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Louisella pedunculata

A large spiny, carnivorous worm

Reconstruction of Louisella pedunculata.

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Reconstruction of Louisella pedunculata.

© Marianne Collins

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Unranked clade (stem group priapulids)


Louisella has been compared to the nemathelminth worms (Maas et al., 2007), but most analyses support a relationship with the priapulids at a stem-group level (Harvey et al., 2010; Wills, 1998).

Species name:

Louisella pedunculata

Described by:


Description date:



Louisella – from Lake Louise, a lake near the Burgess Shale that was named after Princess Louise Caroline Alberta (1848-1939), the wife of the Governor General of Canada Marquis of Lorne and Queen Victoria’s fourth daughter.

pedunculata – from the Latin diminutive pedunculus, “foot,” in reference to small foot-like structures (papillae) along the body.

Type Specimens:

Holotype –USNM57558 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.

Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

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Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).

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Principal localities:

The Walcott Quarry on Fossil Ridge.

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History of Research

Brief history of research:

When he first described it in 1911,Walcott originally considered his single specimen of Louisella to be a sea-cucumber, recognizing a flattened “sole” and tentacles at either end (Walcott, 1911a); unusual folding of the Louisella holotype had given its rows of papillae (“pimples”) the appearance of tentacles at the front and back. He subsequently described additional material as a new annelid worm, Miskoia preciosa (Walcott, 1911b), but this was eventually synonymised with Louisella by Conway Morris (1977) who recognized it as a primitive priapulid worm.

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Louisella is the largest priapulid in the Burgess Shale, reaching 30 cm in length. Like all priapulids, the organism is an annulated worm with an invertable, tooth-lined feeding structure (proboscis) at the front end of the body; it had a straight gut leading directly from the mouth at the front to the anus at the rear. The trunk of the worm displayed four discrete sections, distinguished by their surface texture. Rings of short spines encircled the body of the worm, and two rows of pimples (papillae – possibly used as gills) extended along one surface of the worm. The rear-most portion of the organism did not possess spines, and could be inverted into the tail end of the animal. The proboscis itself was covered with an array of spines, with a ring of twenty-five longer spikes near its midlength. It could be turned inside-out (everted) and extruded from the organism.


This species is only known in the Walcott Quarry where it is relatively rare, representing 0.09% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum size:

300 mm

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Life habits:

Endobenthic, mobile

Feeding strategies:


Ecological Interpretations:

Louisella was a burrowing worm, possibly spending some time on the surface. It was carnivorous, and its proboscis seems to be suited to grinding food, suggesting that it fed on larger prey items. However, it is not clear whether Louisella was an active hunter, or scavenged on dead carcasses. Possible sediment in the gut suggests that it may have fed on organisms within the sediment, or ingested mud as it fed – although the mud may have entered after death.

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CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CONWAY MORRIS, S. 1977. Fossil priapulid worms. Special Papers in Palaeontology, 20: 1-95.

CONWAY MORRIS, S. AND J. S. PEEL. 2009. New Palaeoscolecidan Worms from the Lower Cambrian: Sirius Passet, Latham Shale and Kinzers Shale. Acta Palaeontologica Polonica, 55(1): 141-156.

HARVEY, T. H. P., X. DONG AND P. C. J. DONOGHUE. 2010. Are palaeoscolecids ancestral ecdysozoans? Evolution & Development, 12(2): 177-200.

MAAS, A., D. HUANG, J. CHEN, D. WALOSZEK AND A. BRAUN. 2007. Maotianshan-Shale nemathelminths - Morphology, biology, and the phylogeny of Nemathelminthes. Palaeogeography, Palaeoclimatology, Palaeoecology, 254(1-2): 288-306.

WALCOTT, C. 1911a. Cambrian Geology and Paleontology II. Middle Cambrian holothurians and medusae. Smithsonian Miscellaneous Collections, 57(3): 41-68.

WALCOTT, C. 1911b. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.

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