HUANG, H.-D.; RITTSCHOF, D.; JENG, M.-S.; Duke Univ.; Duke Univ.; Academia Sinica, Taiwan: Visual Orientation of the Symbiotic Snapping Shrimp Synalpheus demani

Visually cues play an important role in crustacean shelter-seeking behavior. We hypothesize that Synalpheus demani, an obligate crinoid-dwelling snapping shrimp, uses visual cues in host location. We tested shrimp response to rectangular visual targets that subtended 10&deg, 30&deg, 90&deg, 180&deg, and 270&deg in a circular arena in background sea water and in sea water containing host odor. In background sea water, S. demani oriented to solid visual targets of 90&deg and larger, and avoided the 30&deg target. The former response is interpreted as generalized refuge-seeking behavior, and the latter response as predator-avoidance. Shrimp oriented to large visual targets in sea water and host odor. Avoidance of small targets was reduced in the presence host odor. S. demani oriented to 90&deg patterned (vertical and horizontal stripes, and checker board) targets as to the 90&deg solid target, but they did not orient when to 270&deg patterned targets. This was interpreted as positive scototaxis, which is common in many crustaceans. Thus we conclude that visual orientation of S. demani is similar to that of free-living snapping shrimp. S. demani integrate chemical cues to facilitate their visual orientation in host location.