Bushy-Backed Nudibranch - Oceana Canada

Corals & Other Invertebrates

Bushy-Backed Nudibranch

Dendronotus frondosus


Frond Eolis, leafy dendronotid, branched dendronotus


North temperate oceans of the Atlantic, Pacific and Arctic


Rocky intertidal, subtidal, kelp and coral habitats


Feeds on microscopic creatures called hydroids


Order Nudibranchia; Family Dendronotidae


The bushy-backed nudibranch is a sea slug that comes in variable colours ranging from whites and pinks to yellows and reds. The name bushy-backed fits this species well, with rows of bushes and antennae along its back. These antennae are called rhinophores and can help determine the age of a nudibranch, kind of like the rings of a tree trunk. The more branches off the rhinophores and the more complex the branching is, the older the nudibranch. You can find these nudibranchs in the intertidal zones of Atlantic and Pacific Canadian waters.


The wide variety of colours within a singular nudibranch is one indication of this species. The environment, age and habitat in which they live can also affect the colouring of a nudibranch. Along the sides of bushy-backed nudibranchs, or the rim, there are up to nine pairs of gills. On the top of their bodies are tufts projecting out along with two antennae-like sensory projectors called rhinophores, which help them find prey and avoid predators. That’s why the name “bushy-backed” fits so well!

Juveniles can measure four to 30 millimetres long and are brighter and more patterned. If these nudibranchs live in deeper waters, their colouring tends to be duller with less pattern.

Bushy-backed nudibranchs utilize stinging cells called nematocysts that they obtain from the small jellyfish-like creatures called hydroids they eat. These cells are found at the end of the bushes along their backs and are used as defense mechanisms against predators.



Nudibranchs require a mate to reproduce, where they fertilize and then lay their eggs. The egg cases are laid in a ribboned spiral attached to food sources or rocks. Some nudibranchs lay a singular egg while others can lay more than 25 million! When the larvae hatch, they still have their hard shell. Microscopically small, they are free-floating and will move into deeper waters to develop. When they land on food sources, metamorphosis can begin when they drop their shell and crawl free. A fully grown adult will complete its life cycle by developing rhinophores and other sensory organs and starting the reproduction cycle over again. Nudibranchs live an average of one year, their entire life cycle of development taking only a few weeks to complete.



Nudibranchs can live in many different ocean habitats, including a variety of depths. Despite having no directed fishery, their habitat preferences can be impacted by destructive fishing practices. Bottom trawling is an example that involves dragging a heavily weighted net along the sea floor, scraping up and disturbing all life in its path. Bottom trawling does not discriminate in the species it catches or the habitat it destroys. Bottom contact gear off the East coast of Canada overlaps with bushy-backed nudibranch habitat.



The bushy-backed nudibranch has not yet been reviewed for the IUCN listing and we don’t know much about the population size of this species, or many other nudibranchs. Harmful fishing practices and threats such as climate change could put this species and others at risk of population decline if they are not mitigated.