. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure I. Inside-out oriented Aurelia aurita polyp. 5 nun (Ml) and 70 nun (right) alter capture of an Artemia nauplnis {previously stained lor 2-) h in /) 01'^ carmine in seawaler to improve contrast). At 70 mm. the anterior part of the Artemia (white arrow) wax wrapped hy a .septum and gastrodermal (olds and has been digested, whereas the tail (Mack arrow) had no contact with the gastrodermis and is still intact The har represents mm. f: gastrodermal fold, g: glass rod. s: septum, t ten- tacle the eye was 65 min (range
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure I. Inside-out oriented Aurelia aurita polyp. 5 nun (Ml) and 70 nun (right) alter capture of an Artemia nauplnis {previously stained lor 2-) h in /) 01'^ carmine in seawaler to improve contrast). At 70 mm. the anterior part of the Artemia (white arrow) wax wrapped hy a .septum and gastrodermal (olds and has been digested, whereas the tail (Mack arrow) had no contact with the gastrodermis and is still intact The har represents mm. f: gastrodermal fold, g: glass rod. s: septum, t ten- tacle the eye was 65 min (range 55-80 min). Digested prey frag- ments were endocytosed in the same gastrodermal region. In- digestible fragments (mainly parts of the exoskeleton) were transported orally and released to the medium. In summary, the processing of prey by inside-out oriented polyps was very similar as compared to rightside-out oriented polyps. Enzymes freely secreted by inside-out oriented polyps are di- luted by the medium by a factor of about 100,000 as compared to the gastric cavity of normally oriented polyps. The same is true for enzymes that leak from the contact region between the prey and the gastrodermis. The only effective extracellular di- gestive enzymes are those remaining at the region of contact ("contact digestion"). Our results demonstrating a fully func- tional digestion by inside-out polyps indicate that enzyme ac- tivities at the contact region are sufficient to explain extracellu- lar digestion in normally oriented A. aurita polyps. This in vivo evidence confirms the previous histological evidence obtained with fixed material. Wrapping by the septum and folds of the column wall en- hances the area of contact and helps to keep the enzymes close to the prey. Similar digestive mechanisms exist in Anthozoa (4, 5). where the prey is wrapped by mesenterial filaments; more- over, the mesenteries of Anthozoa also have dense ciliation. which is involved in particle transport
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
