Orientation in sandhoppers from Italian populations: Have they magnetic orientation ability?

Abstract

Given the widespread evidence of magnetic orientation in talitrids from Atlantic and Equatorial populations, it seemed interesting to test this ability in Mediterranean ones. This paper reports the results of orientation tests on wild caught and laboratory‐born individuals from five Italian Tyrrhenian and Adriatic populations of Talitrus saltator (Montagu, 1808) and an Adriatic one of Talorchestia deshayesei (Audouin, 1826). Tests were carried out in absence of visual cues with the natural magnetic field or with an artificially rotated one, and with the sun reference experimentally in conflict with the magnetic one (by block‐shifting the animals or rotating the magnetic field). On the whole, the tests failed to show magnetic orientation ability, except a weak non‐visual orientation tendency in laboratory‐born individuals of two Tyrrhenian populations. When the magnetic reference and the solar one were in conflict, the latter prevailed both for laboratory‐born and wild caught individuals. A tentative phylogenetic interpretation of the magnetic orientation in talitrids is given.

Key words:

• Amphipoda
• Talitridae
• Sandhoppers
• Magnetic orientation