The shell structure and chamber production cycle of the cephalopod Spirula (Coleoidea, Decabrachia)

The endocochleate coleoid cephalopod Spirula spirula , the only present-day representative of the order Spirulida, secretes a coiled shell consisting of a series of chambers divided by septa and connected by a siphuncle. It is the shell closest to those of Recent and extinct ectochleate cephalopods:...

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