EFFECT OF NUTRITION ON THE EXCRETION RATE OF SOLUBLE NITROGENOUS PRODUCTS OF LUIDIA-CLATHRATA (SAY) (ECHINODERMATA, ASTEROIDEA)

1. 1. Groups of Luidia clathrata were fed maintenance level diets of Donax variabilis (50% protein by dry weight) or Penaeus duorarum (80% protein) or were starved. 2. 2. The NH4+ excretion rates for all treatments increased from 6.06 ± 2.55 to 14.39 ± 4.31 μg NH4+ - N/g dry wt per hr after 20 days. 3. 3. The urea excretion rate for all treatments was 1.25 ± 3.39 μg urea-N/g dry wt per hr for 56 days. 4. 4. The pyloric caecum index (percentage of wet body weight) decreased 16.5 and 73.4%, for Donax variabilis-fed and starved sea stars, respectively. The pyloric caecum index of Penaeus duorarum-fed sea stars increased 81.5%. The protein level of the pyloric caeca was 47.00 ± 4.14% of the dry weight for the fed animals and 37% for the starved animals. 5. 5. Increased NH4+ excretion rates with starvation or presumed maintenance diets appear to be due to tissue catabolism. © 1979.