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

Sumner‐Rooney, Lauren; Kirwan, John D.; Lowe, Elijah K.; Ullrich-Lüter, Esther

doi:10.1016/j.cub.2019.11.042

Cited by 28 publications

(31 citation statements)

References 55 publications

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“…Los microlentes observados en las placas dorsales de los brazos habían sido reportados con anterioridad para especies de la familia Ophiocomidae pero no para O. alexandri (Sumner-Rooney, Rahman, Sigwart & Ullrich-Lüter, 2018). Estos microlentes o trabéculas periféricas expandidas (EPT) están asociados a paquetes de fibras nerviosas y cromatóforos; formando un sistema fotorreceptor (Hendler & Byrne, 1987) y en los últimos años se han realizado pruebas de inmunohistoquímica, histología y microtomografía de sincrotrón para conocer la función de dichas estructuras (Sumner-Rooney et al, 2018;Sumner-Rooney, Kirwan, Lowe & Ullrich-Lüter, 2020). Sumner-Rooney et al (2020) reconstruyeron modelos de los fotorreceptores de Ophiomastix wendtii (Müller & Troschel, 1842) y Ophiocomella pumila (Lütken, 1856) (anteriormente clasificadas bajo el género Ophiocoma), donde concluyeron que aunque las dos especies tienen EPT esféricos en las placas dorsales de los brazos, solo O. wendtii posee una visión extraocular producida por los cromatóforos.…”

Section: Discussionunclassified

Morfología y microestructura interna de la estrella quebradiza Ophiocomella alexandri (Echinodermata: Ophiocomidae)

2021

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Introducción: Ophiocomella alexandri es una especie conspicua del Pacífico Tropical Oriental. La diagnosis esta basada en especimenes adultos y no existen variaciones documentadas. La inclusión de microestructuras internas a las descripciones permitirá hacer comparaciones intraespecíficas e interespecíficas en taxones con problemas taxonómicos. Objetivo: Describir la morfología externa y las microestructuras internas de O. alexandri, incluida la variación. Métodos: Revisamos el material tipo de O. alexandri y el material en general depositado en tres colecciones científicas. Examinamos las microestructuras internas del brazo y la mandíbula con un microscopio electrónico de barrido. Resultados: Se describió detalladamente la morfología externa e interna mostrando las variaciones morfológicas de acuerdo al tamaño. Conclusiones: Las variaciones de la morfología interna de O. alexandri muestran que es necesario este tipo de análisis, y más importante aún que la morfología externa. Se recomienda realizar mas trabajos taxonómicos que incluyan a otras especies del género para esclarecer su estado taxonómico.

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Section: Discussionunclassified

Morfología y microestructura interna de la estrella quebradiza Ophiocomella alexandri (Echinodermata: Ophiocomidae)

2021

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“…how an animal can interact visually with its environment and the roles vision may have in different species [16,17]. Direct measurements of the image formed by the eye's optics has been a popular approach [18][19][20] in addition to behavioural measurements [10,12,13,[21][22][23][24][25] and the traditional approach with intracellular recordings of angular sensitivity in individual photoreceptors [6]. A problem with behavioural approaches is that they target specific behaviours and not the general visual abilities of the animal.…”

Section: Discussionmentioning

confidence: 99%

Modelling the visual world of a velvet worm

Ljungholm

Nilsson

2021

Preprint

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In many animal phyla, eyes are small and provide only low-resolution vision for general orientation in the environment. Because these primitive eyes rarely have a defined image plane, traditional visual-optics principles cannot be applied. To assess the functional capacity of such eyes we have developed modelling principles based on ray tracing in 3D reconstructions of eye morphology, were refraction on the way to the photoreceptors and absorption in the photopigment are calculated incrementally for ray bundles from all angles withing the visual field. From the ray tracing, we calculate the complete angular acceptance function of each photoreceptor in the eye, revealing the visual acuity for all parts of the visual field. We then use this information to generate visual filters that can be applied to high resolution images or videos to convert them to accurate representations of the spatial information seen by the animal. The method is here applied to the 0.1 mm eyes of the velvet worm Euperipatoides rowelli (Onychophora).These eyes of these terrestrial invertebrates consist of a curved cornea covering an irregular but optically homogeneous lens directly joining a retina packed with photoreceptive rhabdomeres. 3D reconstruction from histological sections revealed an asymmetric eye, where the retina is deeper in the forward-pointing direction. The calculated visual acuity also reveals performance differences across the visual field, with a maximum acuity of about 0.11 cycles/deg in the forward direction despite laterally pointing eyes. The results agree with previous behavioural measurements of visual acuity, and suggest that velvet worm vision is adequate for orientation and positioning within the habitat.

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“…For instance, r-opsin homologs demarcate putative photoreceptor cells at the tube feet of sea urchins [5,6], and in Joseph cells and photoreceptors of the dorsal ocelli of the basal chordate amphioxus [7]. In the case of the brittle star, such non-cephalic photoreceptor cells have been implicated in a form of vision [8]. This implies the evolutionary question to which extent non-cephalic r-opsinpositive cells share an evolutionary history with cephalic eye photoreceptors, or represent independent evolutionary inventions.…”

Section: Introductionmentioning

confidence: 99%

Characterization of cephalic and non-cephalic sensory cell types provides insight into joint photo- and mechanoreceptor evolution

Revilla-i-Domingo

Rajan

Waldherr

et al. 2021

Preprint

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Rhabdomeric Opsins (r-Opsins) are light-sensors in cephalic eye photoreceptors, but also function in additional sensory organs. This has prompted questions on the evolutionary relationship of these cell types, and if ancient r-Opsins cells were non-photosensory. Our profiling of cephalic and non-cephalic r-opsin1-expressing cells of the marine bristleworm Platynereis dumerilii reveals shared and distinct features. Non-cephalic cells possess a full set of phototransduction components, but also a mechanosensory signature. We determine that Pdu-r-Opsin1 is a Gαq-coupled blue-light receptor. Profiling of cells from r-opsin1 mutants versus wild-types, and a comparison under different light conditions reveals that in the non-cephalic cells, light – mediated by r-Opsin1 – adjusts the expression level of a calcium transporter relevant for auditory mechanosensation in vertebrates. We establish a deep learning-based quantitative behavioral analysis for animal trunk movements, and identify a light-and r-Opsin-1-dependent fine-tuning of the worm’s undulatory movements in headless trunks, which are known to require mechanosensory feedback.Our results suggest an evolutionary concept in which r-Opsins act as ancient, light-dependent modulators of mechanosensation, and suggest that light-independent mechanosensory roles of r-Opsins likely evolved secondarily.

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

Cited by 28 publications

References 55 publications

Morfología y microestructura interna de la estrella quebradiza Ophiocomella alexandri (Echinodermata: Ophiocomidae)

Morfología y microestructura interna de la estrella quebradiza Ophiocomella alexandri (Echinodermata: Ophiocomidae)

Modelling the visual world of a velvet worm

Characterization of cephalic and non-cephalic sensory cell types provides insight into joint photo- and mechanoreceptor evolution

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