An Undersea Leopard

Another Lens on Life post from Chuck Kopczak, PhD

10/5/2020
A pale yellow slug-like creature, covered in spotty reddish splotches, on a colorful underwater rock
Chuck Kopczak, PhD

The leopard dorid, Jorunna pardus, is a sea slug found off the coast of Southern California.

This photo was taken with a Canon EF100 mm f/2.8 macro lens with both a 25 mm and a 12 mm Canon EOS extension tube on a Canon EOS 5D Mk. III in an Ikelite underwater housing., Light was provided by two Ikelite DS-161 strobes in eTTL exposure mode. The exposure was set to 1/60 sec. at f/11 and ISO 200.

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.