When they hatch, sea angel larvae do have an embryonic shell, but they discard it within a few days. Their lack of shell is referenced in their clade name: Gymnosomata, which means "naked body" in Greek. The largest sea angels grow up to 5 cm (2 in) long, and most species survive entirely on sea butterflies, another type of smaller gastropod. One kind of sea angel, Clione antarctica, produces the molecule pteroenone as a defense mechanism. It's effective at deterring predators, but not at deterring amphipods! Sometimes, an amphipod will grab one of these sea angels and carry it for protection-kind of like a living can of pepper spray.
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