Dendronotus frondosus

Geographic Range

D. frondosus can be found all around the British Isles. The species range extends southwards to the Atlantic coast as far south as France; eastwards to Canada and the United States as south as new Jersey, and the Pacific coast of Canada and United States as far south as Los Angeles; and northwards into the Arctic circle.


D. frondosus are part of the bottom creepers that live in cold northern seas.

Physical Description

This species of nudibranch is highly variable in colour and has been thought to be a collection of several species. They may have white or mottled coloring with yellow, red or brown pigment. There may be up to nine pairs of gills along the pallial rim, which is the mantle. They have gills, oral veil and rhinophore sheaths, antenna-like organs, that are extended to form branched processes. Adults of this species may grow to 100 mm in length. The key distinguishing characteristics of this species are the large arborescent gills arising from the mantle edge and the arborescent processes on the edge of the rhinophore sheaths. The head is blunt with six branched projections extending forward. A striking feature is the two rows of 5-8 bushy projections along the back. (Amos and Amos 1985)


Dendronotus frondosus is hermaphroditic. The larval stage of the development is asymmetrical, although the adults show bilateral symmetry.


This species of nudibranch seems to writhe its body to swim, but it also moves its lacy cerata, for which it was named, to slowly move its body across the bottoms of the cold seas.

Food Habits

D. frondosus feeds on a variety of hydroids. The younger juvenille members of the species typically feed on calyptoblastic hydroids of Obelia, Halecium and Sertularia cupressina & Dynamena pumila . The adults usually feed on the gymnoblastic hydroids of the genus Tubularia.

Economic Importance for Humans: Positive

There are no known positive benefits of this species to humans.

Economic Importance for Humans: Negative

There are no known negative effects of this soecies to humans.

Conservation Status

Other Comments

The bushy-backed sea slug incorporates nematocysts that it obtains from the hydroids it eats, for its own defense. These are located at the ends of the projections (cerata) running down the dorsal side of the animal.


Kristin Cordz (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.


Arctic Ocean

the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map


Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.


1999. "Encyclopædia Britannica Online." (On-line). Accessed February 24, 2000 at

Amos, W., S. Amos. 1985. The Audubon Society Nature Guide: Atlantic and Gulf Coasts. New York: Afred A. Knopf.

Picton, B., C. Morrow. November 1, 1995. "Nudibranchs of the British Isles (Based off the book: A Field Guide to the Nudibranchs of the British Isles)" (On-line). Accessed February 23, 2000 at

Rudman, B. 1998. "Sea Slug Forum (An Australian Museum)" (On-line). Accessed February 21, 2000 at