Ethological implications from a detailed X-ray radiograph and 14C study of the modern deep-sea Zoophycos
The modern Zoophycos found in deep-sea sediments from the Portuguese continental margin differs markedly from most Zoophycos described from the fossil record. A detailed X-ray radiograph analysis revealed that the trace consists of an upwards constructed, helically coiled spreite that is connected to the sediment surface through a single shaft. Comparison of 14C dates from spreiten material and directly surrounding sediment revealed age differences of up to more than 2500 years, the spreiten material always being younger. This clearly shows that the spreiten material was collected on the seafloor and transported into the sediment. Together with raised levels of organic carbon in the spreiten compared to the surrounding sediment, this indicates a selective detritus feeding behavior of the tracemaker. Detailed studies of the bathymetrical and regional distribution of Zoophycos in archived X-ray radiographs stored at Kiel University, Germany, reveal that the trace is strictly confined to deep, calm settings where most organic carbon reaches the seafloor in pulses. On the basis of these findings the traditional interpretation of Zoophycos as a deposit feeder is rejected in favor of a combined detritus feeder and cache model for the modern deep-sea Zoophycos.