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Opisthobranchia
(sea slugs)

of the eastern north pacific


By Ken Ashman, copyright © 2000-2015

In my slug hunts I've traveled throughout the Eastern North Pacific, from Mexico to Canada. I've made many friends, and learned much about the ocean along the way. These tiny creatures add immensely to my enjoyment of underwater photography. Every dive with a macro lens is like a treasure hunt. By gathering the fruits of my slug hunts here, my goal is to share what I've found, and continue learning. I invite your insights and input. This collection is a labor of love and a work in progress.




WITHIN Class Gastropoda there are two subclasses, the spiral-shelled animals of Prosobranchia, and the sea slugs of Opisthobranchia. Over three hundred different species of opisthobranchs are known to live in the eastern North Pacific. My images below represent 1/3 that number.




Order Cephalaspidea

The Bubble Shell or Head Shield (cephalic) opisthobranchs are primitive sea slugs with external shells and rolled rhinophores. In the family Aglajidae the shell is minimal and internal, but most others in this Order have large shells and can easily be mistaken for marine snails.


Aglajidae Family:

Navanax aenigmaticus
Navanax aenigmaticus, Family: Aglajidae, Order: Cephalaspidea
Navanax inermis
Navanax inermis, Family: Aglajidae, Order: Cephalaspidea




Order Sacoglossa

The Sapsuckers are herbivorous sea slugs. Most have rolled rhinophores, but otherwise many in this order strongly resemble nudibranchs. Sacoglossans store their worn-out teeth in a pouch called an ascus.


Oxynoidae Family:

Lobiger souverbii
Lobiger souverbii, Family: Oxynoidae, Order: Cephalaspidea
Oxynoe panamensis
Oxynoe panamensis, Family: Oxynoidae, Order: Cephalaspidea

Elysiidae Family:

Elysia diomedea
Elysia diomedea, Family: Elysiidae, Order: Cephalaspidea
Elysia hedgpethi
Elysia hedgpethi, Family: Elysiidae, Order: Cephalaspidea




Order Anaspidea

The name Anaspidea means "without head shield". These branchs are herbivorous algae eaters. They are related to the cuttlefish, squid, & octopus, and like squid and octopus can secrete a noxious fluid & ink mixture if molested. The Sea Hares are named for their superficial similarity to the European Hare. The rolled rhinophores and overall shape of most members of the Aplysiidae family certainly bring a hare to mind. Two members of the genus, Aplysia californica and its bigger cousin A. vaccaria, are the largest branchs in the ocean, the latter reaching a meter in length.


Aplysiidae Family:

Aplysia californica
Aplysia californica, Family: Aplysiidae, Order: Anaspidea
Phillaplysia padinae
Phillaplysia padinae, Family: Elysiidae, Order: Anaspidea
Aplysia parvula
Aplysia parvula, Family: Aplysiidae, Order: Anaspidea




Order Notaspidea

The Sidegills also have rolled rhinophores. Most have internal shells, but a few have hat-like external shells. The gills of the notaspideans project from the right side of the animal, and to varying degrees look like the plumes of a quill pen.


Tylodinidae Family:

Tylodina fungina
Tylodina fungina, Family: Tylodinidae, Order: Notaspidea

Pleurobranchidae Family:

Berthella californica
Berthella californica, Family: Pleurobranchidae, Order: Notaspidea
Berthella stellata
Berthella stellata, Family: Pleurobranchidae, Order: Notaspidea
Berthellina ilisima
Berthella ilisima, Family: Pleurobranchidae, Order: Notaspidea
Berthella strongi
Berthella strongi, Family: Pleurobranchidae, Order: Notaspidea
Pleurobranchus aerolatus
Pleurobranchus aerolatus, Family: Pleurobranchidae, Order: Notaspidea




Order Nudibrancia

The Order Nudibrancia is by far the largest, and is divided into four Suborders: Aeolidina, Arminina, Dendronotina, & Doridina.


