Related topics: brain · nerve cells · current biology · retina

Explaining a supernova's 'string of pearls'

Physicists often turn to the Rayleigh-Taylor instability to explain why fluid structures form in plasmas, but that may not be the full story when it comes to the ring of hydrogen clumps around supernova 1987A, research from ...

Unraveling the mystery of chiton visual systems

You'd probably walk past a chiton without even seeing it. These creatures often look like nothing more than another speck of seaweed on the crusty intertidal rocks. But it sees you. At least, if it's one of the species with ...

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Eye

Eyes are organs that detect light, and send signals along the optic nerve to the visual and other areas of the brain[citation needed]. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in cnidaria, molluscs, chordates, annelids and arthropods.

The simplest "eyes", such as those in unicellular organisms, do nothing but detect whether the surroundings are light or dark, which is sufficient for the entrainment of circadian rhythms. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment.

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