Utilization of lipids during early development of the sea urchin Evechinus chloroticus

Detailed studies of lipid utilization during bivalve development have shown that lipids are important at 2 critical periods: embryogenesis and metamorphosis. Using the Iatroscan TLC/FID system I examined lipid class utilization during development of Evechinus chloroticus to determine whether lipids were also important for an echinoderm at these times. Eggs of E. chloroticus contained 34.41 ng of lipid, primarily polar lipids (52.0%) and triglyceride (29.4%). To determine whether there was a different pattern of lipid utilization between larvae reared in the presence or absence of particulate food, larvae were either fed 6000 cells ml–1 Dunaliella every 2 d or starved. While there was no change in the amount of total, structural or energy storage lipids over time, there was a significant difference in the amount of structural lipids between Fed and Starved treatments. This was related to the continuing development of Fed larvae and cessation of development of Starved larvae at the 4-arm pluteus stage. In both treatments, triglycerides were rapidly utilized from the early 4-arm echinopluteus to the late 4-arm larva with fully developed arms and gut. Another neutral lipid, free fatty acid, accumulated in the 8-arm echinopluteus stage of the Fed larvae. This suggests that lipid stored during the planktonic phase, in combination with the proximate constituents of the larval body, provides the energy for the metamorphic and perimetamorphic periods in echinoderm development. Thus sea urchins, as in bivalves, appear to have 2 critical periods for lipid use during development.