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A simple visual system without neurons in jellyfish larvae.

Karin Nordström·Rita Wallén·Jamie Seymour·Dan Nilsson
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Abstract

Earlier detailed studies of cnidarian planula larvae have revealed a simple nervous system but no eyes or identifiable light sensing structures. Here, we describe the planula of a box jellyfish, Tripedalia cystophora, and report that these larvae have an extremely simple organization with no nervous system at all. Their only advanced feature is the presence of 10-15 pigment-cup ocelli, evenly spaced across the posterior half of the larval ectoderm. The ocelli are single cell structures containing a cup of screening pigment filled with presumably photosensory microvilli. These rhabdomeric photoreceptors have no neural connections to any other cells, but each has a well-developed motor-cilium, appearing to be the only means by which light can control the behaviour of the larva. The ocelli are thus self-contained sensory-motor entities, making a nervous system superfluous.

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AnimalsLarvaMicroscopy, ElectronPhotoreceptor Cells, InvertebratePigments, BiologicalScyphozoaVision, OcularComparative StudyJournal ArticleResearch Support, Non-U.S. Gov't

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Karin Nordström, Rita Wallén, Jamie Seymour, Dan Nilsson. 2003-11-22. A simple visual system without neurons in jellyfish larvae.. https://doi.org/10.1098/rspb.2003.2504

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