164 



Figure 118: Aboral view of the sand dollar, 

 anp — anal plate; ap ( 1 , 2) — additional plates; m — madreporite; op ( 1 , 2, 3, 4, 5) — ocular 



plates. 



section of the definitive intestine, describing a loop, and the larval intestine 

 produces a counterloop in the definitive intestine. The definitive anus opens 

 again (Figure 122). 



As in sea stars, the fiinction of respiration is passed on to the definitive 

 epithelium and transport of metabolites to the hemal/perihemal systems and 

 visceral coelom, while excretion of products is passed on to the coelomocytes. 



Locomotion : One of the most important functions of the larval ciliated 

 band is locomotion. During metamorphosis the ciliated band is replaced by 

 a new — the embulacral — system, specialized for performing this function. 



