. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ZOOXANTHELLATE EGGS OF CORALS 73. Figure 4. Planula of Pocillnpora verrucosa 24 h after fertilization. (A) Photomicrograph of a fixed planula taken under differential interference optics. The planula is completely ciliated at this stage. (B) Histological section of a planula. Zooxanthellae and lipid droplets are in the endodermal cells. (C-D) Photomicrographs of the body wall of a planula taken under oil immersion. The ectoderm and endoderm are clearly separated by the mesoglea (arrowhead). The ectoderm consists of columnar


. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ZOOXANTHELLATE EGGS OF CORALS 73. Figure 4. Planula of Pocillnpora verrucosa 24 h after fertilization. (A) Photomicrograph of a fixed planula taken under differential interference optics. The planula is completely ciliated at this stage. (B) Histological section of a planula. Zooxanthellae and lipid droplets are in the endodermal cells. (C-D) Photomicrographs of the body wall of a planula taken under oil immersion. The ectoderm and endoderm are clearly separated by the mesoglea (arrowhead). The ectoderm consists of columnar cells, c = ectoderm, g = gastrovascular cavity, m = mouth opening, n = endoderm. Bars = 100 ;xm in (A) and (B), 20 in (C) and (D). thellae and lipid droplets in the blastocoel were surrounded by a small amount of cytoplasm and appeared to be free— that is, detached—from blastomeres in the outer layer (Fig. 3E, F). Spherical embryos with a smooth surface as shown in Figure 2E and F were observed 6 h after fertilization. Ciliated larvae started to swim 8 h after fertilization. The embryos became elliptical and swam spirally by 9-10 h after fertilization. An oral pore was formed by invagination of the epidermis, and a gastrovascular cavity was formed as gastrodermal cells became organized 24 h after fertilization (Fig. 4A, B). At this stage the ectodermal layer—the plan- ula's epidermis—consisted of characteristic columnar cells, and the epidermis and gastrodermis were separated by dis- tinct mesoglea (Fig. 4C, D). Embryos at this stage were typical planulae. Generally, only gastrodermal cells con- tained zooxanthellae, though a few zooxanthellae were ob- served in ectoderm of some planulae. Planulae 48 h old possessed some nematocysts. Discussion Although early development of scleractinians has been described (, Szmant-Froelich et al., 1980, 1985; Bab- cock and Hey ward, 1986; Harrison and Wallace, 1990), this is the first report describing the processes by which


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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology