SPONGES
- LAKE ERIE CENTRAL BASIN - AVON POINT
I have tried
to figure out why sponges interest me so much. I think there are two reasons;
one, sponges are incredibly ancient creatures, existing from Cambrian times,
some 400 million years ago, and two, their whole body plan is radically
different from any other animal on earth. They are an amazingly successful
group of animals if one considers the countless number of animals that
have had there brief day in the sun and have become extinct. It is easy
to imagine that our species too may someday no longer walk on the earth
but the sponges will still be here.
The above photo
is of a green sponge growing in the center of a large rock and a smaller
sponge growing on the rock's edge. The larger sponge is about 6 inches
in diameter. The most important point to realize is that this green mat
is one animal. Looking closely at the photo below you can see holes in
the mat. These holes are the exhalant opening. Scattered over the whole
surface of the sponge are much smaller inhalant openings. The sponge is
one big pumping machine, taking nutrient rich water in, removing the nutrients
and pushing the depleted water out. What I like about the upper photo is
that it shows the struggle the animals and plants have in finding and maintaining
a place to live on. The laison, which I wrote about earlier in this report,
is the brown stuff surrounding the sponge. While the Zebra mussels found
all along the rock's edge can live if the laison grows over it the sponges
cannot. But sponges will kill Zebra mussels if they grow over them. The
rock is one constant battleground for living space.
The reason the sponges are green is that some sponges
when they grow in areas that receive sunlight are able to form a symbiotic
relationship with algae.The sponge is able to get nutrient from the waste
products generated by the algae, what the algae gets, other than a place
to live, I'm not sure of.
The photo below is of a sponge going into gemmule
body formation. In the Fall, as the Lake water temperature begins to drop,
the sponge starts to encapsulate cells in a hard cyst that will act like
seeds and allowing the sponge to survive the winter and also some of the
gemmules will break off and spread the sponge to new areas.
Below, a large green sponge
growing on two sides of a rock (the sponge covers a 2 feet by 1 foot area).
I don't know whether sponge species
growing in the Lake are bioluminant, but they do seem to glow. At left
are a green and a yellow sponge.
