In the field of zoology, a spadix ( ; plural spadices , ) is a secondary sexual organ found in some

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s and

hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specializ ...

ns. In the genus ''

Nautilus The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in t ...

'', the spadix is a composite

erectile Erectile tissue is tissue in the body with numerous vascular spaces, or cavernous tissue, that may become engorged with blood. However, tissue that is devoid of or otherwise lacking erectile tissue (such as the labia minora, the vestibule/vagina an ...

organ in the male located in the oral region which is composed of four highly modified tentacles and which is paired with a somewhat smaller antispadix that is also composed of four

tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

. The spadix is normally a concealed organ but quickly becomes distended upon the animal's death. The exact function of the spadix and antispadix in ''Nautilus'' is not yet known.

References

Cephalopod zootomy Sex organs {{Animal-anatomy-stub

See also

References