The hydrothermal volcanic vents along deep ocean floors host ephemeral ecosystems of diverse endemic fauna, but given the absence of light at such depths the role of vision in this environment has been underinvestigated. In November 7 Nature, Robert Jinks and colleagues at the Franklin and Marshall College, Lancaster, Pennsylvania, USA, show that adult Pacific vent crab (Bythograea thermydron) possess high-sensitivity naked-retina eyes adapted to detect dim, longer wavelength light (Nature, 420:68-70, November 7, 2002).

Jinks et al. examined the visual metamorphoses that accompany the larva to adult transition in B. thermydron. They observed that during development these organisms lose their image-forming optics and develop high-sensitivity naked-retina eyes. In addition, they showed that the spectral absorbance of the visual pigment in these eyes shifts towards longer wavelengths in response to the change from planktonic larva to benthonic adult. They suggest that this ability...