Nudibranchs and Sea Slugs of Guam (Part I)

For this inaugural Macronesia post, I'll start off close to home.  I have been living and working on the island of Guam, the largest of the Mariana Islands in the region of the Pacific known as Micronesia, for most of the last 6 years.  Over 485 species of nudibranch and sea slug are known from the waters of the Mariana Islands, though the vast majority are rarely seen and many more certainly remain undiscovered. 

This video portrays a random sampling of nudibranchs and sea slugs from Guam.   The first is a small dorid nudibranch that I have not been able to confidently identify, and have only seen this one time.  Cyerce elegans is an exquisite little sea slug whose body projections, called "cerata", magically camouflage it as tunicates and easily break off to allow it to escape predator attacks.  The fluffier portions of the body appendages along Bornella stellifer act as secondary gills.  Members of the genus Petalifera belong to a group known as "sea hares".  The striking Halgerda guahan is about the size of an egg, and is named for the Chamorro word for Guam, "Guahan".  Nudibranchs of the genus Aldisa are remarkable mimics of the marine sponges that they feed on.  The "spanish dancer", Hexabranchus sanguineus, is one of the largest and best-known nudibranchs, though few ever see them in their juvenile coloration.

You'll see through future posts that I've got an inordinate fondness for nudibranchs and sea slugs.