Studies on the Biology of the Tropical Sea Urchins, Echinometra Lucunter and Echinometra Viridis

The sea urchins, Echinometra lucunter (Linnaeus) and E. viridis A. Agassiz, are found in the same habitat on Margot Fish Shoal, a “patch” reef off the Florida Keys. The former species, however, is more widely distributed off southeastern Florida than the latter. In addition to the patch reef environment, E. lucunter also is found commonly on some rocky, inshore areas. In both species, growth of the gonads occurred during spring and summer. Spawning probably occurred in late summer or early fall. There was some indication that gametogenesis and spawning began slightly later in 1965 for E. viridis than for E. lucunter. Although individuals of E. lucunter from different habitats manifested a similar reproductive cycle, relative growth of the gonads and size of the test were greater in inshore areas than on offshore patch reefs. Young specimens of E. lucunter were found in large numbers on several sites in the summer of 1965, and in fewer numbers in the summer of 1966. These urchins failed to survive to sexual maturity on the outer reefs.