The rudiments of the five arms are present, but the terminal tentacle and tube feet
are not yet visible in the region around the developing juvenile mouth.
The tube feet
have other functions besides registering light.
Anatomy examination covered observation on gonad, pyloric ceca, spine, ambulacral ridge, cardiac stomach, mouth, ring canal, and tube feet
and photographs were displayed in Figure 3.
Ullrich-Luter instead proposed that opsins in the little cavities at the bases of the tube feet
would be shaded enough to detect light direction.
These animals were not sorted by tube feet
color as significant mortality occurred before sorting.
The vascular system runs through each arm, carrying seawater to the tube feet
and causing them to extend and retract as they are filled and emptied.
Light detection is believed to occur in sea urchins within photoreceptor cells in the terminal disc region of their motile tube feet
, within spines, and across the test (Millot, 1954; Ullrich-Lifter et al., 2011).
hexactis and examined the arm that had been attacked, noting movement of tube feet
along the affected arm and looking for radial nerve damage.
This sunflower star has as many as 15,000 tube feet
. They end in small suction cups.
Following metamorphosis from larvae, sea urchins exhibit pentaradial symmetry and develop a hard calcified test from which protrude numerous spines and tube feet
. Within the test is the gastrointestinal tract, male or female gonads, a nervous system, and a water vascular system that controls tube feet
relaxation and extension (Nichols, 1966).
The gobies remind him of small crabs that hide in certain corals and nip the tube feet
of encroaching crown of thorns starfish that can ravage a reef.
The first two pairs of tube feet
appear in each ray of the starfish rudiment, and the adhesive disc appears on the larval body (Fig.