Suborder Doridina

Goniodorididae Family:

Ancula gibbosa
Ancula gibbosa, Family: Goniodorididae, Suborder: Doridina, Order: Nudibrancia
Trapania goddardi
Trapania goddardi, Family: Goniodorididae, Suborder: Doridina, Order: Nudibrancia

Onchidorididae Family:

Diaphorodoris lirulatocauda
Diaphorodoris lirulatocauda, Family: Onchidorididae, Suborder: Doridina, Order: Nudibrancia
Acanthodoris hudsoni
Acanthodoris hudsoni, Family: Onchidorididae, Suborder: Doridina, Order: Nudibrancia
Acanthodoris lutea
Acanthodoris lutea, Family: Onchidorididae, Suborder: Doridina, Order: Nudibrancia
Acanthodoris nanaimoensis
Acanthodoris nanaimoensis, Family: Onchidorididae, Suborder: Doridina, Order: Nudibrancia
Acanthodoris rhodoceras
Acanthodoris rhodoceras, Family: Onchidorididae, Suborder: Doridina, Order: Nudibrancia

Polyceridae Family:

Limacia cockerelli
Limacia cockerelli, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia
Polycera alabe
Polycera alabe, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia
Polycera atra
Polycera atra, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia
Polycera tricolor
Polycera tricolor, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia
Tambja abdere
Tambja abdere, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia
Triopha catalinae
Triopha catalinae, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia
Triopha maculata
Triopha maculata, Family: Polyceridae, Suborder: Doridina, Order: Nudibrancia

Aegiretidae Family:

Aegires albopunctatus
Aegires albopunctatus, Family: Aegiretidae, Suborder: Doridina, Order: Nudibrancia

Dorididae Family:

Diaulula sandiegensis
Diaulula sandiegensis, Family: Dorididae, Suborder: Doridina, Order: Nudibrancia
Doris montereyensis
Doris montereyensis, Family: Dorididae, Suborder: Doridina, Order: Nudibrancia

Doris odhneri
Doris odhneri, Family: Dorididae, Suborder: Doridina, Order: Nudibrancia
Hoplodoris bramale
Hoplodoris bramale, Family: Dorididae, Suborder: Doridina, Order: Nudibrancia
Peltodoris nobilis
Peltodoris nobilis, Family: Dorididae, Suborder: Doridina, Order: Nudibrancia

Rostanga pulchra
Rostanga pulchra, Family: Dorididae, Suborder: Doridina, Order: Nudibrancia

Chromodorididae Family:

Cadlina flavomaculata
Cadlina flavomaculata, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Cadlina limbaughorum
Cadlina limbaughorum, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Cadlina luarna
Cadlina luarna, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Cadlina luteomarginata
Cadlina luteomarginata, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Cadlina sparsa
Cadlina sparsa, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Chromodoris macfarlandi
Chromodoris macfarlandi, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Chromodoris sphoni
Chromodoris sphoni, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Glossodoris dalli
Glossodoris dalli, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Glossodoris sedna
Glossodoris sedna, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Hypselodoris agassizii
Hypselodoris agassizii, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Mexichromis antonii
Mexichromis antonii, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Mexichromis porterae
Mexichromis porterae, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia
Mexichromis tura
Mexichromis tura, Family: Chromodorididae, Suborder: Doridina, Order: Nudibrancia

Dendrodorididae Family:

Dendrodoris behrensi
Dendrodoris behrensi, Family: Dendrodorididae, Suborder: Doridina, Order: Nudibrancia
Dendrodoris fumata
Dendrodoris fumata, Family: Dendrodorididae, Suborder: Doridina, Order: Nudibrancia
Doriopsilla albopunctata
Doriopsilla albopunctata, Family: Dendrodorididae, Suborder: Doridina, Order: Nudibrancia
Doriopsilla janaina
Doriopsilla janaina, Family: Dendrodorididae, Suborder: Doridina, Order: Nudibrancia




Suborder Dendronotina

Tritoniidae Family:

Tochuina tetraquetra
Tochuina tetraquetra, Family: Tritoniidae, Suborder: Dendronotina, Order: Nudibrancia
Tritonia festiva
Tritonia festiva, Family: Tritoniidae, Suborder: Dendronotina, Order: Nudibrancia
Tritonia pickensi
Tritonia pickensi, Family: Tritoniidae, Suborder: Dendronotina, Order: Nudibrancia

Dendronotidae Family:

Dendronotus albus
Dendronotus albus, Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia
Dendronotus diversicolor
Dendronotus diversicolor, Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia
Dendronotus iris
Dendronotus iris, Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia
Dendronotus rufus
Dendronotus rufus, Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia
Dendronotus frondosus
Dendronotus frondosus, Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia
Dendronotus sp.
Dendronotus sp., Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia
Dendronotus sp. 3
Dendronotus sp. 3, Family: Dendronotidae, Suborder: Dendronotina, Order: Nudibrancia

