Dendronotus dalli

Photograph taken at Nanimo, British Columbia, Canada, Sept. 1998

This striking nudibranch is a large stout, dendronotid, up to 14 cm in length with a white or pinkish white body and opaque white on the short-branched cerata. It is easily confused with the sympatric D. diversicolor Robilliard, 1970 which occasionally lacks its characteristic orange streaks and has only white. However, even large D. diversicolor have only 4 (rarely 5) pairs of cerata and a long tail, while D. dalli have 6-7 pairs of cerata and a short tail. The cerata of D. dalli have short, tertiary, fan-shaped branches.

This species is not common and is usually found below the thermocline in cold waters, from depths of 10-120 m. It lives in areas of moderate current where it feeds on the large sea fern hydroid, Abietnaria sp. It is largest and most numerous in October and November, declining in numbers in the spring and early summer. It spawns from February to August, the young being fully grown by November. The spawn is a loosely coiled white string with 1-9 eggs per capsule (Robilliard, 1970).

Dendronotus dalli is a boreo-arctic species ranging from the Barents Sea, Alaska (Bergh, 1879) to Puget Sound, Washington (Robilliard, 1970) and north eastern Russia (Volodchenko, 1955). It is capable of swimming when disturbed (Robilliard, 1970).

This animal was photographed by the web master, Mike Miller, at a depth of 23 m at Neck Point, Nanaimo, British Columbia, Canada, on September 27, 1998.

Webmasters Note: The above pic wouldn't have been possible without Sandra braving the thermocline and finding the animal. Believe me folks, it was cold!


Bergh, R.S. L., 1879. On the nudibranchiate gasteropod mollusca of the north Pacific ocean with special reference to those of Alaska. Proc. Acad. Nat. Sci. Philadelphia, pt. 1: 71-132; plts 1-8.

Robilliard, Gordon A. 1970. The systematics and some aspects of the ecology of the genus Dendronotus. The Veliger. 12(4): 433-479.

Volodchenko, N. I. 1955. Subclass Opisthobranchia, pp. 247-252; plt. 48. In: Atlas of the Invertebrates of the far eastern seas of the USSR, E. N. Pavlovskii (ed.). Transl. by A. Marcado, 1966.

Text courtesy of Sandra Millen

Sandra Millen

Department of Zoology
University of British Columbia
Vancouver, B.C., Canada, V6T 1Z4
Phone (604) 822-2087; Fax (604) 822-2416
Send Sandra E-Mail at
or visit Sandra's home page

Sandra is pictured at left along with Alan Grant and Mike Miller (webmaster)at the boat dock Nanaimo, British Columbia during a field trip to British Columbia Sept. 25th to the 27th, 1998. Sandra graciously set aside her busy schedule to join Alan and myself for a couple days of diving. Alan and I flew up and rented a car and rode the ferry over to Vancouver Island. The diving at this time of year is not unlike California Channel Islands diving. The water temperature hovered around 55 degrees f. depending on what depth you were at. The visibility although not spectacular, was more than sufficient for branching. There were more than enough branchs crawling about to take our minds off the water temp! Alan, who specializes in the video rendition of nudibranch activity was enthralled with all the new animals we encountered at British Columbia. Sandra's drysuit leaked a bit on the last day of diving, but other than that incident, Mr. Murphy took a back seat during the trip (for a change)! We also joined Marli Wakeling and other members of the Vancouver Underwater Photographic Society for diving at Dodd's Narrows, always a memorable dive!

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