Behavioural response to light of the newly hatched phyllosoma larvae of Panulirus longipes cygnus george (crustacea: decapoda: palinuridae)

• Published in: Journal of experimental marine biology and ecology 1972-11, Vol.10 (2), p.105-114
• Main Author: Ritz, D.A.
• Format: Article
• Language: English
• Subjects: Marine; Panulirus longipes cygnus
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/0022-0981(72)90096-2

The threshold level of positive phototaxis and the spectral sensitivity of the newly hatched phyllosoma larvae of the western rock lobster, Panulirus longipes cygnus George have been determined. Larvae swam actively towards a weak white light source (peak wavelength about 510 nm) but the response gradually diminished and disappeared at a threshold level of about 4.4 × 10 −6μW/cm 2. In strong light intensities of the same spectral composition a random response occurred when the intensity exceeded about 4.6 mW/cm 2. Three distinct peaks of sensitivity at about 470 nm, 555 nm and 615 nm, to light of restricted wavelength were evident. It has been estimated that, at threshold intensity in light of 470 nm peak wavelength each ommatidium of the eye receives approximately 235 quanta/sec. These findings suggest that the phyllosoma larvae are extremely well equipped for finding their way to the surface of the sea from great depths and on dark nights in both oceanic (blue) and coastal (green) water. Since these larvae hatch in a coastal environment and are transported into the oceanic circulation during their long planktonic life these properties might have great adaptive significance.