The Neptune’s Cup sponge in Singapore
the base of the stalk. The oval disk has a diameter of 38 cm
on the long side and 28 cm on the short side, with a depth of
5 cm. Rim of disk is not level (Fig. 5). Thickness of disk is
approximately 1.5 cm at the rim, becoming gradually thicker
towards the center. Surface of disk is covered with papillae.
Only oscular papillae are present on the upper surface of the
disk, and most papillae are 1-2 mm apart from each other.
These oscular papillae are circular in outline with a diameter
ranging between 1-3 mm and are typically 0.1 mm in height
(Fig. 6A). Ostial papillae are found only on the underside of
the disk and cover the entire undersurface of the disk. These
ostial papillae are typically 1-2 mm apart from each other,
and they extend downward to the upper part of the stalk.
The ostial papillae are 3-5 mm in diameter and 2-3 mm in
height (Fig. 6B). The stalk is 13 cm in height, cylindrical in
shape, with a diameter of 4 cm at the middle of the stalk.
The rooting processes are about 1 cm in diameter, and these
are fi lled with materials from the surrounding substratum,
consisting mainly of sand, mollusc shells, coral rubble and
foraminifera.
Skeleton. — Consists of a thick cortical skeleton, 2.2 mm
in width, with numerous thick branching and anastomosing
spicule tracts (1-1.5 mm) (Fig. 7A). The ectosomal skeleton
comprises of dense tylostyle palisade supported by dense