title: A novel eye in 'eyeless' shrimp from hydrothermal vents of the Mid-Atlantic Ridge.
abstract: Rimicaris exoculata is a shrimp that swarms over high-temperature (350 degrees C) sulphide chimneys at Mid-Atlantic Ridge hydrothermal fields (3,600 m). This shrimp lacks an externally differentiated eye, having instead a pair of large organs within the cephalothorax immediately beneath the dorsal surface of the transparent carapace, connected by large nerve tracts to the supraesophageal ganglion. These organs contain a visual pigment with an absorption spectrum characteristic of rhodopsin. Ultrastructural evidence for degraded rhabdomeral material suggests the presence of photoreceptors. No image-forming optics are associated with the organs. We interpret these organs as being eyes adapted for detection of low-level illumination and suggest that they evolved in response to a source of radiation associated with the environment of hydrothermal vents.
authors.affiliation: Woods Hole Oceanographic Institution, Massachusetts 02543.
authors.forename: C L
authors.initials: CL
authors.lastname: Van Dover
authors.forename: E Z
authors.initials: EZ
authors.lastname: Szuts
authors.forename: S C
authors.initials: SC
authors.lastname: Chamberlain
authors.forename: J R
authors.initials: JR
authors.lastname: Cann
mesh_terms: D000818:Animals; D033364:Decapoda / Q000033:anatomy & histology*; D005123:Eye / Q000032:analysis / Q000033:anatomy & histology*; D006358:Hot Temperature; D010786:Photoreceptor Cells / Q000032:analysis / Q000033:anatomy & histology; D012168:Retinal Pigments / Q000032:analysis; D012243:Rhodopsin / Q000032:analysis; D013053:Spectrophotometry
chemical_list: D012168:Retinal Pigments; D012243:Rhodopsin