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THE CORAL TRIANGLE: HEARST BIODIVERSITY EXPEDITION 
Figure 1. The coconut octopus, Amphioctopus marginatus (Taki, 1964), in its natural habitat in the Philippines. Note 
the “veined” appearance and the opalescence along the suction cups (defining characters used to identify appropriate spec¬ 
imens for collecting), as well as this individual’s use of multiple (empty) bivalve shells as a portable den. Photo by Bart 
Shepherd. 
tools as a portable defense meehanism (Finn et al. 2009). Amphioctopus marginatus have been 
observed earrying eoeonut shells under their bodies, ‘stilt-walking’ on the tips of their arms, and 
bringing two halves of a coconut shell together while hiding inside and rolling the shells across the 
sediment. Because it is presumed that the shell is being carried by the octopus for future (rather 
than immediate) use, and due to the complexity involved with correctly manipulating two differ¬ 
ent coconut shells into a single functioning “tool”, these unique behaviors may satisfy the defini¬ 
tion of tool use. However, it may be the case that the use of coconut shells by these octopuses is 
indeed for immediate use as protection from substrate dwelling predators. Amphioctopus margina¬ 
tus is also one of several species of octopuses known to exhibit bipedal locomotion (Huffard et al. 
2005). 
There have been very few in situ research studies on this species. Huffard and Godfrey-Smith 
(2010) documented the details of Amphioctopus marginatus mating behavior. The male and female 
were observed to be in close proximity during mating, with periods of crawling along the open sand 
by both sexes. During mating, the male was observed ‘reaching’ his hectocotylus, a modified ten¬ 
tacle used to pass spermatophores into the female mantle cavity, and holding it horizontally above 
the substratum. It is unknown whether the ‘reaching’ behavior is necessary for mating, or how 
many spermatophores were passed to the female during mating. 
