<p>Supplementary Information</p><p>Role of Huge Geometric Circular Structures in the Reproduction of a</p><p>Marine Pufferfish</p><p>Hiroshi Kawase1*, Yoji Okata2 & Kimiaki Ito3</p><p>1Coastal Branch of Natural History Museum and Institute, Chiba, 123 Yoshio, Katsuura,</p><p>Chiba 299-5242, Japan, 2Higashi-Komagata, Sumida-ku, Tokyo 130-0005, Japan,</p><p>3Marine Station Amami, Yadorihama, Setouchi, Oshima, Kagoshima 894-1523, Japan.</p><p>*Correspondance to [email protected]</p><p>1 Supplementary Video Legends</p><p>Supplementary Video 1 | Male passing patterns of O-in, I-in, and C on the early stage of the circular structure construction. See text for the abbreviations of passing patterns. The categorization of zones is shown in Fig. 5. The video was shot by K. Ito at</p><p>Seisui on 21 April 2012.</p><p>Supplementary Video 2 | Male passing patterns of O-in, I-in and C on the middle stage of the circular structure construction. See text for the abbreviations of passing patterns. The video was shot by K. Ito at Katetsu on 29 May 2012.</p><p>Supplementary Video 3 | Male passing pattern of C on the middle stage of the circular structure construction. See text for the abbreviation of passing pattern. The video was shot by K. Ito at Katetsu on 29 May 2012.</p><p>Supplementary Video 4 | Male passing patterns of C and I-out on the middle stage of the circular structure construction. See text for the abbreviations of passing patterns. The video was shot by K. Ito at Katetsu on 10 July 2011.</p><p>Supplementary Video 5 | Male passing patterns of I-out and O-out on the middle stage of the circular structure construction. See text for the abbreviations of passing patterns. The video was shot by K. Ito at Katetsu on 29 May 2012.</p><p>2 Supplementary Video 6 | Male passing patterns of O-in, I-in, C and I-out on the final stage of the circular structure construction. Decoration behavior (Dec) is also recorded between C and I-out. See text for the abbreviations of passing patterns. The video was shot by K. Ito at Katetsu on 12 July 2011.</p><p>Supplementary Video 7 | Male (smaller individual) courtship behavior and female inspection of male’s nest site observed on the day of and on the day before spawning. The video was shot by K. Ito at Katetsu on 12 July 2011.</p><p>3</p>