The animals have weak musculature , but maintain agility and buoyancy with little effort because of sophisticated statocysts ( balancing organs akin to a human 's inner ear ) and ammonium-rich gelatinous tissues closely matching the density of the surrounding seawater .
The animals have weak musculature but maintain agility and buoyancy with little effort thanks to sophisticated statocysts ( balancing organs akin to a human 's inner ear ) and ammonium-rich gelatinous tissues closely matching the density of the surrounding seawater .