Feeding and nutritional ecology of the sea urchins Echinometra lucunter (Linnaeus, 1758) and Arbacia punctulata (Lamarck, 1816) Echinodermata: Echinoidea): the importance of animal foods

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.Analysis of gut contents of Echinometra lucunter and Arbacia punctulata revealed that A. punctulata consumes significantly greater amounts of animal material--barnacles, mollusks, and bryozoans--than E. lucunter. Where these two species live sympatrically on the South Padre Island jetty, niche partitioning appears to be occurring. Different behavioral modes of feeding by urchins of the same species were demonstrated. The different natural diets of A. punctulata collected from two different locations (South Padre Island jetty and the Port Aransas jetty) can probably be attributed to food availability. Similarly, E. lucunter collected from the South Padre Island rock rubble area ingested more higher-plant material and less algal material than the same species on the nearby jetty. Determination of digestion coefficients of E. lucunter for three different diets showed that absorption of protein was more efficient from invertebrate (crab and squid) material than from algae or mixed food items. Absorption of carbohydrate was highest for the algal diet treatment. Absorption of lipid occurred at nearly the same efficiency for all three diets. Based on the high absorption efficiencies for protein, these results lend support to the idea that the consumption of invertebrate or animal material by urchins may enhance growth and reproductive fitness. Gonad indices calculated at the termination of the feeding experiment indicated that the diets offered were not adequate to maintain or increase gonad weight. Gonad indices tended to drop off after reaching a maximum in urchins with a test diameter size of 5 cm. Field trials of chemoreception showed that E. lucunter exhibited a greater number of successful movements towards food items than A. punctulata. Nocturnal chemoreception of prey items was demonstrated by E lucunter. E. lucunter did not exhibit a preference in the field for tiny one particular food item