Red rhinophores (front antennae with scent and/or taste receptors used to sense their food).
Bright orange cerata (outgrowths on their backs that contain part of their digestive tract).
About 2.75 inches in length.
British Columbia, Canada to the Galapagos Islands.
Found from the intertidal (area of shoreline covered at high tide and uncovered at low tide) to depths of 130 feet.
Like many other sea slugs, the Spanish Shawl is a hermaphrodite (each animal has both male and female sex organs).
Self-fertilization rarely occurs; two Spanish Shawls will mate and both will lay long gelatinous pinkish-orange ribbons of eggs and both will deposit sperm on the others’ egg cases.
Mating most often occurs in late fall.
After about a week, the eggs hatch into free-swimming veligers that eventually settle to the bottom.
Feed on a species of hydroid that contains a toxin called astaxanthin. The astaxanthin gives Spanish shawls their brilliant pigmentations of purple, red, and orange.
Also eat sea anemones, gorgonians, bryozoans, and mollusk eggs.
The navanax, a different sea slug that is immune to the stinging nematocysts (stinging cells on their cerata) of the Spanish shawl.
Unlike most nudibranchs that crawl on a surface, Spanish shawls can swim in the open water by contorting their body back and forth in a U-shape. This is where they get their name, because they look like a Spanish flamenco dancer while they swim.
They can often be found by first spotting the long ribbons of their pinkish-orange eggs.
Nudibranchs have sacs at the end of their cerata (orange outgrowths on the top of their body) that can contain stinging nematocysts (stinging cells). The stinging nematocysts come from ingesting their cnidarian (sea anemones and hydroid) prey. Nudibranchs not only don’t get stung by these cnidarians, but they can take these nematocysts and use them for their own defense!
Sources: Thoughtco.com; seaslugforum.net; Cabrillo National Monument; California Diving News
Photo: Derek Tarr
The Lyons Lab at Scripps Institution of Oceanography is studying nudibranchs to learn about their genomics, development, and evolution.