We studied the juvenile jellyfish, called ephyra (Fig. 1B). They are typically 3–5 mm in diameter, with eight arms evenly spaced around a disc-shaped body. The symmetrical contraction of the arms is critical for generating fluid vortexes that facilitate propul- sion and filter feeding (Sullivan et al., 1997; Higgins et al., 2008). As ephyrae grow into medusae, bell tissue forms between each arm, which takes weeks to months, depending on nutrition abundance.