Cleaning symbiosis between shrimp (Hippolytidae) and moray eels (Muraenidae): primitive or advanced

Abstract

This study focuses on the cleaning behavior of Lysmata wurdemanni, a temperate Atlantic species, and L. grabhami, a tropical Atlantic species, in relation to Gymnothorax meleagiis, an Indo-Pacific moray eel. The following hypothesis was tested: All cleaner shrimp do not respond to clients in the same manner; even shrimp of the same genus respond differently in cleaning situations. Shrimp behavior with morays was observed for general behaviors: approach host, cleaning/touching host, stationary, and moving/swimming; as well as for specific parts cleaned, mouth, head, trunk, and tail. The shrimp also were observed in this manner in the presence of a control species, Fundulus grandis (a killifish). General eel behavior: posed, headsweep, stationary, moving in rocks, and emerged from rocks; was noted for eels alone, with shrimp and during cleaning/touching. The difference in behavior between L. wurdemanni and L. grabhami was compared. L.wurdemanni does not appear to be an obligate cleaner like some of its tropical counterparts. Unlike obligate cleaners it does not depend on cleaning alone to obtain nourishment. Much of its time is spent picking at the substrate in search of food and cleaning its antennae, which pick up chemical cues. Comparisons between this behavior and that of L. grabhami have shown that L. wurdemanni is not as sophisticated in its cleaning behavior. It tends to be quite haphazard in approaching and cleaning/touching the host. L. grabhami does not depend on cleaning as its sole source of nourishment either. However, it does spend much more of its time approaching or cleaning/touching the host than L. wurdemanni.