FEEDING BEHAVIOR OF Nassarius vibex (GASTROPODA: NASSARIIDAE)

Abstract

Many studies on Nassariidae have focused on species that live in the intertidal zone, that are very well adapted to scavenger behavior for presenting an ability of chemoreception at a very long distance. The objectives of this study were to record the time spent by Nassarius vibex feeding on the field, to investigate its correlation with the shell size and to analyze the response time to stimulation by the feeding depending on the duration of hunger under laboratory conditions. Five pieces of fish were placed to serve as bait, and every five minutes, from the time of the bait until 50 minutes later, the number of individuals attracted to these was registered. The early feeding of N. vibex was considered when its proboscis was extended on the bait and end when the animal left the bait. This procedure was repeated for 111 individuals distributed in three days of observation, in January, February and March of 2007. Forty individuals divided into four groups of 10 animals each, which were placed in an tank containing 1 liter of seawater, salinity 30 and constant aeration. At the experiment day 0, food was offered to all groups, thus standardizing the level of hunger and every seven days a different group was fed again so that each group fasted for different periods time. In the field, N. vibex had a six-minute period of food consumption, with 76% of individuals feeding for up to 8 minutes. There was no correlation between feeding time and shell length. In the laboratory, the response time to the presence of food depended on the duration of hunger, with the animals that fasted for longer periods responding more quickly to the presence of food.