petasma
/pɛˈtazmə/ /pɪˈtazmə/Zoology
noun
A copulatory appendage attached to the first pair of pleopods in some male crustaceans, especially penaeid shrimps.
Origin
Late 19th century. From ancient Greek πέτασμα something spread out, used by Aristotle of the feelers of the polypus from πεταννύναι to spread out + -σμα, extended form of -μα.