The nuchal organ is a ciliated pit[1] or groove present at the posterior end of the prostomiumofannelid worms,[1] some cephalopods,[2] and other invertebrates.[3]
Annelids only possess one nuchal organ, although the nature of the grooving may make it appear to be a pair of organs.[4]
It may be involved in light detection,[2] and may have a role in food detection and mating.[5]
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Cephalopod anatomy
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| Shell |
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| Mantle & funnel |
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| Head & limbs |
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| General |
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Developmental stages: Spawn → Paralarva (Doratopsis stage) → Juvenile → Subadult → Adult • Egg fossils • Protoconch (embryonic shell) | ||||||||||||||
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