Green Boring Sponge

Cliona caribbaea Carter

Cliona caribbaea Carter. 1882:346–347, fig. 26.—Topsent, 1889:49.

Cliona viridis.—Topsent, 1900:84–98 (in part), pl 3: fig. 3d.

Cliona viridis var. caribbaea.—Topsent, 1932:563–565, fig. 5.

DESCRIPTION.—Ectosome: The papillae (Figure 2a) exhibit basically a greenish color. Specimens can be grayish ocher or dark brown with a green tinge; others are light olive or yellow olive; the majority is of dark olive color. In alcohol, the chlorophyll of the symbiotic algae dissolves and leaves the papillae gray. Dry specimens are grayish ocher. The papillae are circular to oval, and are usually spaced 1–5 mm from each other, but they have a strong tendency to fuse. Their diameters range from 0.5 × 0.5 mm to 4.0 × 3.7 mm (2.4 × 1.9 mm). Fused complex papillae are 3.0 × 1.5 mm-22.0 × 9.0 mm (7.2 × 3.0 mm). Very seldom fusion goes as far as to form continuous incrustations, to the extent of 2–3 cm2. The following observations can only be made on undisturbed specimens underwater. The edges of the papillae are raised to about 1 mm above the substratum; their center is depressed. Some of the larger ones bear one or, at most, two oscula with a raised rim (1–2 mm), which is always lighter in color (yellowish) than the papilla. Diameter of the osculum depends on the activity of the animal; it can reach 1.2 mm. Ostia are present on all papillae and can be opened to 0.3 mm. Intracellular symbiotic algae (zooxanthellae) (Figure 2f) are packed in rows between the perpendicular spicule strands. They are spherical and measure 8–10 μm in diameter. They decrease in number with distance from the papillary surface. There is also a well-developed connective tissue with numerous fusiform contractile cells, which account for the strong contractibility of the papillae.

Choanosome: Breaking up the substratum exposes sponge tissue of rich yellow ocher color that turns to pale gray in alcohol, but changes little upon drying. The tissue fills the ill-defined, irregularly elongate chambers (Figure 2b) except for the major excurrent canals, measuring 0.5–1.0 mm in diameter. The chambers are interconnected by tissue strands of 0.1–1.5 mm. Interstitial spaces in very porous substrata are also infiltrated. Irregular or spindle-shaped cells, 24 × 7 μm-30 × 10 μm, occur in small accumulations. They contain 1 μm basophilic granules (gray cells). Some specimens collected in January contained egg cells and sperm cysts in various stages of development. Choanocyte-chambers measure 30–35 μm.

Excavations: Single papillary perforations (Figure 2c) measure 0.5–3.2 mm (1.5 mm). Chambers start at 0.5–2.0 mm under the substratum surface. The chambers (Figure 2d) are irregular, ragged, and frequently fused, particularly in porous substrata. They measure approximately 1.9–7.0 mm × 1.3–2.9 mm (4.0 mm × 2.0 mm) if they are well defined. There are 6 to at least 15 foramina per chamber, which are approximately circular and 0.2–1.2 mm (0.5 mm) in diameter. The thickness of the separating walls varies between 0.2 and 1.0 mm. Excavations reach 15 mm into the substratum.

Spicules: Tylostyles occur everywhere, but show orientation perpendicular to the substratum only in the papillae (Figure 2e). Spirasters are rare or absent in the papillae, moderately abundant in the choanosome. Tylostyles (Figures 3a–d, 4a) are straight or slight bent. The point is sharp and gradually tapering from the middle of the spicule. The heads are well set off and usually spheroid. If they are ovoid, the longer axis of the head tends to be perpendicular to the axis of the shaft. Deformations of the heads are common, but rarely are there annular swellings behind them on the shaft. The spirasters (Figures 3c, d, 4b, c) are very delicate and easily overlooked. Under the light microscope they appear as finely spined wavy lines, the majority with 4–7 bends. Some are straight or W-shaped.

Spicule dimensions (in μm): Tylostyles, length × width: 204.1–410.0 × 2.6–8.1 (319.0 × 6.0). Neck width: 1.5–7.4 (4.6). Head length × width: 7.4–13.7 × 7.0–14.8 (9.7 × 10.3). Spirasters, length × width (including spines): 9.6–38.4 × 0.8–3.0 (32.8 × 1.8). Spine width: not resolvable by light. Number of spines: 18–50 + (40 +). Number of bends. 3–10 (5.9).

DISTRIBUTION.—With certainty only tropical western Atlantic.