. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 1. Levels of tentacle expansion in colonies of the stony coral Faviafavus. Five levels were arbitrarily designated as follows: 0 = full contraction. 1 = 25% expansion. 2 = 50% expansion, 3 = 75% expansion, 4 = 100% expansion. Each score refers to a whole coral colony. Low flow rate limits the diffusion of materials in the water column to and from coral tissues, thereby regulating and reducing metabolic rates (Patterson and Sebens, 1989; Patterson et ai, 1991). zooxanthellae productivity (Denni- son and Barnes, 1988; S
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 1. Levels of tentacle expansion in colonies of the stony coral Faviafavus. Five levels were arbitrarily designated as follows: 0 = full contraction. 1 = 25% expansion. 2 = 50% expansion, 3 = 75% expansion, 4 = 100% expansion. Each score refers to a whole coral colony. Low flow rate limits the diffusion of materials in the water column to and from coral tissues, thereby regulating and reducing metabolic rates (Patterson and Sebens, 1989; Patterson et ai, 1991). zooxanthellae productivity (Denni- son and Barnes, 1988; Shick, 1990; Patterson et ai, 1991), and nutrient uptake (Atkinson and Bilger, 1992). Oxygen builds up to high levels within and above coral tissue surfaces during the day as a result of photosynthesis, and is extremely depleted near those surfaces at night due to respiration; both gradients are reduced, improving delivery of dissolved substances to and from tissues, with even small increases of flow speed (Shashar and Stambler, 1992; Kuhl et ai, 1995; Shashar et ai, 1996). Polyp size, tentacle morphology, and tissue surface area vary widely among coral species, and all three factors contribute to prey encounter and capture rate. Porter (1976) suggested that large polyps with elongate tentacles special- ize in zooplankton capture, at the expense of high surface area conducive to photosynthesis. However, more recent evidence shows that certain small-polyped corals are able to capture almost the same size range of prey as do those with larger polyps, and actually have much higher rates of prey capture per unit biomass because of the high surface area of the tentacles that they expose to moving water (Sebens. 1987a). The small-polyped coral Madracis mirabilis cap- tures 30 times more zooplankton per coral biomass than does the much larger-polyped Montastrea cavernosa (Se- bens et ai, 1996). The biomass of polyps of M. mirabilis is only l/90th of the biomass of M. cavernosa polyps,
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
