| http://www.w3.org/ns/prov#value | - They have limited control over movement, but can use their hydrostatic skeleton to navigate through contraction-pulsations of the bell-like body; some species actively swim most of the time, while others are mostly passive.][ The body is composed of over 95% water; most of the umbrella mass is a gelatinous material ??? the jelly ??? called mesoglea which is surrounded by two layers of protective s
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