Here’s an undersea beast that I saw for the very first time on August 30, 2015 while diving at Santa Catalina Island off the coast of southern California. Known as the leopard dorid (Jorunna pardus), it is a nudibranch, or sea slug, in the family Dorididae. It gets its name from the obvious leopard-like spots on its back. This species was only first described in 1981, and even as recently as 2005 nothing was considered to be known about its biology.
The dark spots are composed of sensory structures called caryophyllidia. That is an extremely fancy word that breaks into the Greek roots karyo-, which denotes the nucleus of a cell, and -phyll, which means leaf. Not being an expert in nudibranch anatomy, I’m not sure exactly why these structures would be called “nucleus leaves.” But that’s your fun excursion into etymology for the day.
Enjoy the photograph.