Talk:Hydra viridis
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Can someone please provide references to support the statements here. I have no evidence that H. viridi has less symbiotic green algae in their gastrovascular cavity. (sic) than H. viridissima. Firstly the algae do not reside the the cavity but are inclusions within the cells of the endoderm (or gastrodermis as the Hydra (genus) article characterises it) More significantly, the differences between theses species is morphological and in distribution. I am also unaware that any one species of Hydra is more or less predatory than another, whether or not they have algal inclusions. Observations suggest otherwise and it may be that algal inclusions permits green algae to colonise different ecological niches. What is certainly true in observation is that the fully extended tentacles of H. oligactis are more than twice the length of H. viridis . But of this too, I cannot provide a source. I would strongly recommend only publishing sourced and verifiable information. Velela 09:10, 6 April 2006 (UTC)
- The article I referenced mentions this briefly. "To investigate interactions between the basal metazoan Hydra viridis and its symbiotic Chlorella algae, we generated aposymbiotic hydra lacking algae and compared them to symbiotic ones with regard to growth and sexual differentiation. Under standard feeding conditions, aposymbiotic polyps were generally less predacious than symbiotic polyps."
--Brazucs 16:19, 7 April 2006 (UTC)
Unfortunately, all the embedded links seem to reference the Wikepedia article rather than the source material. However, my recollection of similar research in the past is that there is evidence that if H. viridis is grown in the absence of its symbiotic Chlorella then it appears to be more active in seeking prey and tends to capture more prey organisms. However, this is not the same as saying the Hydra species which do not have symbionts are themselves more predatory. I have seen no evidence of this in years of studying Hydra. What is true is that, for example, H. oligactis tends to capture more prey per hour than H viridis but this difference can most easily be explained by the much greater length of tentacles possessed by H oligactis. Incidentally, as Wikpedia is widely read by non zoologist and zoologists alike, I would prefer the common English word Predacious rather than the Zoological specific work Predatory. Predatory in common parlance tends to imply an active hunting action as if ’’ Hydra’’ were pursuing ‘’Daphnia’’ in great bounding leaps across the veldt. Unfortunately, they are just a tad more sedentary than that! Velela 10:13, 10 April 2006 (UTC)
