Overview
Introduction
Economic Importance
Physical Description
Size
Ecology
Local Occurrence
Global Distribution
Crypsis
Life History & Behaviour
Life Cycle & Reproduction
Locomotion
Feeding (Report)
Anatomy & Physiology
Nervous System
Musculature
Respiration, Circulation & Excretion
Evolution & Systematics
Systematics
Conservation & Threats
Conservation
Threats
References |
LOCOMOTION
Medusae jet-swim by the rapid contraction of their bells (Ruppert et al., 2004), and display a wide range of swimming behaviours (Colin & Costello, 1996). Hydromedusae live and swim in water, so variations in swimming behaviour result in different hydrodynamic forces influencing motion (Colin & Costello, 1996). The principal muscle used in medusa swimming is the circular coronal muscle (Ruppert et al., 2004). The contraction of the coronal muscle results in periodic contractions of of the bell. Thrust is generated by fluid being forced through the velar aperture and away from the body (Colin & Costello, 1996), ultimately pushing the jellyfish forwards. This is demonstrated in Figure 4.3.
Figure 4.4: Generalised swimming action of hydromedusae.
Adapted from Ruppert et al., 2004. |
Swimming is strongly correlated with the capture of prey. Jellyfish are opportunistic predators, relying on swimming to bring them into contact with their intended prey. An example of this is Aequorea victorias where foraging strategies have been observed to be consistent with continuous swimming (Colin & Costello, 1996).
The swimming activity of Aequorea sp. was observed in both natural and tank environments. In situ, Aequorea sp. was found to swim, but relied primarily on currents for transportation. In the tank environment, Aequorea sp. was observed to swim rather passively. Below is a video taken of Aequorea sp. swimming in the holding tank.
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