Nudibranchs and other Sea Slugs

Order Systellommatophora, Aplysiidae,

& Pteropoda; Superorder Sacoglossa

Onchidiidae

Deception Pass State Park, WA Petersburg, AK, intertidal Seal Rock, OR, intertidal

Onchidella carpenteri (Binney, 1860)
Leather Limpet
intertidal central California to northern Alaska size to 15mm
Can be found with a bit of hunting. The species is small and blends into its environment. Despite its name, it is not closely related to limpets. It is air breathing and lives in the high intertidal zone.
(synonym - Onchidella borealis)

Clionidae

Rich Passage, WA, subtidal Oceanside OR, intertidal

Clione limacina (Phipps, 1774)
Sea Angel
pelagic to 600m size to 80mm
all northern cold and temperate seas,
locally - northern Mexico to Arctic
This pteropod species swims through the water and can be very abundant. It is carnivorous and feeds on other pteropods.
(previous name - Clio limacina)

Cymbuliidae

Friday Harbor, WA, subtidal
Corolla spectabilis Dall, 1871
Spectacular Corolla or Sea Butterfly
pelagic size to at least 8cm
eastern Pacific Ocean; western Atlantic Ocean; Hawaii; Japan; Mediterranean Sea
This species "flies" through the water. Rather than an external shell, it possesses a gelatinous internal pseudoconch. It can be very abundant in the water and occasionally the gelatinous pseudoconch can wash up on the beach.

Phyllaplysia taylori Dall, 1900
Zebra Leafslug or Taylor's Seahare
intertidal to subtidal on the eel grass Zostera
southern California to central BC size to 8cm
Look near the base of Zostera, between the
blades, to find this species. It is well-camouflaged.
(synonym - Phyllaphysia zostericola)

Hermaeidae

Turn Island, WA, subtidal
Aplysiopsis enteromorphae
(Cockerell & Eliot, 1905)
Enteromorpha-eating Sapsucker
intertidal to shallow subtidal size to 25mm
southeast Alaska to northern Mexico
This tiny species is difficult to spot. It feeds on filamentous green algae. It may be yellowish to dark brown with greenish-black patches. The cerata usually have dark lines.
(previous name - Aplysiopsis smithi)

Rich Passage, WA, subtidal Hazard Canyon, CA, intertidal

Hermaea oliviae (MacFarland, 1966)
Olivia's Sapsucker
intertidal to shallow subtidal northern Mexico to southern BC size to 10mm
Its small size makes it difficult to find. Search for it on filamentous green algae. The body is decorated with mahogany colored lines.
(previous name - Aplysiopsis oliviae)

Limapontiidae

Oak Bay, WA, intertidal
Olea hansineensis Agersborg, 1923
Hansine's Egg Eater
intertidal to shallow subtidal size to 13mm
southern California to southern Alaska
This specimen was found feeding on Haminoea vesicula eggs.
This species is very small and hard to spot.

Rich Passage, WA, subtidal
Placida dendritica (Alder & Hancock, 1843)
Branched Sapsucker
intertidal to shallow subtidal size to 8mm
central Mexico to Alaska
Its small size makes it difficult to find. The light colored body is marked with branching greenish lines.

Rich Passage, WA, subtidal Seal Rock, OR, intertidal

Stiliger fuscovittatus Lance, 1962
Brown-streaked Sapsucker
intertidal to subtidal size to 15mm
north Mexico to Ketchikan, AK
This small species is often overlooked among the red filamentous alga. It has a pale colored body with reddish-brown spots and irregular lines.

Plakobranchidae

Dyes Inlet, WA, subtidal Otter Crest, OR, intertidal

Elysia hedgpethi Marcus, 1961
Hedgpeth's Sapsucker
intertidal to shallow subtidal size to 35mm
northern Mexico to southern BC
It is infrequently seen intertidally. It is
well-camouflaged on the dark plants it prefers.

Click on photo to enlarge. Scale line in photo equals 1cm unless otherwise specified.

* Species which are the most commonly encountered nudibranchs on the beach.