THE CHEMICAL SENSE AND FEEDING BEHAVIOR OF NEREIS VIRENS. SARS

¹ MARINE BIOLOGICAL LABORATORY, WOODS HOLE, MASS

1. Nereis virens is carnivorous, although in the absence of other food it has been observed to feed upon sea lettuce. Under natural conditions it undoubtedly is omnivorous, since Gross has found evidence of the presence of plant food in the digestive tract.

2. Nereis was never observed to leave its burrow when baited with meat of various marine animals, but it may expose all except the posterior segments of its body in reacting to the bait. This does not mean that the worm may not leave its burrow under other circumstances. The animal is highly thigmotactic.

3. There is positive evidence that Nereis depends upon a chemical sense in finding animal food; sight playing little if any part in the act. Currents in the burrow produced by an undulatory body movement are undoubtedly a factor in conveying food stimuli to the sense organs.

4. Nereis shows a marked tendency to extend its body from the burrow in the direction of food, and failing to reach it, to reappear in a new position nearer the source of the stimulating material.