Gut contents as direct indicators for trophic relationships in the Cambrian marine ecosystem

Present-day ecosystems host a huge variety of organisms that interact and transfer mass and energy via a cascade of trophic levels. When and how this complex machinery was established remains largely unknown. Although exceptionally preserved biotas clearly show that Early Cambrian animals had alread...

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Bibliographic Details
Published in:PloS one 2012-12, Vol.7 (12), p.e52200-e52200
Main Author: Vannier, Jean
Format: Article
Language:English
Subjects:
Animals
Aquatic Organisms
Arthropoda
Arthropods
Behavior
Biology
Biota
Brachiopoda
Cambrian
Complexity
Diet
Digestive System
Earth Sciences
Ecology
Ecosystem
Feeding
Feeding behavior
Food Chain
Food resources
Fossils
Geological Phenomena
Histology
Invertebrates
Machinery and equipment
Marine ecosystems
Morphology
Museums
Organic matter
Paleontology
Pharynx
Polychaeta
Predation
Priapulida
Priapulidae
Priapulus caudatus
Sciences of the Universe
Sediments (Geology)
Shale
Sipuncula
Stratigraphy
Trophic levels
Trophic relationships
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Summary:Present-day ecosystems host a huge variety of organisms that interact and transfer mass and energy via a cascade of trophic levels. When and how this complex machinery was established remains largely unknown. Although exceptionally preserved biotas clearly show that Early Cambrian animals had already acquired functionalities that enabled them to exploit a wide range of food resources, there is scant direct evidence concerning their diet and exact trophic relationships. Here I describe the gut contents of Ottoia prolifica, an abundant priapulid worm from the middle Cambrian (Stage 5) Burgess Shale biota. I identify the undigested exoskeletal remains of a wide range of small invertebrates that lived at or near the water sediment interface such as hyolithids, brachiopods, different types of arthropods, polychaetes and wiwaxiids. This set of direct fossil evidence allows the first detailed reconstruction of the diet of a 505-million-year-old animal. Ottoia was a dietary generalist and had no strict feeding regime. It fed on both living individuals and decaying organic matter present in its habitat. The feeding behavior of Ottoia was remarkably simple, reduced to the transit of food through an eversible pharynx and a tubular gut with limited physical breakdown and no storage. The recognition of generalist feeding strategies, exemplified by Ottoia, reveals key-aspects of modern-style trophic complexity in the immediate aftermath of the Cambrian explosion. It also shows that the middle Cambrian ecosystem was already too complex to be understood in terms of simple linear dynamics and unique pathways.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0052200