Time series analysis and model of heart-beat rate, oxygen consumption, and locomotor activity from the sand-crab Portunus pelagicus (linnaeus)
Auto-correlation, cross-correlation, and Fourier transform decomposition were applied to data on parameters of perfusion, respiration, and behaviour in P. pelagicus. Cardiac activity, although discontinuous in buried crabs, formed a regular alternating time-series with a stable periodicity. Cross- correlation showed a close temporal linking between cardiac activity and oxygen consumption over 24 hours. Similar temporal patterns were observed in locomotor activity. Pausing (bradycardia) and pulsing (tachycardia) were investigated by 'power spectrum' analysis and summarised in the form of a Fourier transform model.