Join me in the cold, dark, life-sustaining NE Pacific Ocean to discover the great beauty, mystery and fragility hidden there.

Gold Dirona and Alabaster Nudibranch Egg Masses

This week, an egg hunt mystery FINALLY came to an end for me, coincidentally, just before Easter when many of you will be involved in egg hunts too.

I dare say however that my hunt involved vastly more beautiful eggs; that the hunt was much more challenging and –  ultimately, much more rewarding!

One of my very, very favourite things to do, satisfying my “The Marine Detective” nature, is to solve the ultimate “whodunit” and match sea slug species with their egg masses.

Every sea slug species’ egg mass is distinct, comprising a fascinating diversity of intoxicatingly beautiful shapes and patterns.

It delights me (for reasons I can’t fully explain) that for many sea slugs in the northeast Pacific Ocean, I am able to see an egg mass and immediately know which species laid it.

Often it has been easy to figure out due to clues like sea slugs often laying eggs on their food or . . . having the good fortune to find a sea slug in the act of laying their eggs.

But for YEARS, I have been unable to differentiate the egg masses of two of the most beautiful sea slug species in these waters – the gold dirona (Dirona pellucida to 12 cm) and the alabaster nudibranch (Dirona albolineata to 18 cm aka “white-lined dirona” or “frosted nudibranch”).

You’ll note that they are very closely related (same genus) and it thereby stands to reason that their egg masses would look very similar. Both also often lay their eggs on the same species of Agarum kelp and in all these years I have often found both species mating, but  have never found either species laying their eggs.

But then, this week . . . just when I was noting the abundance of both species, how many egg masses there were and wishing, WISHING, I could find just one of them laying eggs – my dear dive buddy Jacqui Engel waved me over and pointed out a gold dirona laying eggs.

Gold dirona laying eggs.

Click to enlarge. Gold dirona laying eggs (Dirona pellucida to 12 cm).
©2013 Jackie Hildering

I was so jubilant, I screamed underwater (yes, I am The Marine Detective for a reason, such things really do delight me to this degree). Finally!  Mystery solved, I would be able to differentiate the eggs of the two species.

But then, Nature was even kinder to me.

On the very same day on the very same dive, after so many years, I also stumbled across an alabaster nudibranch laying eggs!

Alabaster nudibranch laying eggs.

Click to enlarge. Two alabaster nudibranchs. One on right laying eggs (Dirona albolineata to 14 cm).
©2013 Jackie Hildering;

Disbelief! Joy! Manic photo-taking!

I think you may marvel at how very similar the masses are but the difference, at least to me is clear.

The “pieces” of the gold dirona’s egg mass are more compact and more like rice kernels.

Gold dirona laying eggs.

Close-up. Click to enlarge. Gold dirona laying eggs (Dirona pellucida to 12 cm).
©2013 Jackie Hildering

The segments of the albaster nuidbranch’s egg masses are more scallop-edged and diffuse.

Alabaster nudibranch laying eggs.

Close-up. Click to enlarge. Alabaster nudibranch laying eggs (Dirona albolineata to 14 cm).
©2013 Jackie Hildering;

If you have read to this point – thank you!

Likely we are kindred in our love of marine biodiversity and the beauty that is sea slugs.

For as much as I love chocolate Easter eggs, I would forego them for the rest of my existence if it would allow my appetite for marine mysteries to be further satisfied!

7 Responses to “Gold Dirona and Alabaster Nudibranch Egg Masses”

  1. paul whalennewcastle

    Beautiful pics …waiting for the tabletop book .


  2. Donna

    Who knew something called a “slug” could be so beautiful!! Thank you for your enthusiasm.

  3. Anonymous

    Happy Easter,glad you got the kind of eggs you wanted,man’ that bunny sure knows his people.

  4. Maradel

    Thank you so much for this posting, which helps enlighten those of us who find these eggs and wonder whose they are!


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