The Knysna Estuary and associated wetlands is the most ecologically important estuary in the country. According to several scientific studies relating to birds, fish and plants, it ranks higher than all other estuaries in terms of its natural importance. It hosts 43% of all of South Africa’s estuarine natural life – all the more incredible, because the Knysna estuary is just 1 800 hectares in size.
The sea grass meadows around Leisure Isle, for example, support over 90% of the species occurring in the whole estuarine bay. The sea grass in Knysna also supports a number of high-profile rarities (besides the well-known sea-horse) including various small snails and sea-slugs for which it is the only known place in Africa south of the Sahara where they occur.
It’s then perhaps of little surprise that unfamiliar things still sometimes emerge. This happened recently when a citizen brought Garden Route National Park rangers an unknown creature found in the estuary. After referring to the Marine Guide booklet (two oceans), it was identified as an Argonauta argo.
Commonly referred to as a paper nautilus or Greater Argonaut, it’s a type of pelagic octopus belonging to the genus Argonauta. Pelagic refers to a certain zone of ocean or in this case, a zone in the estuary.
All argonauts create a paper-thin eggcase that coils around the octopus, similar to molluscs in their shells – hence the name of paper nautilus. According to the Marine Guide Booklet, “the Chinese name for this species translates into ‘white sea-horse’s nest.” Males of this species grow up to eight millimeters whilst females mature at about double the size, although they can grow up to 100 mm. Males do not exceed 20 mm. Its paper-thin shells are treasured by beach-goers.