156 



Figure 110: Epaulettes and pedicellaria in the pluteus of Echinometra mathaei 



(Onoda, 1936). 

 lep — lower epaulettes; p — pedicellaria; uep — upper epaulettes. 



urchins; in Strongylocentrotids it is 35 |im. On the epaulettes, as also at the 

 base of the ciliated band, beating of the cilia is undulatory (Strathmann, 

 1971). In other species, in place of the epaulettes between the postoral and 

 posterodorsal arms, the integument and corresponding areas of the ciliated 

 band become stretched and vibratile lobes are formed (Figure 111). 



The beating wave of cilia on the epaulettes of strongylocentrotids and 

 lobes of Dendraster is directed toward the median line of the larva. Such an 

 unusual direction of beating possibly counteracts rotation of the larva, created 

 by the beating of the ciliated band (Strathmann, 1971). Neither the cilia of 

 the epaulettes and various lobes nor the cilia of the bands bordering the aboral 

 rod of the pluteus of heart urchins participate in the seizure of food particles; 

 they serve only for locomotion. 



Nervous system and sense organs : The nervous system of the larvae 

 remains unchanged. Pigmentation intensifies on the arms and new pigment 

 centers appear. Especially intensive pigmentation is observed in the region of 

 the stomach, coelom and amniotic sac; the latter appears at this stage (Figure 

 112). 



Attachment apparatus : Settling, searching the substrate, and temporary 

 attachment to it are ensured in the metamorphosing larvae of sea urchins by 

 the five primary plates formed during metamorphosis at the base of the 



