Algivore or Phototroph? Plakobranchus ocellatus (Gastropoda) Continuously Acquires Kleptoplasts and Nutrition from Multiple Algal Species in Nature

• DOI: 10.1371/journal.pone.0042024
• Publication Date: 2012-07-25T21:26:12Z
• Authors: Taro Maeda; Euichi Hirose; Yoshito Chikaraishi; Masaru Kawato; Kiyotaka Takishita; Takao Yoshida; Heroen Verbruggen; Jiro Tanaka; Shigeru Shimamura; Yoshihiro Takaki; Masashi Tsuchiya; Kenji Iwai; Tadashi Maruyama
• Keywords: Slug

The sea slug Plakobranchus ocellatus (Sacoglossa, Gastropoda) retains photosynthetically active chloroplasts from ingested algae (functional kleptoplasts) in the epithelial cells of its digestive gland for up to 10 months. While feeding behavior has not been observed natural habitats, two hypotheses have proposed: 1) adult P. uses kleptoplasts obtain photosynthates and nutritionally behaves as a photoautotroph without replenishing kleptoplasts; or 2) it mixotroph (photoautotroph herbivorous consumer) replenishes continually periodically. To address question which hypothesis is more likely, we examined source temporal changes kleptoplast composition nutritional contribution. By characterizing diversity using rbcL sequences, found that harvests at least 8 different siphonous green algal species, than one species are present each individual slug, differs temporally. These results suggest wild often feed on multiple they fresh chloroplasts. estimating trophic position starved stable nitrogen isotopic amino acids, showed despite abundance kleptoplasts, their do contribute greatly nutrition ocellatus, but form significant slugs. nature consistent with insights molecular analyses indicating frequently replenished algae, leading conclusion populations rely photosynthesis mainly digestion algae.