Scaphopoda

Dentalium eburneum; collecting on Cigenter Beach – Java

Scaphopods or tuskshells are shell-bearing organisms. Their common name points to the shape of their shells that resembles an elephants tusk. The scaphopod’s shell is a conical tube, curved and open at both ends. The anterior aperture (opening), usually the point of largest diameter of the shell, allows extension of the foot and captacula. The smaller posterior aperture is an exit for gametes and faeces. Only in Cadulus the broadest diameter of the shell is reached near the middle of the tube. The range in size of tuskshells goes from a few millimetres to several centimetres. Scaphopods are exclusive marine creatures; they are infaunal burrowers and feed on foraminifera’s and detritus. They catch their prey with small tentacles, called captacula. No other life form on Earth as this kind of appendages. The captacula look like the tentacles of a cephalopod, for this reason the tuskshells were long time seen as closely related to octopuses and squid. Scaphopods have a worldwide distribution. They are found in sand and mud from intertidal flats to abyssal depths. Though widely distributed, they are seldom found in large numbers.

Scaphopoda form a class in the phylum of the Mollusca. More common classes of molluscs are bivalves, like the blue mussel (Mytilus edulis Linnaeus 1758) and gastropods, like the whelk (Buccinum undatum Linnaeus, 1758). The tuskshells appear around 360 Mya (million years ago) in the fossil record and are believed to be evolutionary related to bivalves. At the moment about 800 fossil and ca. 500 recent species are known to science.

Fissidentalium capillosum

I find scaphopods amazing because they are around for about 360 million years without noticeable changes. They survived at least four mass extinctions. And… They fossilize well, so they can be collected in many fossil sites. They flourished along the shores of Gondwanaland and do still along its scattered fragments. So they are survivors pur-sang, and that is what I like about them.

For over thirty years I followed their traces around the globe, and I suppose I will continue doing so for as long as I’m able.

In spring 2013 Bernd Sahlmann, Jordy van der Beek and I decided to focus on the scaphopod-fauna of the Red Sea. In April we had a workshop in the Haus der Natur in Cismar (Germany) to discuss the material from this region in our collections. Henk Dekker from the Dutch Malacological Society kindly gave us access to his extensive collection of Red Sea scaphopods.

Gadila cf clavata (Gould, 1859) from the Red Sea. Photo by Joop Trausel NMR

Gadila cf clavata (Gould, 1859) from the Red Sea. Photo by Joop Trausel NMR

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