The Biology of Lytechinus Variegatus

L. variegatus is an abundant urchin along the southeastern coast of the United States. It feeds largely on Thalassia, and is eaten by various gastropods and birds. Gonads develop at a test diameter of about 40 mm and at an age of about one year. The growth rate shows a negative correlation with temperature. Spawning occurs throughout the summer, at Miami, but is briefer in Bermuda where it also exhibits a lunar rhythm. Following an unusually cold winter in Miami, a large proportion were protandrous hermaphrodites and had an unusual test shape. Except in the oldest urchins, tissue production is 100 - 200 per cent in 30 days. A tentative estimate of food requirements and efficiency is given.