193 



Figure 145: Echinocardium cordatum. Pluteus II stage. 

 A - structure of the larval skeleton; B — connection of the anterolateral, posterodorsal and 



postoral rods. 



da — dorsal arch; asp — aboral spicule 



Remaining legend same as in Figure 107. 



cordatum have neither epaulettes, nor vibratile lobes, nor pedicellariae. The 

 bright red qolor of the larva is retained in all the stages of development. The 

 arms of a fiilly formed larva are very long and slender and the body is short. 

 The length of the pluteus III stage is 2 mm (Figure 146). 



Ecology 



Early larvae of £■. cordatum usually appear in Vostok Bay in the last 10 

 days of June when the water temperature in the surface layer is 16.5°C. They 

 are found in maximum numbers in the last ten days of July, completely 

 disappearing from the plankton by July end. In favorable years, larvae of E. 

 cordatum are seen again in the middle ten days of September when the water 

 temperature in the surface layer drops to 17°C and stays at this level for two- 

 three weeks. Such a situation was observed, for instance, in 1970-1971. 



According to the literature, reproduction of E. cordatum is observed off 

 the coast of Scotland from the end of May to mid-September (McBride, 

 1914), on the Isle of Man in the Irish Sea from June to early November 



