The painted shrimp Hymenocera picta forms stable pairs, based on individual recognition at a distance by chemical cues.This was tested in a Y-maze. The receptors responsible for the olfactorial recognition are sensillae on the antennules. Their fine structure and cleaning procedure have been analyzed. We identified pairs sociometrically by the partners' intimate proximity. Partner fidelity without sexual fidelity is part of the male reproductive strategy. Single individuals perform about twice as many observable movements as paired individuals. The marine shrimp Hymenocera picta feeds on live starfish, be it on autotomized arms or on whole starfish. These are turned upside-down and then have their epidermis pierced and their inner tissues pulled out and eaten. Pair members do not cooperate for feeding.    © Seibt

Experimental setup

a) A pair of the monogamous painted shrimp feeding on live starfish

b) Choice situation in a submerged Y/maze. arrows indicate water-currents: choosing individual starts from hindmost lower tunnel: test individuals locked in left and right upper chambers

Performance

A: One choosing male in the Y-maze vacillated between smells of two unknown females 42 and 44 Thereafter the male was free to join with one of these and some more females in a large tank for three weeks. He stayed mostly with female 42 B: Now the choosing male in the Y-maze consistently prefers the smell of female 42

Results
Individuals are able to recognize one another over long distance by chemical cues only.
A partner's smell has to be learned.

Literature
Seibt, Uta & Wickler, Wolfgang 1981: Paarbildung und Paarbindung bei Krebsen. Biologie in unserer Zeit 11, 161-168

Wickler, Wolfgang & Seibt, Uta 1981: Monogamy in crustacea and man. Zeitschrift für Tierpsychologie 57, 215-234.

Seibt, Uta 1980: Soziometrische Analyse von Gruppen der Garnele Hymenocera picta. Zeitschrift für Tierpsychologie 52, 321-330

Seibt, Uta & Wickler, Wolfgang 1979: The biological significance of the pair-bond in the shrimp Hymenocera picta. Zeitschrift für Tierpsychologie 50, 166-179

Wasserthal, L. T. & Seibt, Uta 1976: Feinstruktur, Funktion und Reinigung der antennalen Sinneshaare der Garnele Hymenocera picta. Zeitschrift für Tierpsychologie 42, 186-199

Seibt, Uta 1974: Mechanismen und Sinnesleistungen für den Paarzusammenhalt bei der Garnele Hymenocera picta Dana. Zeitschrift für Tierpsychologie 35, 337-351

Seibt, Uta 1973: Sense of smell and pair-bond in Hymenocery picta. Micronesia 9, 231-236

Seibt, Uta 1973: Die beruhigende Wirkung der Partnernähe bei der monogamen Garnele Hymenocera picta. Zeitschrift für Tierpsychologie 33, 424-427

Seibt, Uta & Wickler, Wolfgang 1972: Individuen-Erkennen und Partnerbevorzugung bei der Garnele Hymenocera picta Dana. Naturwissenschaften 59, 40-41

Wickler, Wolfgang & Seibt, Uta 1972: Über den Zusammenhang des Paarsitzens mit anderen Verhaltensweisen bei Hymenocera picta Dana. (Eine Erörterung des Bindungstriebes und der Konvergenz von Trieben). Zeitschrift für Tierpsychologie 31, 163-170

Wickler, Wolfgang & Seibt, Uta 1970: Das Verhalten von Hymenocera picta Dana, einer Seesterne fressenden Garnele (Decapoda, Natantia, Gnathophyllidae). Zeitschrift für Tierpsychologie 27, 352-368

Films
Seibt, Uta 1973: Hymenocera picta (Gnathophyllidae) - Häutung. Encyclopaedia Cinematographica, Göttingen, E 1991/1973

Wickler, Wolfgang & Seibt, Uta 1972: Hymenocera picta (Gnathophyllidae) - Erbeuten des Stachelseesternes Acanthaster planci. Encyclopaedia Cinematographica, Göttingen, E 1795/1972

Seibt, Uta 1971: Hymenocera picta (Gnathophyllidae) - Kopulation. Encyclopaedia Cinematographica, Göttingen, E 1725/1971

Wickler, Wolfgang & Seibt, Uta 1971: Hymenocera picta (Gnathophyllidae) - Fressen eines Seesternes. Encyclopaedia Cinematographica, Göttingen, E 1724/1971

Additional Literature
Wickler, Wolfgang 1973: Biology of Hymenocera picta Dana. Micronesia 9, 225-230.