Demospongia (Order: Monaxonida)
Wapkia is considered a primitive demosponge (Rigby, 1986). Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.
Wapkia – origin of name is unknown
grandis – from the Latin grandis, “large.” This name refers to the large size and complex skeleton of this sponge.
Lectotype –USNM66458 (W. grandis), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Holotype –ROM53544 (W. elongata), in the Royal Ontario Museum, Toronto, Canada.
Burgess Shale and vicinity: W. elongata Rigby and Collins, 2004 from the Tulip Beds (S7) on Mount Stephen.
Other deposits: none.
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
The Walcott Quarry on Fossil Ridge. The Tulip Beds (S7) on Mount Stephen.
Brief history of research:
Wapkia was described by Walcott in his initial description of the Burgess Shale sponges in 1920. The genus was re-examined by Rigby in 1986. Rigby and Collins (2004) also redescribed the genus and proposed a new species, W. elongata.
Wapkia is a large elongate or oval sponge with bundles of coarse and fine spicules aligned in long vertical columns and distinct horizontal bundles. The surface of the sponge is smooth and lacks any vertical or horizontal ridges. Spicules are straight and pointed at both ends (oxeas). The exact position of the various bundles of spicules in the skeleton is still uncertain, but it seems that the inner part of the skeleton is reticulate with horizontal wrinkles that are typical of the species and produced by horizontal bundles of spicules. The dermal layer is formed by bundles of oxeas up to 60 mm long which give a characteristic plumose aspect to this sponge. W. elongata is distinguished from W. grandis based on the overall shape of the sponge and different skeletal structures (varying distance between the horizontal spicule bundles).
Wapkia is rare and represents only 0.06% of the Walcott Quarry community (Caron and Jackson, 2008).
Wapkia 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.