Ringed Nudibranch (Diaulula sandiegensis)

By Scott Boyd

The ringed, brown spotted or leopard dorid (or doris) is a common visitor to many of our more popular dive sites.  The published name for this species is the San Diego dorid for the location it was first identified in 1863.  This dorid is commonly found on rocky shores below the low water mark to 110' deep and covers a range from Unalaska Island, Alaska to Cabo San Lucas, Mexico. 

Ringed Nudibranchs grow to about 4” and commonly feed upon breadcrumb, orange finger or white encrusting sponges.  They are easily identified by the ringed, dark spots found on their backs, which vary in color from white to yellow-brown according to their diet.  Their mantle has a velvety or fuzzy appearance, which is caused by very small bumps on their skin.

These nudibranchs typically lay a white spiral ribbon of eggs and attach it to an overhanging rock ledge. Each ribbon may contain up to 16 million eggs. Northern specimens (like ours) generally have more rings and spots than southern specimens (which can be found with no spots at all).  As with most nudibranchs, they can survive quite a bit of damage and regrow lost parts. They can even breathe through their skin if their gills are damaged or removed by a predator, which is a pretty neat trick.