Other Gastropods that Carry Shells

My previous post concerned the "carrier" gastropod Xenophora, the most common example of a marine gastropod that cements foreign objects onto/into its shell.


In this new post, I present a very broad overview of the other main examples of "carrier" gastropods." 

A high-spired Straparollus, approximately 1 cm height, with fragments of shells attached to its whorls.

One of these other "carrier" gastropods is Straparollus, of Ordovician to Devonian age in North America. Whether this gastropod crawled or was stationary (sessile) is unknown. Straparollus has an uncertain classification and evolution. I used the following reference for obtaining information about Straparollus and as the basis for my own sketch of its shell:

Linsley, R.M. and E.L. Yochelson. 1973. Devonian carrier shells (Euomphalidae) from North America and Germany. United States Geological Survey Professional Paper 824, pp. 1–26.
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Scaliola bella, 1.2 mm height, Indonesia.

Another "carrier gastropod," is the minute Scaliola, which ranges from the Cretaceous to modern day. There are only a few species, and specimens are generally less than 1 mm in height. They live predominantly in the Indonesia region of the Indo-Pacific ocean region. This gastropod cements sand grains onto the adult part of its shell. The family placement of Scaliola is quite different from that of Xenophora.

The following reference was used for obtaining information about Scaliola and as the basis for my own sketch of its shell.

Bandel, K. and H. A. El-Nakhal. 1993. The history and relationship of Scaliola, a gastropod that cements particles to its shell. Mittelungen aus dem Geologisch Palaontologische Institut der Universität Hamburg, 73:171–191.

The following two groups of "carriers" are not true "carriers" of shells upon their own shell, buy they do collect foreign objects and glue them onto themselves. Thus, they are of interest, in a comparative way. The first group is the microscopic agglutinated foraminifers, which are amoeba-like, one-cell protists. Their geologic record ranges from the Early Paleozoic (Middle Ordovician).

Agglutinated (also referred to as arenaceous) foraminifers cement sand, mica, or calcareous particles, as well as tests of other micro-organisms (especially sponge spicules), onto themselves. The cement is calcium carbonate, silica, or iron-bearing compounds. The type of material they attach to can be dependent upon the temperature of the surrounding ocean water (e.g., quartz grains in cold water versus calcium-carbonate particles in warm water). Two examples are: 

Sand-grain agglutinated foraminifer Rhadbdammina, 0.1 mm height, Ordovician, Oklahoma. 

Sand-grain aggluinated foraminifer Saccammina, 0.05 mm height, Silurian, Oklahoma.
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The second group of debatable carriers are some amphipods, which are microscopic shrimp-like crustaceans having no carapace (hard "shell-like covering). This type of amphipod "collects" pieces of shells, cuts them, and then cements them onto its sides (thereby forming blisters or tubes). I could not fine any images of them, and I do not believe that they have a known fossil record.