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Living fossils

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Glass sponges are some of the oldest animals on earth dating back 580 million years.  


Common in the late Jurassic period, sponge reefs were believed to have gone extinct during or shortly after the Cretaceous period, about 40 million years ago.

While glass sponges are found all over the world in very deep water, they only exist shallower than 50 m in a few places in the world.

Bioherm forming glass sponge (or what we now call reefs) are known to occur only in British Columbia, and Howe Sound is exceptionally special in having the only known reef-forming sponges in water shallow as 120ft/35m.

Glass Sponge Timeline.JPG

Formation of glass sponge reefs

Glass sponges bodies are building out of silicon dioxide (i.e. glass) spicules.  These spicules attach to one another by fusing their tips, forming a rigid skeleton of tube like structures.

The reefs are created by new live growth attaching to old dead skeletal structures and proceeding to grow on top of them. These formations can continue to grow over each other in giant mounds for hundreds to thousands of years and can reach hundreds of meters tall.

When the older sponge dies off, it’s body breaks down and slowly becomes cemented into place by sediment that accumulates around it.  As time goes on new sponge grows on it’s own ancestors and that starts a new generation of sponge.

Sponge diagram.png

Important role in our ecosystem

The reefs are also filtering sea water at the rate of somewhere between 100,000 to 250,000 liters for every square metre every 24 hours, removing tons of bacteria from the water column. 


This is important because, like all life bacteria are made of carbon and when sponges eat bacteria the carbon is incorporated into their tissues creating a carbon sink.  


Much like a forest, sponge reefs help fight climate change by locking up carbon that might otherwise be in the atmosphere as CO2.

Home to more than 100 different animals

At-risk species like rockfish, lingcod, crustaceans like crab and shrimp use the reefs as a habitat.

Other residents include perch, forage fish, squat lobsters, sea stars, octopuses and nudibranchs to name a few.


Biggest threat to the glass sponge reefs

Many people are unaware of the diversity of life that exists on our sea floor.  Most think of it as a silt bottom or rocky rolling hills with some clams or crabs.  The biggest threats are:

Physical damage from fishing and anchoring

Lack of enforcement of existing regulations

Climate change


Our continued surveys help establish a baseline of the reefs 

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