Neurophysiological characterization of the photoreceptor system in a brittlestar, Ophiocoma wendtii (Echinodermata: Ophuroidea)

Whole-body photoreceptor networks are independent of ‘lenses’ in brittle stars

“…Although our findings contest the interpretation of the EPTs as microlenses in Ophiocoma, they are still compatible with the electrophysiological studies of Cobb & Hendler [13]. They demonstrated increasing photosensitivity correlating with increasing loss of arm tissue, bleaching EPTs and dermal tissue, including chromatophores, until the nerve bundles beneath each EPT were affected.…”

“…In addition, functions besides photoreception have now been described for several r-opsins in some arthropods and vertebrates [46]. However, the Sp-Op4-reactive cells we interpret as photoreceptor candidates conform to previous descriptions of receptor morphology and r-opsin expression in other ophiuroids, are positioned within the EPT-chromatophore layer in line with Hendler & Cobb [13], are highly numerous, and represent the only candidates identified in any study in over 30 years. We propose it is highly likely that they are responsible for photosensitivity and corresponding behaviours in Ophiocoma.…”

Whole-body photoreceptor networks are independent of ‘lenses’ in brittle stars

“…Although our findings contest the interpretation of the EPTs as microlenses in Ophiocoma, they are still compatible with the electrophysiological studies of Cobb & Hendler [13]. They demonstrated increasing photosensitivity correlating with increasing loss of arm tissue, bleaching EPTs and dermal tissue, including chromatophores, until the nerve bundles beneath each EPT were affected.…”

“…In addition, functions besides photoreception have now been described for several r-opsins in some arthropods and vertebrates [46]. However, the Sp-Op4-reactive cells we interpret as photoreceptor candidates conform to previous descriptions of receptor morphology and r-opsin expression in other ophiuroids, are positioned within the EPT-chromatophore layer in line with Hendler & Cobb [13], are highly numerous, and represent the only candidates identified in any study in over 30 years. We propose it is highly likely that they are responsible for photosensitivity and corresponding behaviours in Ophiocoma.…”

Extraocular Vision in a Brittle Star Is Mediated by Chromatophore Movement in Response to Ambient Light

“…The brittle star Ophiocoma wendtii is a focal species in extraocular vision research; it is highly light averse and has an extensive dispersed photoreceptor network [4,9,21,22] within skeletal pores surrounding calcite structures previously interpreted as microlenses [8,21], associated with light-responsive chromatophores. Alongside three congenerics (cf.…”

Designing efficient microlens arrays: lessons from Nature

“…The behavior of O. wendtii suggests that the transmitted light signal is tuned to match the sensitivity level of the neural bundle and to optimize the reception. 18 The intensity-adjustment function of the chromatophore cells as well as the involvement of the sub-lens nerve bundles in photoreception (as opposed to a 'diffuse' dermal reception) were corroborated by neurophysiological [27][28][29] data. Cobb and Hendler studied the reaction of O. wendtii to light stimuli by direct recording from the nerve cord in brittlestar arms.…”

Whole-body photoreceptor networks are independent of ‘lenses’ in brittle stars

“…Although our findings contest the interpretation of the EPTs as microlenses in Ophiocoma, they are still compatible with the electrophysiological studies of Cobb & Hendler [13]. They demonstrated increasing photosensitivity correlating with increasing loss of arm tissue, bleaching EPTs and dermal tissue, including chromatophores, until the nerve bundles beneath each EPT were affected.…”

“…In addition, functions besides photoreception have now been described for several r-opsins in some arthropods and vertebrates [46]. However, the Sp-Op4-reactive cells we interpret as photoreceptor candidates conform to previous descriptions of receptor morphology and r-opsin expression in other ophiuroids, are positioned within the EPT-chromatophore layer in line with Hendler & Cobb [13], are highly numerous, and represent the only candidates identified in any study in over 30 years. We propose it is highly likely that they are responsible for photosensitivity and corresponding behaviours in Ophiocoma.…”

Extraocular Vision in a Brittle Star Is Mediated by Chromatophore Movement in Response to Ambient Light

“…The brittle star Ophiocoma wendtii is a focal species in extraocular vision research; it is highly light averse and has an extensive dispersed photoreceptor network [4,9,21,22] within skeletal pores surrounding calcite structures previously interpreted as microlenses [8,21], associated with light-responsive chromatophores. Alongside three congenerics (cf.…”

Designing efficient microlens arrays: lessons from Nature

“…The behavior of O. wendtii suggests that the transmitted light signal is tuned to match the sensitivity level of the neural bundle and to optimize the reception. 18 The intensity-adjustment function of the chromatophore cells as well as the involvement of the sub-lens nerve bundles in photoreception (as opposed to a 'diffuse' dermal reception) were corroborated by neurophysiological [27][28][29] data. Cobb and Hendler studied the reaction of O. wendtii to light stimuli by direct recording from the nerve cord in brittlestar arms.…”

Whole-body photoreceptor networks are independent of ‘lenses’ in brittle stars

“…Although our findings contest the interpretation of the EPTs as microlenses in Ophiocoma, they are still compatible with the electrophysiological studies of Cobb & Hendler [13]. They demonstrated increasing photosensitivity correlating with increasing loss of arm tissue, bleaching EPTs and dermal tissue, including chromatophores, until the nerve bundles beneath each EPT were affected.…”

“…In addition, functions besides photoreception have now been described for several r-opsins in some arthropods and vertebrates [46]. However, the Sp-Op4-reactive cells we interpret as photoreceptor candidates conform to previous descriptions of receptor morphology and r-opsin expression in other ophiuroids, are positioned within the EPT-chromatophore layer in line with Hendler & Cobb [13], are highly numerous, and represent the only candidates identified in any study in over 30 years. We propose it is highly likely that they are responsible for photosensitivity and corresponding behaviours in Ophiocoma.…”

Extraocular Vision in a Brittle Star Is Mediated by Chromatophore Movement in Response to Ambient Light

“…The brittle star Ophiocoma wendtii is a focal species in extraocular vision research; it is highly light averse and has an extensive dispersed photoreceptor network [4,9,21,22] within skeletal pores surrounding calcite structures previously interpreted as microlenses [8,21], associated with light-responsive chromatophores. Alongside three congenerics (cf.…”

Designing efficient microlens arrays: lessons from Nature

“…The behavior of O. wendtii suggests that the transmitted light signal is tuned to match the sensitivity level of the neural bundle and to optimize the reception. 18 The intensity-adjustment function of the chromatophore cells as well as the involvement of the sub-lens nerve bundles in photoreception (as opposed to a 'diffuse' dermal reception) were corroborated by neurophysiological [27][28][29] data. Cobb and Hendler studied the reaction of O. wendtii to light stimuli by direct recording from the nerve cord in brittlestar arms.…”