Feeding history shapes food handling behaviors of larval urchin Heliocidaris crassispina

Food quantity and quality affect larval growth and survival, and in turn population dynamics of many marine invertebrates. However, few studies have addressed how feeding history affects larval ability to manipulate their food. Here, we focus on the larvae of an ecologically important sea urchin, Heliocidaris crassispina, which have elongated ciliated arm rods for particle capture. Larvae were reared with either full or halved food ration to study the effect of chronic starvation. Individuals were also fasted for different durations to assess the effect of short-term starvation. We also investigated the role of physical contact in food handling by feeding the larvae with algal-sized microplastics that had no nutritional value. When kept in environment devoid of food for 24 hours or more, 6-arm larvae filled up their stomachs significantly faster than those that were fasted for 4 hours, regardless of their previous exposure to microplastics. Larvae reared on a half-food, half-plastic beads diet held onto the plastic particles collected in their stomachs longer than their counterparts fed only with algae. Our study illustrated that food handling in these small planktonic individuals is a highly dynamic process: both long term and short term feeding history could shape subsequent particles handling, and consequently, efficiency of nutrient acquisition.