Hancockiidae Family:

Hancockia californica
Hancockia californica, Family: Hancockiidae, Suborder: Dendronotina, Order: Nudibrancia

Dotidae Family:

Doto amyra
Doto amyra, Family: Dotidae, Suborder: Dendronotina, Order: Nudibrancia
Doto sp.
Doto sp., Family: Dotidae, Suborder: Dendronotina, Order: Nudibrancia

Lomanotidae Family:

Lomanotus vermiformis
Lomanotus vermiformis, Family: Lomanotidae, Suborder: Dendronotina, Order: Nudibrancia
Lomanotus sp.
Lomanotus sp., Family: Lomanotidae, Suborder: Dendronotina, Order: Nudibrancia




Suborder Arminina

Arminiidae Family:

Armina californica
Armina californica, Family: Arminiidae, Suborder: Arminina, Order: Nudibranchia

Dironidae Family:

Dirona albolineata
Dirona albolineata, Family: Dironidae, Suborder: Arminina, Order: Nudibrancia
Dirona pellucida
Dirona pellucida, Family: Dironidae, Suborder: Arminina, Order: Nudibrancia

Zephyrinidae Family:

Janolus barbarensis
Janolus barbarensis, Family: Zephyrinidae, Suborder: Arminina, Order: Nudibrancia




Suborder Aeolidina

Flabellinidae Family:

Flabellina bertschi
Flabellina bertschi, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina cynara
Flabellina cynara, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina iodinea
Flabellina iodinea, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina marcusorum
Flabellina marcusorum, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina telja
Flabellina telja, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina trilineata
Flabellina trilineata, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina triophina
Flabellina triophina, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia
Flabellina vansyoci
Flabellina vansyoci, Family: Flabellinidae, Suborder: Aeolidina, Order: Nudibrancia

Eubranchidae Family

Eubranchus misakiensis
Eubranchus misakiensis, Family: Eubranchidae, Suborder: Aeolidina, Order: Nudibrancia

Aeolidiidae Family:

Aeolidia papillosa
Aeolidia papillosa, Family: Aeolidiidae, Suborder: Aeolidina, Order: Nudibrancia
Antaeolidiella indica
Antaeolidiella indica, Family: Aeolidiidae, Suborder: Aeolidina, Order: Nudibrancia

Glaucidae Family:

Facelina sp.
Facelina sp., Family: Glaucidae, Suborder: Aeolidina, Order: Nudibrancia
Hermissenda crassicornis
Hermissenda crassicornis, Family: Glaucidae, Suborder: Aeolidina, Order: Nudibrancia
Hermosita hakunamatata
Hermosita hakunamatata, Family: Glaucidae, Suborder: Aeolidina, Order: Nudibrancia
Phidiana hiltoni
Phidiana hiltoni, Family: Glaucidae, Suborder: Aeolidina, Order: Nudibrancia
Phidiana lascrucensis
Phidiana lascrucensis, Family: Glaucidae, Suborder: Aeolidina, Order: Nudibrancia
Facelina sp.
Facelina sp., Family: Glaucidae, Suborder: Aeolidina, Order: Nudibrancia

Tergipedidae Family:

Cuthona lagunae
Cuthona lagunae, Tergipedidae Family, Suborder Aeolidina, Order Nudibrancia
Cuthona sp.
Cuthona sp., Tergipedidae Family, Suborder Aeolidina, Order Nudibrancia




Bibliography

Rudman, W.B. 2005. The Sea Slug Forum - Australian Museum, Sydney. The species list and general topics sections of the Forum provide exhaustive resources on all opisthobranchs throughout the world.

Behrens, David & Hermosillo, Alicia. 2005. Eastern Pacific Nudibranchs: A Guide to the Opisthobranchs from Alaska to Central America. Sea Challengers. pp 1-24, 33, 37, 42, 49.

Behrens, David. 2005. Nudibranch Behavior. New World Publications, Inc.

Miller, Michael D. 2005. The Slug Site - The Branch of the Week (BOW) section provides excellent information on hundreds of opisthobranchs. Links to many branch-orientated websites.


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