Coffin Box Bryozoan

Membranipora membranacea

Do you think you have discovered an aquatic invasive species?

  1. Do not return the species to the water.
  2. Note the exact location (GPS coordinates) and the observation date.
  3. Take photos.
  4. Take note of identifying features.
  5. Report an Aquatic Invasive Species, depending on where you are.
  6. What you can do to reduce the risk.
Coffin Box Bryozoan. Also called: Lacy Crust Bryozoan

Coffin Box Bryozoan. Also called: Lacy Crust Bryozoan

The Coffin Box is a 'bryozoan', a type of tiny invertebrate animal. Although each individual animal is tiny, it lives together with others in large colonies. The coffin box feeds by filtering sea water through its body.

Identifying features

  • Tiny filter feeders (zooids);
  • Forms white-colored encrusting colonies of hundreds to thousands of small rectangular or 'coffin' shaped individuals;
  • Each individual animal is less than 1mm in length;
  • Colonies of coffin box can grow 10 cm or more in width;
  • The colony has a rough texture;
  • Colonies are round and made up of many small rectangular "cells".
  • Colonies cover surfaces of rockweed, kelp, and even boat hulls;
  • Typically, colonies of coffin box are circular in shape, but they can form irregular shapes when crowded by other colonies.

Similar species (native)

Hairy Sea-Mat (Electra pilosa)

Coffin Box Bryozoan can be mistaken for the Hairy Sea-Mat, a native bryozoan. It also forms white sheets on seaweed, but it can be distinguished from the coffin box by its star-shaped colonies, hairy extensions and small oval-shaped individuals.

Where it has been found

Was first found in eastern Canada, Nova-Scotia, in the early 1990's and in the Gulf of St. Lawrence, Quebec, in 2003. Coffin box was first observed in Newfoundland and Labrador in 2002. It has already become a prominent part of kelp beds throughout coastal areas of the island. It is now established in Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland.

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan


This species can be found in shallow subtidal waters from the surface down to a depth of ten meters, on kelp and other seaweed, rocks, boat hulls, and other surfaces and organisms. Grows best in areas with strong currents or good tidal water exchanges.

Coffin Box Bryozoan distribution in Gulf region

Coffin Box Bryozoan distribution in Gulf region
Click image to enlarge

Ecological and economic impacts

Kelp beds are important because they are highly productive marine habitats. They are a source of food for many animals, as well as a hiding place for many species of fish and invertebrates.

In the fall, colonies of coffin box can entirely cover a blade of kelp, causing it to become brittle and eventually killing it. The presence of coffin box on kelp can starve kelp by preventing it from absorbing nutrients. Coffin box can reduce the amount of light available for photosynthesis, which may affect growth rates. It disturbs kelp ecosystems, and promotes establishment of invasive plants, such as Codium. It can also reduce the kelp's ability to reproduce by preventing the release of spores. Overall, these effects can decrease the abundance of kelp, so the spread of coffin box in Newfoundland and Labrador may permanently alter our kelp beds and affect biodiversity along our coasts.

Origins and mode of arrival

Coffin Box Bryozoan is native to the North Pacific Ocean from Alaska to Baja, California, and throughout the temperate Northeast Atlantic Ocean.

Mode of dissemination

Coffin Box Bryozoan has a relatively continuous distribution in Nova Scotia, indicating that its spread is mostly from larval dispersal. Larval abundance varies temporally and spatially and is influenced by water column stratification, with larvae occurring in higher abundances in the higher, shallower, fresher layer above the pycnocline.

Coffin Box Bryozoan can be picked up easily in ballast water because of its dispersive larval phase. It is also known to raft on dislodged kelp and has been found encrusted on drift plastic. This species can successfully invade new areas dues to its short reproductive cycle, fast growth rates, and absence of predators and competitors.

Coffin Box in Newfoundland and Labrador Waters

Discovery and Survey findings

Coffin Box Distribution in Newfoundland Waters

Click image to enlarge.

