CO-ORDINATION IN A SCYPHISTOMA

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Abstract
The scyphistoma of Amelia unrila was stimulated electrically and mechanically in various well defined regions. Each of these regions is neurologically independent in that the effects of the stimulation are localized to just one region of the polyp. Co-ordination of the different regions during prey capture and ingestion is still possible however because of the arrangement of the parts of the polyp in which one action sets off another one mechanically. The polypoid form of the scyphistoma is a geometrical arrangement allowing mechanical co-ordination. Such a co-ordination mechanism would not be suitable for the life of a medusa whose complicated problems necessitate neurological connections between the body regions for their co-ordination. On the principle that simple organisms arose first during evolution, it is maintained that the polypoid preceded the medusoid form in the Class Scyphozoa. Of the three polypoid types viz. hydropolyp, scyphopolyp and anthopolyp, the scyphopolyp has the simplest neuromuscular system and behavior.

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