Porifera

Porifera diverged early off the evolutionary tree from the last common ancestor of all other animals. Porifera are multicellular organisms with bodies full of pores and channels allowing water to circulate through them, thus removing wastes, and obtaining food and oxygen. They do not have any organized nervous, digestive, or circulatory systems but they sport “do-it-all” cells that can move around their body and become any type required for living processes.

Sponges

Although seemingly bizarre creatures, sponges are actually very simple multi-celled organisms. Their basic structure lacks any nervous, digestive, or circulatory systems; but instead consists of densely porous flesh and a series of inner “tubes” working together to pump water through the organism. By this means, the sponge is able to filter feed very effectively. They may consume any number of items found in the water they filter, from microscopic bacteria to larger plant particles.

This simple structure is supported by a “skeleton”; a series of spine-like projections that form a loose network throughout the organism. These skeletons are highly important in identifying the various species of sponges and are often the only way to distinguish them correctly. In the NWT, there are few species of sponges (eight known species). All are ocean-dwelling except the freshwater lake sponge (Spongilla lacustris), so far found in a lake near Inuvik and expected to be present in other lakes in the NWT.

No new species or changes in ranks have occurred since 2016. Many of the common names have been updated to match names used across Canada.