Prey selection in three species of the carnivorous aquatic plant Utricularia (bladderwort)
Archiv für Hydrobiologie Volume 146 Number 4 (1999), p. 449 - 470
published: Nov 24, 1999
ArtNo. ESP141014604005, Price: 29.00 €
Carnivorous plants supplement normal photosynthetic nutrition with sit-and-wait predation, killing and ingesting prey. I investigated and compared the diets of three sympatric species of the aquatic plant Utricularia (bladderwort). All three species caught planktonic prey taxa in lower proportions than available, whereas they captured prey living on or among plants and in or on the sediment in proportion to availability. A planktonic lifestyle, therefore, reduced a prey's risk of being captured by bladderworts. The diet of U. minor differed from that of U. intermedia/stygia, whereas the diet of U. vulgaris overlapped the other two species. Differences were explained by the relation between prey size and bladderwort trap size. U. minor, with small traps, caught mainly prey under 1 mm, U. intermedia/stygia, with mainly medium sized traps, caught mainly prey sized 1-4 mm and U. vulgaris, with equal proportions of both trap sizes, caught prey of both size classes. U. vulgaris also grew in deeper water than the other species. Thus, U. minor and U. intermedia/stygia both grew in shallow water, but captured different prey sizes, whereas U. vulgaris, that overlapped the other bladderworts in their diet, grew in deeper water than these.