Affiliation:
1. Biology Department, University of Victoria, Victoria, British Columbia,V8W 3N5, Canada
2. Department of Physiology, University Walk, Bristol BS8 1TD, UK
Abstract
SUMMARYThe hydromedusan jellyfish Aglantha digitale feeds on small planktonic organisms carried to the margin by tentacle flexions. During feeding, the manubrium bends across (`points') and seizes the prey with flared lips. In immobilized preparations, pointing to a source of electrical stimulation was accurate, 70% of the time, to within 15°. Cutting experiments showed that the conduction pathways concerned with pointing and lip flaring are located in eight radial strands consisting of a radial canal,a giant nerve axon and a bundle of small axons with FMRFamide-like immunoreactivity.Application of food juices to sites on the margin and tentacles evoked trains of impulses in the axon bundles (F events; conduction velocity 15.5±3.7 cm s-1) and in the epithelium lining the radial canals (E events; conduction velocity 28.5±3.5 cm s-1). Impulses were conducted circularly in the outer nerve ring (F events) or in the ring canal (E events).Unilateral flexions of the manubrium during pointing arise from preferential excitation of one or more of eight longitudinal `muscle bands' in the wall of the manubrium and peduncle. Lip flaring represents symmetrical contraction of all eight bands. Cutting experiments revealed that F events mediate pointing; E events mediate lip flaring. Thus the endodermal radial canals, which in other hydromedusae mediate protective `crumpling', provide the conduction pathway for manubrial lip flaring. Aglantha's alternative protective response – escape swimming – makes crumpling unnecessary, releasing the pathway for use in feeding.Trains of E events, generated in the manubrium during ingestion, propagate to the margin and inhibit rhythmic (slow) swimming with a duration that depended on their number and frequency. Inhibition of swimming appeared to facilitate transfer of food from the margin to the mouth, but how it comes about is unclear.
Publisher
The Company of Biologists
Subject
Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics
Reference43 articles.
1. Anderson, P. A. V. (1980). Epithelial conduction: its properties and functions. Progr. Neurobiol.15,161-203.
2. Arai, M. N. (1991). Attraction of Aurelia and Aequorea to prey. Hydrobiologia216/217,363-366.
3. Arai, M. N., McFarlane, G. A., Saunders, M. W. and Mapstone, G. M. (1993). Spring abundance of medusae, ctenophores and siphonophores off southwest Vancouver Island: possible competition or predation on sablefish larvae. Can. Tech. Rep. Fish. Aquat. Sci.1939,1-37.
4. Arkett, S. A. (1984). Diel vertical migration and feeding behavior of a demersal hydromedusan (Polyorchis penicillatus). Can. J. Fish. Aquat. Sci.41,1837-1843.
5. Arkett, S. A., Mackie, G. O. and Meech, R. W.(1988). Hair cell mechanoreception in the jellyfish Aglantha digitale. J. Exp. Biol.135,329-342.
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