. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 50 CLARK ET AL. 10. FIGURE 10. Digestive gland cell from 4-week-starved C. lilianae. PI, P2—electron dense plastids; Py—pyrenoid (note low density); VP—vesiculated plastid; inset—enlargement of vesiculated plastid. highly vesicularized plastids, though outer membranes were still intact and thy- lakoids were recognizable in some plastids. Thylakoids were electron dense, plas- toglobuli were indistinct, and some pyrenoids were electron transparent. Vacuoles enclosed most plastids. The cytoplasm contained numerous electron-dens
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 50 CLARK ET AL. 10. FIGURE 10. Digestive gland cell from 4-week-starved C. lilianae. PI, P2—electron dense plastids; Py—pyrenoid (note low density); VP—vesiculated plastid; inset—enlargement of vesiculated plastid. highly vesicularized plastids, though outer membranes were still intact and thy- lakoids were recognizable in some plastids. Thylakoids were electron dense, plas- toglobuli were indistinct, and some pyrenoids were electron transparent. Vacuoles enclosed most plastids. The cytoplasm contained numerous electron-dense bodies, somewhat smaller than intact plastids. These may have been final stages of plastid degeneration. Functional morphology Abundant saccate digestive diverticula almost completely fill the cerata and tail of C. lilianae. A pericardial vein complex occurs at the bases of the cerata (not shown). A dense layer of cilia covers the ceratal surfaces. These cilia create a strong circulation over ceratal surfaces and the pericardial network (Fig. 5C, D). This morphology differs from the flattened parapodial arrangement of the elysiids, but is functionally similar. The internal branching of the diverticula creates a large area for storage of plastids, and the cerata provide a large area for light absorption and gas exchange. The arrangement of cerata, cilia, and pericardial veins probably functions as a "negative gill" (for uptake of CO2 and release of O2), as in the elysiids (Stirts and Clark, 1980). These apparent adaptations for gas exchange suggest that CO2 transport strongly limits symbiotic photosynthesis. The effect of light on photosynthetic rate (Fig. 4) was rather weak at all but the lowest irradiance rates, suggesting that some other factor is limiting. The irradiance effect was measured near the thermal optimum, so CO2 is the most probable limiting factor. Under optimal conditions,. Please note that these images are extracted from scanned page images
Size: 1909px × 1309px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
