Zoological Studies

Vol. 57, 2018

(update: 2018.05.24; 06.14) 

Direct Growth Measurements of Two Deep-sea Scalpellid Barnacles, Scalpellum stearnsii and Graviscalpellum pedunculatum

Yoichi Yusa1,*, Natsumi Yasuda1, Tomoko Yamamoto2, Hiromi Kayama Watanabe3, Takuo Higashiji4, Atsushi Kaneko4, Kazuki Nishida5, and Jens T. Høeg6

1Nara Women’s University, Kitauoya-nishi, Nara 630-8506, Japan
2Kagoshima University, Kohrimoto 1-21-24, Kagoshima 890-8580, Japan
3Japan Agency for Marine-Earth Science and Technology, Natsushima 2-15, Yokosuka 237-0061, Japan
4Okinawa Churaumi Aquarium, Motobu-cho, Okinawa 905-0206, Japan
5Kagoshima City Aquarium, Kagoshima 892-0814, Japan
6University of Copenhagen, Universitetsparken 4, Copenhagen DK-2100, Denmark

(Received 5 March 2018; Accepted 4 May 2018; Communicated by Benny K.K. Chan)

Yoichi Yusa, Natsumi Yasuda, Tomoko Yamamoto, Hiromi Kayama Watanabe, Takuo Higashiji, Atsushi Kaneko, Kazuki Nishida, and Jens T. Høeg (2018) Little is known about the growth rates of invertebrates living in ordinary deep-sea habitats such as continental slopes. Thus, the growth rates of two species of the deep-sea scalpellid barnacles, Scalpellum stearnsii and Graviscalpellum pedunculatum, were studied in two aquaria (at Nara and Okinawa Churaumi, Japan). In addition, growth of an S. stearnsii individual after 1 year of deployment was measured in the field. Overall, adult individuals of both species showed slow growths over 8 months (at Nara) and 2 years (at Okinawa) of rearing (e.g., at Nara: 2.0 ± 3.6 μm d-1 for S. stearnsii and 5.9 ± 2.7 μm d-1 for G. pedunculatum; mean ± SD). In contrast, growth rates of juvenile S. stearnsii at Nara were greater (15 ± 7.7 μm d-1). The in situ growth rate of the adult S. stearnsii (3.4 μm d-1) was greater than the average, but within the range of the rates of similar-sized individuals recorded in aquaria. Compared with other pedunculate barnacles, both species show small growth rates typical for deep-sea animals.

Key words: Cirripedia, Field measurement, Growth rate, Pedunculata, Rearing.

*Correspondence: E-mail: yusa@cc.nara-wu.ac.jp