Kingdom:

Animalia

Phylum:

Ctenophora

Class:

Unranked clade (stem group ctenophores)

Affinity:

Ctenorhabdotus is regarded as a very primitive ctenophore, possibly representing a stem-group member (Conway Morris and Collins, 1996).

Species name:

Ctenorhabdotus capulus

Described by:

Conway Morris and Collins

Description date:

1996

Etymology:

Ctenorhabdotus – from the Greek ktenos, “comb,” and rhabdotos, “striped,” in reference to the pronounced striped-like appearance of the comb-rows.

capulus – from the Latin capulus, “a handle,” in reference to the prominent aboral capsule-like element.

Type Specimens:

Holotype – ROM 50822 in the Royal Ontario Museum, Toronto, Canada.

Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

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Period:

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

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Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge.

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Brief history of research:

Ctenorhabdotus capulus was described by Conway Morris and Collins in 1996 and no additional studies have been published since then.

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Morphology:

Ctenorhabdotus is ovoid in shape and bears 24 comb-rows. The top (aboral) and bottom (oral) surfaces are relatively flat. The comb-rows are organised in 8 sets of three, with the central row being much shorter than the two flanking ones. Each group of three comb rows converges towards the aboral side to form 8 strands. The oral region is well developed with an undulating margin. There is a small capsule-like structure on the aboral side of the animal which is thought to include an apical organ and statocysts.

Abundance:

Ctenorhabdotus is rare, known from about two dozen specimens, mostly from the Raymond Quarry. In the Walcott Quarry, this species comprises only 0.01% of the specimens counted (Caron and Jackson, 2008).

Maximum size:

70 mm

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Life habits:

Nektonic, mobile

Feeding strategies:

Unknown

Ecological Interpretations:

The presence of comb-rows suggests the animal was an active swimmer. Its mode of feeding is more conjectural as the mouth is not well preserved and there is no evidence of tentacles.

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