Distribution Location and Bay

Argentia: Placentia Bay

Arnolds Cove: Placentia Bay

Bar Haven: Placentia Bay

Bay Bulls: Eastern Avalon

Bay East: Placentia Bay

Belleoram: Fortune Bay

Bird Cove: Northern Peninsula West

Bonne Bay: West Coast

Boxey: Fortune Bay

Burin: Placentia Bay

Burtons Cove: Fortune Bay

Cape Broyle: Eastern Avalon

Codroy: Southwest Coast

Come by Chance: Placentia Bay

Coxs Cove: West Coast

Daniels Harbour: Northern Peninsula West

Darbys Harbour: Placentia Bay

Davis Cove: Placentia Bay

Eastport: Bonavista Bay

Foxtrap: Conception Bay

Gaultois: Hermitage Bay

Grand Bay West: Southwest Coast

Grandois: Northern Peninsula East

Green Island Cove: Northern Peninsula West

Harbour Breton: Fortune Bay

Harbour Grace: Conception Bay

Harbour Mille: Fortune Bay

Hearts Content: Trinity Bay

Hermitage: Hermitage Bay

Holyrood: Conception Bay

Jean de Gaunt: Placentia Bay

Lark Harbour: Bay of Islands

Lewisporte: Notre Dame Bay

Little Bay: Placentia Bay

Little Bay: East Fortune Bay

Little St Lawrence: Placentia Bay

Logy Bay: Eastern Avalon

Long Pond: Conception Bay

Marystown: Placentia Bay

Norris Point: Bonne Bay

North Harbour: Placentia Bay

Paradise Sound: Placentia Bay

Petite Forte: Placentia Bay

Piccadilly: Port au Port Bay

Placentia: Placentia Bay

Pools Cove: Fortune Bay

Port au Choix: Northern Peninsula West

Port aux Basques: Southwest Coast

Port Saunders: Northern Peninsula West

Powell Cove: Bonavista Bay

Presque Harbour: Placentia Bay

Raleigh: Pistolet Bay

Red Bay: Labrador Coast

Red Harbour: Placentia Bay

Riverhead: St. Marys Bay

Rose Blanche: Southwest Coast

Round Harbour: Notre Dame Bay

Salamander Point: Fortune Bay

Salmonier Cove: Connaigre Bay

Seal Cove: Connaigre Bay

Southern Harbour: Placentia Bay

Spanish Room: Placentia Bay

St Georges: St Georges Bay

St Josephs: Placentia Bay

Summerford: Notre Dame Bay

Swift Current: Placentia Bay

Terra Nova: Bonavista Bay

Three Rock Cove: Port au Port Peninsula

Torbay: Eastern Avalon

Vitters Cove: Trinity Bay

Westport: White Bay

From June to November 2008, a survey for coffin box was conducted along the west coast of Newfoundland and the southeast coast of Labrador. This survey was a partnership between Memorial University of Newfoundland, Fisheries and Oceans Canada, Institute for Biodiversity, Ecosystem Science and Sustainability, the Department of Fisheries and Aquaculture, and the Fish, Food and Allied Workers Union. The largest populations of coffin box were found in the Bay of Islands and Bonne Bay. North of these locations, the amount of coffin box on kelp decreased, with the smallest populations observed along the Strait of Belle Isle. During the entire survey, the greatest number of colonies of coffin box on kelp was observed in the fall of 2008.

In September and October of 2009, another survey found many colonies of coffin box on kelp at North Harbour and Arnold’s Cove and a few individual colonies at Eastport, Red Harbour, Holyrood and Bay Bulls.

Controlling abundance

Coffin box can spread over large distances by releasing larvae, which are carried by ocean currents. They can also be spread through human activity. Coffin box has been observed on boat hulls, growing on the kelp that is attached to the hull. To help control the spread of this aquatic invasive species, regularly clean and disinfect boats and boating gear.

For further information


  • Burridge, M. 2012. Biological synopsis of the Lacy Crust bryozoan (Membranipora membranacea). Can. MS Rpt. Fish. Aquat. Sci. 3006: iii + 25p.
  • Caines, S. and P. Gagnon. 2010. Population dynamics of the invasive bryozoan Membranipora membranacea along subarctic and temperate longitudinal and latitudinal gradients. Newfoundland and Labrador Aquatic Invasive Species Workshop. St. John’s, NL.
  • Chapman, A. S., R. E. Scheibling, and A. R. O. Chapman. 2002. Species introductions and changes in the marine vegetation of Atlantic Canada. Pages 133–148 in R.Claudi, P. Nantel, and E. Muckle-Jeffs, eds. Alien invaders in Canada’s waters, wetlands, and forests. Natural Resources Canada, Canadian Forest Service, Ottawa.
Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

Coffin Box Bryozoan

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