Dancing with the Spanish Shawl

January 30, 2018 Posted by: Andrew Rosales

Among the shifting tides of Cabrillo National Monument’s intertidal bench lives a colorful little sea slug, the Spanish Shawl (Flabellinopsis iodinea). This is a species of aeolid nudibranch that is so striking to behold, it will stop you in your tracks! The body of the Spanish Shawl is translucent purple with bright orange cerata rising from its back. This nudibranch can be up to 7cm in length and 1.3cm wide. The rhinophores are a deep red and used for navigation to help find mates and prey. The slugs feed on tiny hydrozoan colonies growing on kelp and will acquire the stinging cells from their prey to use in their own cerata as a defense against predation in a process known as chemical sequestration. 


NPS Photo/Nicole Ornelas - Spanish Shawl nudibranch crawls around on the rocky bottom of the tidepools.

The Spanish Shawl is also capable of swimming. When they release from the rocky substrate, they fold their foot along the midline to increase their lateral surface and then begin bending back and forth in a rhythmic fashion propelling themselves through the water. 

Spanish Shawl lives subtidally to depths up to 27 meters. This nudibranch, like many other sea slugs, is hermaphroditic. However, self-fertilization rarely occurs and mating will occur only when another nudibranch is in the vicinity. The reproductive organs are located on the right side of the nudibranch and both will pass sperm sacs through their genital pore to fertilize eggs. The eggs are deposited on kelp in a gelatinous, pink ribbon-like masses in late fall.


NPS Photo/Nicole Ornelas - Spanish Shawl nudibranch crawls around on the rocky bottom of the tidepools.

So, as you explore Cabrillo’s intertidal zone keep an eye out for this flashy nudibranch. The purple and orange fringe (cerata) combination will have you clapping a Flamenco rhythm with excitement in no time!

Rocky Intertidal, Gastropods, Sea Slugs