Francois Hugo submitted this exquisite photograph of a paper nautilus (Argonauto argo) that he found washed up on the beach at Struisbaai on Friday afternoon 22 August 2014.
The paper nautilus belongs to the molluscan class Cephalopods which includes octopi, squid and cuttlefish – “the most advanced molluscs and among the most sophisticated and largest of the invertebrates.” (Two Oceans, a guide…). The foot and head of the creatures are merged with the former divided into 8-10 arms. Their mouths are parrot-like beaks.
The female paper nautilus grows up to 100mm in size whereas the male is tiny and lacks a shell. The shell of the female serves mainly as a brood chamber for her eggs. The females float near the surface of the sea – the air trapped inside the shell keeping them buoyant -and are sometimes washed ashore by stormy seas. Not only are they much larger than the males, they also reproduce many times and live much longer. The male nautilus reproduces only once. When mating one of his arms breaks off inside the mantle of the female, transferring his sperm to her. Early scientists centuries ago thought that this male reproductive arm was a parasitic worm which they called a Hectocotylus. The name has been retained.
Paper nautili are found in tropical and subtropical waters. Their prey includes salps and jellyfish which they inject with poison from their salivary glands
Sources of info:
Two Oceans: A guide to the marine life of southern Africa by GM Branch et al