Spectral light sensitivity of isolated chromatophores of the sea urchin, Centrostephanus longispinus

Forming sea urchin barrens from the inside out: an alternative pattern of overgrazing

“…Our detailed observations of the nocturnal behaviour of Centrostephanus rodgersii were consistent with previous in situ observations (Jones & Andrew 1990) and evidence of light sensitivity in other diadematid sea urchins (Millott 1954, 1968, Gras & Weber 1983. Peaks in the velocity of their movement at the end of the night were most pronounced on widespread flat-rock barrens, where the dawn appeared to trigger a short burst of rapid and directional movement toward micro-crevices (the only available shelter on otherwise featureless flat-rock surfaces) in browsing individuals.…”

“…Each monitored reef was characterised by moderate topographic relief reaching a maximum depth of 12 to 16 m, with a macroalgal canopy (where present) dominated by the laminarian Ecklonia radiata and fucoid Phyllospora comosa. Movement was recorded over 15 different nights with time-lapse sequences using Nikon D200 digital SLR and Pentax Optio W80 digital compact cameras equipped with red lighting to minimise disturbance of sea urchins throughout the nocturnal cycle (see Millott 1968, Gras & Weber 1983. Each sampling occasion was spatially independent, with a different area of reef and different sea urchins monitored in each of the photographic sequences.…”

Forming sea urchin barrens from the inside out: an alternative pattern of overgrazing

“…Our detailed observations of the nocturnal behaviour of Centrostephanus rodgersii were consistent with previous in situ observations (Jones & Andrew 1990) and evidence of light sensitivity in other diadematid sea urchins (Millott 1954, 1968, Gras & Weber 1983. Peaks in the velocity of their movement at the end of the night were most pronounced on widespread flat-rock barrens, where the dawn appeared to trigger a short burst of rapid and directional movement toward micro-crevices (the only available shelter on otherwise featureless flat-rock surfaces) in browsing individuals.…”

“…Each monitored reef was characterised by moderate topographic relief reaching a maximum depth of 12 to 16 m, with a macroalgal canopy (where present) dominated by the laminarian Ecklonia radiata and fucoid Phyllospora comosa. Movement was recorded over 15 different nights with time-lapse sequences using Nikon D200 digital SLR and Pentax Optio W80 digital compact cameras equipped with red lighting to minimise disturbance of sea urchins throughout the nocturnal cycle (see Millott 1968, Gras & Weber 1983. Each sampling occasion was spatially independent, with a different area of reef and different sea urchins monitored in each of the photographic sequences.…”

Sea urchin tube feet are photosensory organs that express a rhabdomeric-like opsin and PAX6

“…The spectral sensitivity of these photoreceptors peaks between 530 and 550 nm [11], which points towards the involvement of a specific chromophore or pigment. In this study, it was also suggested that the pigments associated with echinoderm photoreceptors might be carotenoids [11], while another study on the sea urchin Centrostephanus longispinus shows peak sensitivity of its isolated chromatophores between 430 and 450 nm based on an action spectrum of chromatophore contraction and expansion [15]. In this latter case, however, the chromatophores were not functionally linked to the nervous system and were not interpreted as being involved in photoreception [15].…”

Forming sea urchin barrens from the inside out: an alternative pattern of overgrazing

“…Our detailed observations of the nocturnal behaviour of Centrostephanus rodgersii were consistent with previous in situ observations (Jones & Andrew 1990) and evidence of light sensitivity in other diadematid sea urchins (Millott 1954, 1968, Gras & Weber 1983. Peaks in the velocity of their movement at the end of the night were most pronounced on widespread flat-rock barrens, where the dawn appeared to trigger a short burst of rapid and directional movement toward micro-crevices (the only available shelter on otherwise featureless flat-rock surfaces) in browsing individuals.…”

“…Each monitored reef was characterised by moderate topographic relief reaching a maximum depth of 12 to 16 m, with a macroalgal canopy (where present) dominated by the laminarian Ecklonia radiata and fucoid Phyllospora comosa. Movement was recorded over 15 different nights with time-lapse sequences using Nikon D200 digital SLR and Pentax Optio W80 digital compact cameras equipped with red lighting to minimise disturbance of sea urchins throughout the nocturnal cycle (see Millott 1968, Gras & Weber 1983. Each sampling occasion was spatially independent, with a different area of reef and different sea urchins monitored in each of the photographic sequences.…”

Sea urchin tube feet are photosensory organs that express a rhabdomeric-like opsin and PAX6

“…The spectral sensitivity of these photoreceptors peaks between 530 and 550 nm [11], which points towards the involvement of a specific chromophore or pigment. In this study, it was also suggested that the pigments associated with echinoderm photoreceptors might be carotenoids [11], while another study on the sea urchin Centrostephanus longispinus shows peak sensitivity of its isolated chromatophores between 430 and 450 nm based on an action spectrum of chromatophore contraction and expansion [15]. In this latter case, however, the chromatophores were not functionally linked to the nervous system and were not interpreted as being involved in photoreception [15].…”

Forming sea urchin barrens from the inside out: an alternative pattern of overgrazing

“…Our detailed observations of the nocturnal behaviour of Centrostephanus rodgersii were consistent with previous in situ observations (Jones & Andrew 1990) and evidence of light sensitivity in other diadematid sea urchins (Millott 1954, 1968, Gras & Weber 1983. Peaks in the velocity of their movement at the end of the night were most pronounced on widespread flat-rock barrens, where the dawn appeared to trigger a short burst of rapid and directional movement toward micro-crevices (the only available shelter on otherwise featureless flat-rock surfaces) in browsing individuals.…”

“…Each monitored reef was characterised by moderate topographic relief reaching a maximum depth of 12 to 16 m, with a macroalgal canopy (where present) dominated by the laminarian Ecklonia radiata and fucoid Phyllospora comosa. Movement was recorded over 15 different nights with time-lapse sequences using Nikon D200 digital SLR and Pentax Optio W80 digital compact cameras equipped with red lighting to minimise disturbance of sea urchins throughout the nocturnal cycle (see Millott 1968, Gras & Weber 1983. Each sampling occasion was spatially independent, with a different area of reef and different sea urchins monitored in each of the photographic sequences.…”

Sea urchin tube feet are photosensory organs that express a rhabdomeric-like opsin and PAX6

“…The spectral sensitivity of these photoreceptors peaks between 530 and 550 nm [11], which points towards the involvement of a specific chromophore or pigment. In this study, it was also suggested that the pigments associated with echinoderm photoreceptors might be carotenoids [11], while another study on the sea urchin Centrostephanus longispinus shows peak sensitivity of its isolated chromatophores between 430 and 450 nm based on an action spectrum of chromatophore contraction and expansion [15]. In this latter case, however, the chromatophores were not functionally linked to the nervous system and were not interpreted as being involved in photoreception [15].…”