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Animalia >Mollusca >Cephalopoda >Octopoda >Octopodidae >Octopus >

0. Helper: Yukihiko MATSUYAMA, Shoji NAKANO, Kazumasa HASHIMOTO, Tatsuya YURIMOTO, Sou NAGASOE, Seiei KANEMATSU, Atsushi ITO (Fisheries Research Agency)

1. Octopus vulgaris
a) Sampling area: Shimabara, the Ariake Sea, Japan
b) Sampling date: 26 April 2020
c) Body size: 1,740 g in wet weight
d) Acclimation: the octpus had been confined in a mesh bag in an aquarium with sea water flowing (19.1˚C) until 3 May 2020. Fed with the bivalves Crassostrea gigas and Mimachlamys nobilis.

2. Atrina sp.
a) Source: a specimen sampled from the artificial seeds that had been produced from the spawning of Atrina sp. on 25 June and 10 July 2018
b) Body size: 122.1 mm in shell length, 46.2 mm in shell height
c) Method for rearing: kept in the sea in a basket with anthracite

3. Apparatus for observation
a) Round aquarium: 500 L in volume, 105 cm in diameter, 77 cm in height
b) Octopus pot: 20 cm in diameter, 20 cm in height
c) Sediment: anthracite (2 mm in grain size)
d) Volume of sediment and seawater: the aquarium was filled with anthracite from the bottom to the 20 cm height and further with seawater to 50 cm height.

4. Experimental condition
a) Light: 24 ¦Ģ mol/m2/s
b) Water temperature”§ 22.7 ˚C
c) Salinity: 33
d) Aeration: none
e) Flow of seawater: none
f) CF: there were no aeration or flow of seawater, because such equipments generating bubble and water flow were possibly broken by the octopus

5. Time lapse camera
a) ModelӤ Brinno TLC 200 Pro
b) SettingӤ focus = 20 cm, frame rate = 20 fps, white balance = 2,800 inc., scene = twilight, HDR = high, interval = 2 seconds

6. Schedule
a) 26 April 2020: catch of the octopus at Shimabara
b) 28 April: transport of the octopus from Shimabara to Seikai National Fisheries Research Institute
c) 28 April to 3 May: acclimation of the octopus
d) 10:05, 3 May: the octopus was moved into the 500-L aquarium
e) 10:05, 3 May: the pen shell was transplanted on the anthracite in the 500-L aquarium
f) 11:27, 7 May to 14:45, 8 May: photographing (only the photographs recording the predation of the pen shell were uploaded)

7. Acknowledgements
Predatory animals were caught by Saga Ariake Fishery Cooperative Oura Branch and Shimabara Fishery Cooperative. Seed production of the pen shell indispensable for the present study was assisted by Nagasaki Prefectural Institute of Fisheries, Saga Prefectural Ariake Fisheries Research and Development Center, Fukuoka Fisheries and Marine Technology Research Center Ariakekai Laboratory, and Kumamoto prefectural Fisheries Research Center. The present study was financially supported by contract work with Ministry of the Environment, Japan. I am grateful to all of them.

(Data No.momo200728ov01b)

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