>>41020624
my interesting fact is that there is a clade of barnacle-related crustaceans called facetotectans which are known exclusively from their free-swimming larval stage, called y-larvae. what these y-larvae grow into upon adulthood and how they feed or reproduce isnt known. however recent experiments using growth hormones have shown that upon being induced to metamorphose, the shrimp-like y-larvae develop into a completely soft-bodied, slug-like form with extremely simplified anatomy, which researchers have called the ypsigon. this is similar to the maturation process in many parasitic marine crustaceans, which has led the researchers involved to theorise that facetotectans spend their adult lives as internal parasites of as-yet unknown host species