The Burgess Shale

Pirania muricata

A cactus-like sponge

3D animation of Pirania muricata and other sponges (Choia ridleyi, Diagoniella cyathiformis, Eiffelia globosa, Hazelia conferta, Vauxia bellula, and Wapkia elongata) and Chancelloria eros a sponge-like form covered of star-shaped spines.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Animalia
Phylum: Porifera
Class: Demospongea (Order: Monaxonida)
Remarks:

Pirania is considered a primitive demosponge (Rigby, 1986). Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.

Species name: Pirania muricata
Described by: Walcott
Description date: 1920
Etymology:

Pirania – from Mount Saint Piran (2,649 m), situated in the Bow River Valley in Banff National Park, Alberta. Samuel Allen named Mount St. Piran after the Patron Saint of Cornwall in 1894.

muricata – from the Latin muricatus, “pointed, or full of sharp points.” The name refers to the large pointed spicules extending out from the wall of the sponge.

Type Specimens: Lectotype –USNM66495 (erroneously referred as 66496 in Rigby, 1986), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none

Other deposits: Pirania auraeum Botting, 2007 from the Lower Ordovician of Morocco (Botting, 2007); Pirania llanfawrensis Botting, 2004 from the Upper Ordovician of England (Botting, 2004).

Age & Localities:

Period:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott Quarry on Fossil Ridge. The Trilobite Beds and Tulip Beds (S7) on Mount Stephen and several smaller sites on Mount Field, Mount Stephen and Mount Odaray.

History of Research:

Brief history of research:

Pirania was first described by Walcott (1920). Rigby (1986) redescribed this sponge and concluded that the skeleton is composed of hexagonally arranged canals, large pointed spicules and tufts of small spicules. This sponge was also reviewed by Rigby and Collins based on new material collected by the Royal Ontario Museum (2004).

Description:

Morphology:

Pirania is a thick-walled cylindrical sponge that can have up to four branches. The skeleton of the sponge is composed of tufts of small spicules and has very distinctive long pointed spicules that emerge from the external wall. Long canals perforate the wall of the sponge to allow water flow through it. Branching occurs close to the base of the sponge.

Abundance:

Pirania is common in most Burgess Shale sites but comprises only 0.38% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
30 mm

Ecology:

Life habits: Epibenthic, Sessile
Feeding strategies: Suspension feeder
Ecological Interpretations:

Pirania would have lived attached to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall. The brachiopods Nisusia and Micromitra a range of other sponges and even juvenile chancelloriids are often found attached to the long spicules of this sponge, possibly to avoid higher turbidity levels near the seafloor.

References:

BOTTING, J. P. 2004. An exceptional Caradoc sponge fauna from the Llanfawr Quarries, Central Wales and phylogenetic implications. Journal of Systematic Paleontology, 2: 31-63.

BOTTING, J. P. 2007. ‘Cambrian’ demosponges in the Ordovician of Morocco: insights into the early evolutionary history of sponges. Geobios, 40: 737-748.

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

RIGBY, J. K. 1986. Sponges of the Burgess shale (Middle Cambrian), British Columbia. Palaeontographica canadiana, 2: 105 p.

RIGBY, J. K. AND D. COLLINS. 2004. Sponges of the Middle Cambrian Burgess Shale and Stephen Formations, British Columbia. Royal Ontario Museum Contributions in Science (1): 155 p.

WALCOTT, C. D. 1920. Middle Cambrian Spongiae. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67(6): 261-365.

Other Links:

None