BY: SINEAD MULHERN
It sounds mythical but it’s true. What many biologists consider to be one of the oldest living animals lives deep beneath the waters of the Hecate Strait off the northern coast of Vancouver Island.
The glass coral reefs (Hexactinellida if you want to get technical) that cover the tops of glacial moraines left from the ice age are about 9,000 years old – so old they’ve been nicknamed “Jurassic park submerged”.
These organisms stand eight stories tall and sprawl out over 1,000 square kilometres across the ocean floor. Although other smaller glass sponge reefs have been found submerged under the waters of West Vancouver, Sunshine Coast and Galiano Island, the Hecate Straight mass is the only known sizeable reef of this kind in the world.
It’s not surprising they’re considered one of the wonders of Canadian waters.
These dinosaur-era sponges were thought to be extinct until the late 1980s when they were discovered by an oceanographic survey of the Queen Charlotte Islands. The assumption that they were extinct wasn’t unwarranted. More than half of the reefs in this area had been destroyed by fishing trawlers—fishing boats that drag fishing nets along at mid water levels or along the bottom of the ocean’s floors. This discovery led to fishing closures in 2002.
The Hexactinellid is unique in that the entire structure is made up of one type of cell and entire blocks of the reef are actually just a large single cell. It produces both sexually and asexually and has an incredibly strong regenerative ability; wounded species are able to regenerate tissue as well as a skeleton. Sometimes if one piece breaks off and drifts, it will develop a new series of sponges all on its own.
It may seem that this coral reef is a robust, able-bodied organism. So why should we be concerned about its protection?
The glass reef’s structure is actually very delicate and thus, sensitive to sedimentation. That’s why physical disturbances, like the dragging of fishing nets for example, can cause serious damage.
This is a multi-cell organism that serves more than just itself. This ancient sponge is a home for several species and is a massive water purifier. Sponge reefs function by pumping water through their tubes to feed and remove waste. By pumping the ocean’s waters, they remove bacteria particles floating around at the same time.
As for the Hexactinellida, one sponge alone can filter up to 9,000 litres of water every day.