. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. figure 2. Light micrographs of stages in the development of Fiingia scularia larvae. (A) Two-day-old planula larva, prior to development of a mouth. (B) Three-day-old feeding planula (m = mouth, mf = mucous strand with food particles attached, z = zooxanthella). (C) Polyp with tentacles, 6 days after settling. Zooxanthellae are visible as golden spheres. Planula length and polyp diameter, approximately 100 /xm. zooxanthellae, all ingested paniculate matter was digested or expelled by the following day. When larvae were about
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. figure 2. Light micrographs of stages in the development of Fiingia scularia larvae. (A) Two-day-old planula larva, prior to development of a mouth. (B) Three-day-old feeding planula (m = mouth, mf = mucous strand with food particles attached, z = zooxanthella). (C) Polyp with tentacles, 6 days after settling. Zooxanthellae are visible as golden spheres. Planula length and polyp diameter, approximately 100 /xm. zooxanthellae, all ingested paniculate matter was digested or expelled by the following day. When larvae were about 4 days old, they assumed a ball shape, ceased active swim- ming, and began creeping slowly over the substrate. Starting on day 5, the ball-shaped larvae began to settle. They spread out over the substrate and metamorphosed into volcano- shaped polyps, which began to develop tentacle buds sev- eral days after metamorphosis (Fig. 2C). Acquisition of zooxanthellae and onset of symbiosis Prior to the development of a functional mouth on day 3, planulae of F. sciituria did not become infected by experi- mentally added zooxanthellae. Once the mouth was func- tional, however, the planulae were able to acquire zooxan- thellae. When stimulated to feed, larvae indiscriminately ingested any particulate matter, including experimentally added zooxanthellae. Zooxanthellae either were ingested as part of a larger mass that was fully engulfed by the mouth, or they adhered to mucous strands that were ingested by the larvae. Figure 3A shows a zooxanthella adhered to a larval mucous strand, and Figure 3B shows several zooxanthellae surrounding and contained within the oral cavity of a larva. One hour after zooxanthellae were added, larvae were sam- pled and fixed for transmission electron microscopy. Figure 4 shows a representative planula 1 h postfeeding. in longi- tudinal section, with several algae resident in endodermal. Figure 3. Scanning electron micrographs detailing zooxanthella acqui- s
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
