Ivory Towers

Extracting the urine from temporarily blinded lobsters
Have you ever wondered whether a boy lobster and a girl lobster will be able to find each other if they are blindfolded and prevented from urinating into the water of their tank? That very topic was investigated in "Sex recognition and the role of urinary cues in the lobster, Homarus americanus," (by M J Snyder, C Ameyaw-Akumfi and E S Chang, Marine Behavior and Physiology, December 1993), and the answer is that they will.

The paper, according to the abstract on Ovid's PsycLit database, "characterized components of sex recognition by American lobsters through detailed study of videotaped recordings of both intra- and intersexual interactions in temporarily blinded lobsters ... Results suggest that sex recognition occurring over short distances may not rely on visual information." Furthermore, they developed "a method of antennal gland cannulation that allowed for continuous collection of voided urine from individual lobsters in paired interactions away from contact with the seawater." Since mating still occurred, the researchers concluded that "urine is not a source of factors required for lobster sex recognition."

Food, however, causes a lobster more problems, particularly if it is placed on the side of its larger claw. W F Angermeier of Cologne University examined the responses of 18 lobsters to food presented on different sides of their tank. The results, as reported in "Behavioral expression of the asymmetry in lobster claws" (Bulletin of the Psychonomic Society, July 1991), showed that it all depends whether the lobster is left-clawed or right-clawed: "When only one side was baited, all lobsters with the large crusher claw on the left side made more mistakes on the left, and all lobsters with the large crusher claw on the right side made more mistakes on the right. Results indicate that food-related information is perceived more accurately by lobsters when it comes from the contralateral side of the large crusher claw."

Two final results complete our survey of the state of knowledge of lobster behaviour. In "Spatial and temporal coordination during walking in Crustacea" (F Clarac, Trends in Neurosciences, August 1984) reports that a lobster's stride length is invariable whatever speed it walks at. And "An intersegmental reflex between the copulatory swimmerets of the male squat lobster," (WJ Heitler, CM Myers and DP Maitland, Marine Behavior and Physiology, November 1983) reports that the male squat lobster has an intersegmental reflex between its copulatory swimmerets.