Concerning the differences in the various genera, a quote from Bill Rudman's Sea Slug Forum-- "In Berthella, species do not grow as large as Pleurobranchus, the mantle is relatively smooth, the anterior mantle margin is weakly cleft, and the gill rachis is smooth. The reproductive system is triaulic and there is a penial gland. I don't think the tips of the rhinophores pulsate, and I think a unique feature of Berthella is the anus opening 'in front of the middle of the gill's suspensory membrane."
Berthella agassizi is a similar species but lacks the white specks, while Berthella stellata has an opaque white transverse bar across the dorsum.
It is interesting to note that the egg ribbon of B. strongi is a cylindrical coil , while B. californica's is wide and flat. Although rather rare to come across this species is has been recorded from central California to Punta Rosarito, Baja California, Mexico. Rudman reports one record from British Columbia.
Ken's shot here is amazing showing the rolled rhinophores, the eye spot, and if it were taken from the other side of the body, we'd be able to see the gill rachis.
"...My goal in doing nature photography is to tell the animal's story. I want
to show the creature as artfully as I can, within its natural setting.
There's a well-known maxim: "photographer's are artists who paint with
light". Techniques I learned doing weddings and portraiture work just
as well in U/W nature photography. Sharply angling the highlight-light
creates a tactile effect - makes it so you can almost feel the animal's
skin. Diving at San Miguel Island, I found this Berthella strongi
positioned on the edge of a large rock - allowing me to frame from
below. Looking up at the pleuromorph, the perspective is a slug's eye
view of the world..."
Equipment notes: Nikon CoolPix 5MP digital camera in Light & Motion Tetra housing, flat port, dual Sea&Sea YS90 strobes on 20" UltraLight arms & pivot grip. Image was taken 7/22/03 - ISO 100, F7.6, 1/500th
David W. Behrens
Pacific Coast Nudibranchs
Send Dave mail at firstname.lastname@example.org