All Photos courtesy of John Greenamyer
Nudibranch Egg Color
One of our dedicated slug-o-philes, Mr. John Greenamyer, sent us a note asking "is there a factor that causes the color of Nudi eggs?"
We know a lot about sea slug reproduction and egg and larvae development, but there is little factual information about why the colors. I am aware of no actual proof only supposition, based on a few characteristics. One theory is that egg color comes from the food they eat. This isn't always the case however.
In some species the egg color is similar to the critters own body color, but in others the eggs are a totally different color.
Brightly colored eggs are often caustic and poisonous like the adult that laid them. This is aposomatic (warning) coloration, while other species lay very cryptic eggs, hidden on their food substrate. Examples of the latter would be many of the sacoglossids.
What we do know is that the number of eggs laid can vary from as few as one or two in primitive species to as many as 25 million reported in some sea hares. Additionally, the number of eggs forming a mass directly relates to the nature of a species' larval development (at one extreme planktotrophic species laying thousands of small eggs, while direct development species at the other extreme lay fewer large eggs); the size of the individual laying the eggs; whether it is the first, second or third spawn laid; and the nutritional state of the individual.
John Greenamyer has been diving some thirty years with a macro u/w photography pursuit using both still photography and video. His favorite diving areas are PNG and Indonesia with an emphasis on PNG, especially the Milne Bay region so popularized for its "muck" photographic opportunities. On many of these trips, he was in the company of Roger Steene, Neville Coleman and Ali Hermosillo on the CHERTAN!
John has been kind of a mentor to me when it comes to super macro sea slug videos! John is also a great supporter of the site and I look forward to diving with him again in the future!
Congratulations John, your naming is an honor richly deserved!