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

Bring in the Clowns

In having noted the recent “Creepy Clown” absurdity in the far off periphery of my life, I thought I would share the beauty of the clowns abundant below the surface at this time of year – Clown Dorids.

Clown Dorids are a species of nudibranch (Triopha catalinae to 7 cm).

Nudibranchs are sea slugs with naked gills and those in the dorid suborder most often have their plume of gills on their posterior (around the anus in fact). See the orange frills in the Clown Dorids in these images? Those are their gills.

Clown Dorid; gills on right @Jackie Hildering.

Clown Dorid with gills are on the right. It’s “rhinophores”, by which it smells its way around, are on the left, atop its head. ©2016 Jackie Hildering 

Many dorid species fully retract their gills when disturbed. Clown Dorids can only partial retract their gills.

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That’s all!  Clown Dorids cannot fully retract their gills like most other dorid species.
@2016 Jackie Hildering.

Note too the beautiful “oral veil” with papillae that aid Clown Dorids in finding food.

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Image allowing a good look at the Clown Dorid’s oral veil. ©2016 Jackie Hildering.

Also unlike many dorids, Clown Dorids do not feed on sponges. They feed exclusively on bryozoan species; those crusty colonies of organisms often found on kelp.

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Clown Dorid likely feeding on Kelp-Encrusting Bryozoan (Membranipora serrilamella).
©2016 Jackie Hildering.

There were a particularly large number of Clown Dorids on my dive this past weekend with many egg masses.

Sea slugs are reciprocal hermaphrodites. This of course makes good sense as a reproductive strategy when you are a slow slug and your offspring hatch out to be plankton. Reciprocal hermaphrodites have both male and female sex organs whereby both individuals are inseminated and lay eggs = way more eggs!

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Clown Dorids that have found one another (relying on smell and touch) and maneuvering into the mating position. ©2016 Jackie Hildering.

Nudibranchs mate right side to right side. If you look very carefully in the photo below, you can see a bump on the individuals’ right side. This structure is the “gonopore” and is usually retracted. They lock onto one another with their gonopores and both become inseminated.

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Clown Dorids extending their mating organs and about to lock on right side to right side.
(Ochre Star beside them.) ©2016 Jackie Hildering.

The gonopore may be easier to see in this image.

Clown Dorid - note the "gonopore" on the right near the nudibranch's head. ©2017 Jackie Hildering.

Clown Dorid – note the “gonopore” on the right near the nudibranch’s head. ©2017 Jackie Hildering.

The egg masses of each species of sea slug look different. However, it is very difficult to discern the eggs masses of some closely related dorids. The ideal is to find an individual laying the eggs.

Clown Dorid egg mass. Every little dot is an egg that will hatch as plankton into the sea. ©2017 Jackie Hildering.

Clown Dorid egg mass. Every little dot is an egg that will hatch as plankton into the sea.
©2017 Jackie Hildering.

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Another perspective on Clown Dorid egg masses. ©2016 Jackie Hildering.

However, in all these years, I have never managed to get a photo of a Clown Dorid laying eggs. Dive buddy Paul Sim has though. See his great image below.

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Clown Dorid laying an egg mass. Note each little dot? That’s an individual egg! ©Paul Sim.

How’s that for bringing in the clowns?!

For you to enjoy, below are more non-scary clowns from this past weekend.

Clown Dorid near White-Spotted Anemone. ©2016 Jackie Hildering.

Clown Dorid near White-Spotted Anemone. ©2016 Jackie Hildering.

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Clown Dorid just below the surface in less than 5 m depth. Appears to be feeding on bryozoans.
©2016 Jackie Hildering.

More information:

  • Reproductive structures of Clown Dorids from the Sea Slug Forum – click here.
  • Colour and diet in Clown Dorids from A Snail’s Odyssey – click here.

One Response to “Bring in the Clowns”

  1. barbara bice

    These photos are fabulous and the one of the “clown” laying an egg mass leaves me breathless. Thanks for sharing something positive about clowns during this “frightening” time of year when everyone is nervous about the unbelievable election we are enduring in the US. Oh Canada…Oh Canada…cant wait to return to a land of dignity and good taste.

    Thanks for sharing. Be well and keep the blog photos coming.

    Reply

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