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Evaluating Toys for Octopuses (Enteroctopus dofleini, Cephalopoda)

<< Cephalopod Articles | By Roland C. Anderson, The Seattle Aquarium and Andrea Leontiou, Byram Hills High School

Octopus Toys - Enrichment
Figure 1. The three toys presented individually to two octopuses. These were named Ball, Cow, and Pliers.

Introduction

Octopuses would seem to be good candidates for environmental enrichment. They are the most intelligent invertebrate, being able to learn to negotiate simple mazes, open jars, engage in play behavior and exhibit individual personalities (Mather and Anderson, 2000). Although aspects of octopus enrichment have been documented (Wood and Wood, 1999; Rehling, 2000; Anderson and Wood, 2000), it remains unknown how beneficial octopus enrichment is to the animals since there is yet no way of measuring it (Anderson and Wood, 2000). Rehling (2000) noticed increased activity in octopuses with enrichment but Anderson and Wood (2000) point out that increased activity could be a sign of disturbance or perseveration (Shepherson, 1998). Boal et al. (2000) have shown that enrichment benefits the learning and memory in cuttlefish (Sepia sp.).

Since octopuses have demonstrated play behavior (Mather and Anderson, 1999), allowing them access to "toys" has been one aspect of their enrichment (Anderson, 2003). Mark Rehling at the Cleveland Zoo has kept a notebook of enrichment items used on octopuses (including toys) as reported by public aquariums keeping octopuses. The toys appear to have several aspects in common. First, they allow exploration of the toy, which is a preliminary to play behavior (Mather and Anderson, 1999). Secondly they contain parts moveable by the octopus's arms and suckers (Anderson, 2003). Thirdly, some of the toys had parts with direct connections to other moveable parts via levers, gears, or linkages (Anderson, 2003). But it remains unknown what types of toys give the best exploration/play experience. The purpose of this study was to find what makes a good octopus toy based on octopus handling times. Finding a good octopus toy would allow better enrichment for captive animals and hence better health (Shepherdson, 1998).

Materials and Methods

Several types of child toys were purchased based on three criteria: exploration potential, maneuverability, and linkages to reactions (levers). The three toys chosen were a pair of blue colored pliers (Pliers), a ball of interlocked rings (Ball), and a cow-shaped object with three moveable rings suspended from the bottom (Cow) (see Photo 1), all made of plastic.

Each toy was presented to two giant Pacific octopuses (Enteroctopus dofleini (Wülker, 1912), a male and a female, the species most displayed in public aquariums (Carlson and Delbeek, 1998) held off-exhibit at the Seattle Aquarium in fiberglass tanks 1.3 X 1.3 m with water 1 m deep. Each toy was presented 9 times, once in the morning and twice in the afternoon at least two hours apart and the times of handling were observed. A different toy was presented at each experiment to each octopus. Obviously, there would be habituation in the course of the trials but the best and most interesting toy for the octopuses would have the highest handling time and lowest habituation.

Results

Trial numberBallPliersCow
1284384
218250
3167102
42122
521188
6278
76164
831271
91899
    
Mean271135
Table 1. Mean handling time in seconds of each toy by two octopuses (Enteroctopus dofleini) over nine presentations.

The mean handling times of the toys by the octopuses were clearly different (Table 1). Pliers was held the least at mean 11 seconds and Cow the most at mean 35 seconds. These handling times were significantly different (X2(2) = 299: p<0.001).

Octopus Enrichment
Figure 1. Handling by octopuses of the three toys (Ball, Pliers, Cow) and habituation as evidenced by a trendline (MS Excel) for the Cow toy.

Habituation was certainly present in the handling times, particularly in Ball and Pliers (see Figure 1) but much less so for Cow as evidenced by the slopes of the best-fit curves (MS Excel).

Discussion

It was not surprising to find that there was differences in handling times of the different toys. Anderson (2003) found differences in handling times of different toys in a casual setting. It would be expected that a fairly intelligent animal such as an octopus (Mather and Anderson, 2000) would hold a more complicated toy and explore it longer than a simple toy. Clearly, the more complicated the toy with the most moving and moveable parts, the longer the handling time and the greater the enrichment. On the basis of these findings, we recommend that octopuses be presented more complicated toys with multiple moving and moveable parts for their enrichment.

What was not expected was the brevity of handling times. The toys were frequently dropped after holding them for only two seconds, compared to the hours of holding times reported by Anderson (2000), particularly since one of the toys was the same (Pliers). It may be that these octopuses were just less inclined to explore/play; individual octopuses have different temperaments (Mather and Anderson, 1993; Sinn, et al., 2001). But even if the exploration/play times are brief, they still should be given to octopuses for added enrichment, enrichment that is clearly called for in keeping intelligent animals such as octopuses, in both public aquariums and laboratories.

References

Anderson, R.C. 2003. Octopus enrichment at the Seattle Aquarium. The Shape of Enrichment.12(2):7-8.
Anderson, R.C. & J.B. Wood. 2001. Enrichment for giant Pacific octopuses: happy as a clam? Journal of Applied Animal Welfare Science. 4(2):157-168.
Boal, J.G., B.U. Budelmann, & L. DICKEL. 2000.The effect of early experience on learning and memory in cuttlefish. Developmental Psychobiology. 36:101-110.
Carlson, B.A. & J.C. Delbeek. 1999. Cephalopod husbandry: progress and problems. 1999 AZA Ann. Conf. Proc.
Mather, J.A. & R.C. Anderson. 1999. Exploration, play, and habituation in Octopuses (Octopus dofleini). J. Comp. Psych. 113: 333-338.
Mather, J.A. & R.C. Anderson. 2000. Octopuses are smart suckers! Available online: http://www.thecephalopodpage.org/smarts.php.
Rehling, M.J. 2000. Octopus prey puzzles. The Shape of Enrichment. 9(3)
Shepherdson, J.D. Mellen & M. Hutchins (eds.). 1998. Second nature: environmental enrichment for captive animals. Smithsonian Institution Press (Washington). 350 pp.
Sinn, D.L., N.A. Perrin,, J.A. Mather, & R.C. Anderson. 2001. Early temperamental traits in an octopus (Octopus bimaculoides). Journal of Comparative Psychology, 115(4).
Wood, J.B & D.A. Wood. 1999. Enrichment for an advanced invertebrate. The Shape of Enrichment. 8(3)1-5.


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