kaurna. Behavior 2015, 1-11.
2. Blaszczak-Boxe, A. Octopus Makes Own Quicksand to Build Burrow on Seabed. https://www.newscientist.com/article/dn28194-zoologger-octopus-makes-own-quicksand-to-build-burrow-on-seabed/ (accessed 10/6/15), part of Newscientist
3. Norman, M.D. Octopus Berrima. http://www.environment.gov.au/cgi-bin/species-bank/sbank-treatment.pl?id=77076 (accessed 10/6/15), part of Australian Department of the Environment Species Bank