Improving Keeping for Octopuses by Testing Different Escape-Proof Designs on Tanks for “Big Blue Octopus” (Octopus cyanea)

Keishu Asada,Michael J Kuba,Tamar Gutnick,Fabienne Ziadi-Künzli,Zdeněk Lajbner,Ryuta Nakajima,Jonathan Miller,Takahiro Nishibayashi

doi:10.3390/app11188547

Keishu Asada, Michael J Kuba + Show 6 more

Open Access

https://doi.org/10.3390/app11188547

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Abstract

Octopus cyanea has a wide range of natural distribution and is interesting for scientific research. However, unlike Octopus vulgaris, the species is poorly studied, and few data exist on best practices for keeping them. One of the most common reasons for losing octopuses in human care is their ability to escape from holding tanks. Adult Octopus cyanea (n = 33) were locally collected in Okinawa throughout the year. All animals were housed at the laboratory facilities at the Marine Station of the Okinawa institute of Science and Technology. Animals were kept in a flow-through saltwater system in three different types of holding tanks ranging from 550 L to 600 L tanks or in 2000 L tanks, all with an environment enriched with clay pots or natural rocks as dens. They were fed a daily diet of dead fish or live or dead crustaceans ad libitum. To characterize the effectiveness of different keeping conditions, we compared escape attempts and non-natural deaths during the animals’ time under human care. We found that two types of tanks, the 600 L transparent acrylic glass tanks with weighted lids and the 2000 L tanks with synthetic grass lined walls, had significantly fewer escapes than the 550 L tanks.

Highlights

Cephalopods and especially octopuses have fascinated scientists and the public for decades
In the 1920s, researchers reported that octopuses kept in the Zoological Station of Naples moved from their aquarium to a nearby aquarium to hunt lobsters or other prey [5,6], underscoring the difficulty in containing these escape artists
The efforts to prevent escape led to a wide variety of different keeping strategies, many of which remain unreported

Summary

Introduction

Cephalopods and especially octopuses have fascinated scientists and the public for decades. L aquaculture opaque tanks adapted for use with octopuses, with either (c) a loss net fastened into 1a rail,. (d)standard a weighted clamped plexiglass tanks adapted useiswith octopuses, either (c) a net fastened into a rail, or (d) a weighted and3clamped plexiglass lid. In the present study we report on several different sizes and types of keeping con1.tainers, Tankas1A—we used custom transparent adaptations acrylic lids with holessuccess cut in in forkeeping water well as different typescut of anti-escape and their inflow hose and air bubbler hose. Compared to its temperate climateacrylic cousin, Octopus vulgaris, this species poorly studied, Tank Type used custom-cut lids with holes for water inflowisand an air buband The few data exist on best practices forthe keeping them [6,11,12]. Lids were secured on top of sunken inward-facing (Figure 2c)

Materials and

Maintenance

Escape

Discussion

Conclusions