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The virtuous medlar circle
thoroughly bletted



I like nudibranchs,

marine slugs with


by Hans Bertsch 
author of
"Everything you ever wanted to know about nudibranchs but were too timid to ask"
Hans at Bahía de los Angeles                                                              (copyright © Jim Mastro)
Some thirty-five years ago I was living at the Old Mission Santa Barbara, California, undergoing theological training to become a Catholic Franciscan priest.  There is a museum, down and across the canyon from the mission the Santa Barbara Museum of Natural History.  The director of the invertebrate zoology department was Mr. Nelson Baker. He smoked the biggest, thickest, longest, most humongous cigars available. And back in those days, he didn’t have to go outside under a tarp like California’s Governator today.

One of the staff members was a gentleman named Gale Sphon.  He sort of took me under his wing, allowed me to do some part time work at the museum, and in general helped a fledgling scientist. 

I would meet him at 3 am, and drive 50 miles or so northward to Punta Concepcion, where he had obtained special permission to collect. We had to pass through several locked gates. (Not only is it private property. It is adjacent to the Vandenburg military station, which frequently shoots rockets off across the Pacific to near Enewetak, to make sure their guidance systems work. Good idea.)

Here we'd be, using flashlights and lanterns, in pitch total blackness, wearing thigh-high rubber protective boots.

We'd squint and squeeze our eyeballs looking for 5-15 mm long slugs, often very well camouflaged.  Then, like the beginning scene of  “2001, A Space Odyssey,” there'd be a sudden moment of enlightenment as the sun rose and cast its light onto the tide pools. What had been only outlined by our narrow beams of light, was now brilliantly revealed in a full kaleidoscope of color. The algae reflected marvelous shades of brilliance — green, a blue glow, reds . . . The tide pools exploded in a brilliant rainbow destroying the darkness with iridescent coloration.

Then we started to find more and more nudibranchs (pronounced nu-di-brank)
in pinks, whites, yellows, oranges, blues, and all sort of shapes and sizes!

Gale and I would work the low tide site another hour or two, until the low tide became slack, and then reverse to come back in and cover our search areas. But we were satisfied, took our bucket of unidentified species back to the museum, and placed them safely in an aquarium. He'd go home and I'd return to the Mission to take a nap, until we would regroup later in the day to identify the species (unnamed, range extensions, well-known, etc.) with the museum’s microscopes (and Mr. Baker’s cigar).

That galvanized my interest in nudibranchs — to go from pitch blackness in the field to the elegant beauty of sunshine in the morning!

From there it did not take me long to really get hooked on nudibranchs. I took a summer invertebrate zoology course, had to do a research project — and guess what I chose?  The interactions between a nudibranch and its cnidarian prey!

The rest, as they say, is history.










The joys of discovery, and naming

I published my first scientific article (in The Veliger) in 1969, and named my first species of nudibranch in 1970.

.   Glossodoris baumanni                                                        (copyright © Hans Bertsch)


This was a real milestone, because it was the first species of nudibranch ever named that used scanning electron microscopy to illustrate the radular teeth! 

Radular teeth  
Glossodoris baumanni   (copyright © Hans Bertsch)







The species was collected while I was working at a marine station near La Paz, Baja California Sur, under the directorship of Dr. Rita Schaefer of the Los Angeles Immaculate Heart College. Just an aside, we stayed at the resort home of Bing Crosby!   (Ed: HB disingenuously puts an exclamation mark after this comment, but the connection between scientists [especially the slug-smitten subspecies nudibranchologist] and Bing deserves exploration.)

This species was named in honor of Father Anthony Baumann, my high school biology teacher who was so important in my formation as a biologist.

This recent article by Terrence Gosliner and myself, describes three species of Okenia nudibranchs from the eastern Pacific and the coasts of Baja California that we discovered and named.

Chromodoris marislae                                                               (copyright © Hans Bertsch)

The Chromodoris marislae is more common in the southern Gulf of California, although this photograph was taken at Bahía de los Ángeles.


Peltodoris nobilis                                                                   (copyright © Hans Bertsch)

This specimen of Peltodoris nobilis is intriguing, because the animal is usually yellow with black maculations, but it has been feeding on an orange sponge which affected its coloration.

Fascinating party animals

Biologically, nudibranchs and their related opisthobranchs are incredibly interesting animals — showing camouflage, chemical defenses, and all sorts of other defensive mechanisms.

Besides, they are beautiful, all dressed up ready to party!

Enjoy the animals, and their names!

Go take pictures of them!!!!!!!


Ed. note: Dr. Bertsch never mentions their rather amazing sex life here, but he does in his renowned exposé,

Everything you ever wanted to know about nudibranchs
but were too timid to ask




Dr. Hans Bertsch was born in St. Louis, Missouri, and received his Ph.D. from the University of California, Berkeley.  His many publications include technical works on archaeology, the philosophy of science, marine biology, and popular scientific articles on various natural history topics.  He has published in Mexican, Japanese, Israeli, German, Norwegian as well as U.S. journals.
    He has named over 30 species of nudibranchs, and has had several named in his honor.  His favorite is Bajaeolis bertschi, foudroyantly colored in various shades of pink and red, with white maculations.
    When not underwater, preparing lectures, or writing, he enjoys meandering the dirt roads of the Baja California peninsula, plant, animal, and rock art hunting.

AT: on Hans Bertsch  Although he has written many technical works of great erudition, his ability to communicate his love of the creatures he studies, and his respect for their world, are extraordinary. I was besotted with sea slugs before I read "Everything . . ." but with a bit of knowledge and a lot of his enthusiasm, my awe has grown, with lots more curiosity. He has infected me with the wish to know more, which is what science and communication should be all about. I hope he continues to explore, and to write more for those of us who have never seen a courting nudibranch, let alone seen a writer, let alone a scientist, so casually use the word "foudroyantly."
Dr. Hans Bertsch may be contacted at:
hansmarvida (at)
December 2007 news:
Just published, and fascinating, wherever you live:

A comprehensive field guide to the sponges, molluscs, echinoderms,worms, crabs, shrimps and other intertebrates of the Gulf of Mexico and adjoining Pacific coast from Mexico to Peru, featuring additonal photographs by Hans Bertsch.
Buy it here

Further irresistible reading:

Smitten by a slug

Nudibranch gallery

What's in a scientific name? Maybe your own

Nudi of the week is Phidiana lascrucensis

 Nudibranch of the week is Chromodoris lochi

The Slug Site, with the must-bookmark "opisthobranch of the week"

and the incomparable

Edu Snail

Upcoming in Scientists:
"Cognitive failure and behavioural determinism: The effect of nudibranch/opisthobranch confusion on the lay brain"
"Excitability in scientists: A study of exclamation marks"


The virtuous medlar circle

is part of
Anna Tambour and Others

"Why I like Nudibranchs" copyright © 2004 by Hans Bertsch    Photos except where indicated, copyright © Hans Bertsch
This essay appears here with thanks to Dr. Hans Bertsch, whose payment was less than a brass razoo.
His answer to the question "Why?" is the first in a series of invited pieces by people I find deliciously inspiring, always a hoot,
and whose interests are as intriguing as a  bletted medlar tastes. A.T.
The Virtuous Medlar Circle © 2004