The Residents Association of Dana Bay Conservancy We care about our environment

Argonaut nodosa	Deadly debris	Shrimp & Krill

The Paper Nautilus is a type of octopus found in temperate and tropical waters world wide. This species is called Argonauts nodosa (nodosa refers to the knobs or nodules on the shell). Only the female has a shell which serves as a brood chamber and a flotation device. This shell is secreted by the greatly extended web of one pair of arms. Young females kept in aquaria have been found to start building a shell twelve days after hatching. It is a general thought that they carry their shells throughout their lives, adding to the outer edge as they grow. However there is strikingly little biological information known about them.

The young, look like miniature adults when they hatch, have been collected down to a depth of 500 metres (mostly in the upper 100 metres). Young males and mature females are most often caught at the surface where they feed on small planktonic animals during the day.  They have also been observed feeding on molluscs, jellyfish and salps.  (See archive on salps on our website).

Unlike other cephalopods (squids, cuttlefish and other octopus) which die soon after spawning it seems likely that the female Paper Nautilus may live for several years which might explain the variation in the size of the animals washed up.  They are capable of colour change and may squirt ink to confuse predators.

The males are tiny, about 1.5 centimetres long.  (Females may grow to 30cm). They do not have webbed arms like the females but have one very long arm which they carry in a coiled sac. This arm is called the hectocotylus and contains the sperm. During mating this arm breaks off inside the mantle or body of the female.

In Dana Bay, we have been fortunate to pick up these animals over the past 2 weeks.  They were last stranded during September 2006.  Apparently the sea gulls find them and bring them to shore where they eat the octopus and/or the eggs.  Most of the Nautilus shells on the beach show signs of pecking.

Floating debris, like plastic, unfortunately is easily mistaken by sea animals as edible pieces of nautilus, squid, jellyfish, bluebottles or shrimp. Sea turtles are highly susceptible to ingesting plastic as they feed on bluebottles and jellyfish. A stranded dead Humpback Whale was dissected and found to contain 27kg of plastic in its digestive system!

Human garbage not disposed of hygienically pollutes our vast and spectacular coastline on a regular basis.  Please remember to help during the International Beach Clean-up week of 18-25 September 2010.  Contact the Conservancy at info@danabayactive.co.za if you are interested in helping.  Also see the notice board at Friendly Grocer and watch for articles in the Mossel Bay Advertiser.