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Notes on the Behavior of the Hydroid, Corymorpha palma

Robert Wyman
American Zoologist
Vol. 5, No. 3, Behavioral Physiology of Coelenterates (Aug., 1965), pp. 491-497
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/3881173
Page Count: 7
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Notes on the Behavior of the Hydroid, Corymorpha palma
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Abstract

Corymorpha, like Porpita, exhibits a synchronous oral flexion, or "concert," of its proximal tentacles. As this is unlike the contractile writhings of siphonophoran zooids, the concert may be a significant character in linking the behavior of Porpita more closely to hydroids than to siphonophores. Except for this response the behavior of Corymorpha and Porpita are different. In Porpita a through-conducting system forms the only link between tentacles, whereas in Corymorpha both local and through-conducting systems connect tentacles. Corymorpha engages in rhythmic bottom-feeding using distal tentacles which have no homologue in Porpita. The mechanical properties of the musculo-skeletal system are different in the two, giving tentacle motions in Corymorpha a continuous appearance, and in Porpita a spasmodic appearance. Reduced glutathione, glycine, DL-serine, L-cysteine and L-glutamic acid can elicit a feeding response in Corymorpha. Sodium thioglycollate and sucrose elicit no response. Glycine is the most effective stimulant, ca. 5× 10-7 M solution being effective. L-glutamic acid gives the weakest response. The presence of chemicals alone can be sufficient to elicit the feeding reaction in starved animals. In moderately well-fed animals, touch may be required. In fully fed animals both touch and chemicals may be insufficient. Parker reports that when Corymorpha is shocked electrically on its stalk it will bend the stalk so as to apply the hydranth accurately to the stimulated spot. The response I found was a curling of the stalk toward the side stimulated, but not to a specific spot on the stalk. Chemical or tactile stimuli may be necessary for final location of the stimulated site. Parker reported that the response remained accurate even after several cuts had been made in the stalk. I could find no evidence for this.

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