title: Feeding behavior and digestive physiology in sea cucumber Apostichopus japonicus.
abstract: The feeding behavior and digestive physiology of the sea cucumber, Apostichopus japonicus are not well understood. A better understanding may provide useful information for the development of the aquaculture of this species. In this article the tentacle locomotion, feeding rhythms, ingestion rate (IR), feces production rate (FPR) and digestive enzyme activities were studied in three size groups (small, medium and large) of sea cucumber under a 12h light/12h dark cycle. Frame-by-frame video analysis revealed that all size groups had similar feeding strategies using a grasping motion to pick up sediment particles. The tentacle insertion rates of the large size group were significantly faster than those of the small and medium-sized groups (P<0.05). Feeding activities investigated by charge coupled device cameras with infrared systems indicated that all size groups of sea cucumber were nocturnal and their feeding peaks occurred at 02:00-04:00. The medium and large-sized groups also had a second feeding peak during the day. Both IR and FPR in all groups were significantly higher at night than those during the daytime (P<0.05). Additionally, the peak activities of digestive enzymes were 2-4h earlier than the peak of feeding. Taken together, these results demonstrated that the light/dark cycle was a powerful environment factor that influenced biological rhythms of A. japonicus, which had the ability to optimize the digestive processes for a forthcoming ingestion.
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, Shandong, China; Ocean University of China, 5 Yushan Road, Qingdao 266003, Shandong, China.
authors.forename: Jiamin
authors.initials: J
authors.lastname: Sun
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, Shandong, China. Electronic address: zhanglibin@qdio.ac.cn.
authors.forename: Libin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, Shandong, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, Shandong, China.
authors.forename: Chenggang
authors.initials: C
authors.lastname: Lin
authors.affiliation: Ocean University of China, 5 Yushan Road, Qingdao 266003, Shandong, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.affiliation: Shandong Blue Ocean Science and Technology Co., Ltd., Laizhou 261400, Shandong, China.
authors.forename: Rentao
authors.initials: R
authors.lastname: Kan
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, Shandong, China. Electronic address: hshyang@ms.qdio.ac.cn.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Yang
mesh_terms: D000681:Amylases / Q000378:metabolism; D000818:Animals; D049628:Body Size / Q000502:physiology; D004068:Digestive System Physiological Phenomena; D004435:Eating / Q000502:physiology; D005243:Feces; D005247:Feeding Behavior / Q000502:physiology*; D007259:Infrared Rays; D008049:Lipase / Q000378:metabolism; D009043:Motor Activity / Q000502:physiology; D010434:Pepsin A / Q000378:metabolism; D010507:Periodicity; D017440:Photoperiod; D047528:Stichopus / Q000502:physiology*; D014741:Video Recording
chemical_list: D008049:Lipase; D000681:Amylases; D010434:Pepsin A
keywords: Apostichopus japonicus; Digestive enzyme; Feeding rhythm; Sea cucumber; Size; Tentacle