Cambrian cinctan echinoderms shed light on feeding in the ancestral deuterostome

Imran A Rahman, Samuel Zamora, Peter L. Falkingham, Jeremy C Phillips

Research output: Contribution to journalArticle (Academic Journal)peer-review

11 Citations (Scopus)
255 Downloads (Pure)

Abstract

Reconstructing the feeding mode of the latest common ancestor of deuterostomes is key to elucidating the early evolution of feeding in chordates and allied phyla; however, it is debated whether the ancestral deuterostome was a tentaculate feeder or a pharyngeal filter feeder. To address this, we evaluated the hydrodynamics of feeding in a group of fossil stem-group echinoderms (cinctans) using computational fluid dynamics. We simulated water flow past three-dimensional digital models of a Cambrian fossil cinctan in a range of possible life positions, adopting both passive tentacular feeding and active pharyngeal filter feeding. The results demonstrate that an orientation with the mouth facing downstream of the current was optimal for drag and lift reduction. Moreover, they show that there was almost no flow to the mouth and associated marginal groove under simulations of passive feeding, whereas considerable flow towards the animal was observed for active feeding, which would have enhanced the transport of suspended particles to the mouth. This strongly suggests that cinctans were active pharyngeal filter feeders, like modern enteropneust hemichordates and urochordates, indicating that the ancestral deuterostome employed a similar feeding strategy.
Original languageEnglish
Article number20151964
Number of pages7
JournalProceedings of the Royal Society B: Biological Sciences
Volume282
Issue number1818
Early online date28 Oct 2015
DOIs
Publication statusPublished - 7 Nov 2015

Keywords

  • echinoderms
  • deuterostomes
  • evolution
  • feeding
  • functional morphology
  • computational fluid dynamics

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