. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. POICILOGONY IN STREBLOSPIO BENEDICTI 501 LECITHOTROPHIC POPULATIONS ~~| Mission Bay, CA I Big Slough. TX 1 Tar Landing. NC 10 28/83. PLANKTOTROPHIC POPULATIONS •H Marine Environmental Research Lab, Narragansett Bay, Rl II I I II New Bedford Harbor. MA Tar Landing, NC 2 s/83 Sebastian R. FL Copano Bay. TX 80 NUMBER OF LARVAE PER BROOD 160 180 200 250 30O 350 FIGURE 3. Observed distribution of brood sizes are shown in three lecithotrophic and five planktotrophic Streblospio benedicti populations. adult setae (capillary setae a
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. POICILOGONY IN STREBLOSPIO BENEDICTI 501 LECITHOTROPHIC POPULATIONS ~~| Mission Bay, CA I Big Slough. TX 1 Tar Landing. NC 10 28/83. PLANKTOTROPHIC POPULATIONS •H Marine Environmental Research Lab, Narragansett Bay, Rl II I I II New Bedford Harbor. MA Tar Landing, NC 2 s/83 Sebastian R. FL Copano Bay. TX 80 NUMBER OF LARVAE PER BROOD 160 180 200 250 30O 350 FIGURE 3. Observed distribution of brood sizes are shown in three lecithotrophic and five planktotrophic Streblospio benedicti populations. adult setae (capillary setae and hooded hooks), but at no time do they exhibit the long swimming setae characteristic of many spionid larvae. Lecithotrophic S. benedicti larvae are competent to settle at 9-12 setigers and generally settle at the time of their release. They may recruit without ever entering the water column. However, in the absence of suitable substrate, larvae may remain planktonic up to 7 days (Fig. 5). Following release from the brood pouch into the water column, larvae appear to derive nutrition from original yolk supplies. Stored yolk was observed to sustain larvae for approximately one week without external sources of food. Planktotrophic S. benedicti larvae differ most noticeably from lecithotrophic forms in the presence of long "swimming" setae, a decreased yolk supply, a functional gut early in development, and a longer planktonic development (Table III). Within 2-3 days after fertilization (at 20°C), small ova develop into larvae with a single set of long serrated setae. Development usually proceeds inside the brood pouch to a 4- setiger stage within 24 hours and to 5-7 setigers within 2-3 more days (Fig. 4D, E, and F). Long serrated setae develop on each segment as they are added. The larvae have fully formed guts at the 4-setiger stage (^250-300 ^m) and if released they begin planktonic feeding. Strong swimming ability and positive phototaxis is evident throughout th
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
