Royal BC Museum Heidi Gartner

Key to BC Background, glossary, list

BACKGROUND

The sessile, benthic organisms in the phylum Brachiopoda are often referred to as „living ‟ and are commonly known as „lamp shells‟. During the Palaeozoic brachiopods were extremely abundant and were represented by over 12,000 species. Since then brachiopods have decreased in abundance and diversity and are presently represented by less than 400 species. Brachiopods are exclusively marine organisms and can be found from nearly all ocean depths worldwide.

Brachiopods are that superficially resemble mollusc bivalves as their bodies are encased by two calcareous shell valves. However, internally brachiopods differ greatly from mollusc bivalves. The major feature of the body is a large, ciliated, feeding structure called the lophophore. The lophophore is essentially a ring of ciliated tentacles surrounding a mouth that is supported by internal shell structures.

Brachiopods also differ from mollusc bivalves in that they typically attach to the substrate by a fleshy stalk called the pedicle (Figure 1). The pedicle is an extension of the body wall and passes through a hole, called the foramen, in the ventral valve. The ventral valve is therefore referred to as the pedicle valve. Many brachiopods rotate on the pedicle, to utilise ocean currents for feeding, and end up being orientated „upside-down‟. The ventral, or pedicel valve, is therefore the uppermost valve. The dorsal valve, which is usually the lower of the two valves, primarily houses the lophophore and is called the brachial valve. The two valves are unequal and the posterior region of the pedicle valve is referred to as the beak.

There are two major classes of brachiopods, the Articulata and the Inarticulata, that are classified based on the attachment of the two shell valves. In the Inarticulata the two valves are not hinged and are held together entirely by muscles. In the Articulata the valves are hinged by interlocking teeth and sockets. At lower taxonomic levels, brachiopods are further classified by a combination of external shell features and internal anatomy, primarily relating to the support of the lophophore.

NOTES ABOUT THIS KEY This key was designed to be easy-to-use and accessible to a diverse audience. As such, I have focused on describing gross morphology and external features as much as possible. Biologists searching for more detailed information on internal anatomy should consult the references listed at the bottom of each species description page. This key was largely based on the following publication of F.R. Bernard: Bernard, F. R. 1872. “The living Brachiopoda of British Columbia.” Syesis 5:73-82.

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Royal BC Museum Heidi Gartner

Figure 1. Schematics of the generalised external anatomy of a brachiopod a) lateral view and b) dorsal view. In the lateral view, note the relative position of the ventral and dorsal valves due to the rotation of the pedicle. (Adapted from Clarkson, 1986)

GLOSSARY OF TERMS Beak – The posterior pointed region of the pedicle valve. In most brachiopods this is where the foramen is located.

Brachial valve – The dorsal shell valve which primarily houses the lophophore and any support structures. This is usually the smaller of the two valves.

Foramen – The hole in the pedicle shell valve through which the pedicle passes.

Lophophore – The large, ciliated, internal feeding organ that is composed of a pair of tentacle- bearing arms that extend anteriorly into the mantel cavity.

Pedicle – The fleshy stalk that is used to attach to, or burrow into, the substrate. The pedicle is an extension of the body wall.

Pedicle valve – The ventral shell valve through which the pedicle passes. This is usually the larger of the two valves.

Punctae – Perforations in the shell valves.

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Sulcate – Having furrows and folds (and corresponding depressions called sulcus) along the anterior margin of the shell valves.

SPECIES LIST To date, eleven species of brachiopods have been reported from British Columbia. However, if you find a brachiopod that does not fit with the description of any of these species, do not despair; new species are always being discovered and described, species ranges are shifting in response to climate change, and species are being transported and introduced to new regions by human activities. Keep exploring and researching.

CLASS INARTICULATA FAMILY CRANIIDAE californica Berry, 1921

FAMILY DISCINIDAE Discinisca lamellosa (Broderip, 1834)

CLASS ARTICULATA FAMILY CANCELLOTHYRIDIDAE Terebratulina unguicula (Carpenter, 1864) Terebratulina crossei Davidson 1882 Terebratulina kiiensis Dall & Pilsbry 1891 Terebratulina sp. indet– There are brachiopods that have intermediate characteristics of the species Terebratulina crossei and Terebratulina kiiensis. There has also been much discussion about whether these two species are actually conspecifics (e.g. Foster, 1989). These intermediate brachiopods either represent part of the continuum of characteristics of the species T. kiiensis (with T. crossei synominised), or are in fact new a species within the Terebratuilna .

FAMILY FRIELEIIDAE Frieleia halli Dall, 1895

FAMILY HEMITHYRIDIDAE Hemithiris psittacea (Gmelin, 1790)

FAMILY LAQUEIDAE Laqueus californianus (Koch, 1848)

FAMILY PLATIDIIDAE Platidia hornii (Gabb, 1861)

FAMILY TEREBRATALIIDAE Diestothyris frontalis (Middendorff, 1849) Terebratalia transversa (Sowerby, 1864)

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REFERENCES FOR BACKGROUND AND GLOSSARY

Brusca, Richard C. and Gary J. Brusca. 2003. Invertebrates (2nd edition). Sunderland: Sinauer Associates, Inc.

Carlton, James T., editor. 2007. The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon (4th edition). Berkeley: University of California Press.

Clarkson, E. N. K. 1986. Invertebrate Paleontology and . London: Allen & Unwin Ltd.

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