Beauty in the Mud

The sun finally chased the rain away down on the canal today.

However, the canal water is still mainly missing and we (the boat and me) are still somewhat in the mud... but as the sun comes out from behind the storm clouds, some magic happens and some unexpectedly complex biology pops up. Here are some images.

First the rain

Then the rainbow

Then the sun picks out glinting in the mud:

something shiny

The shine is provided by the mother of pearl insides of the Swan Mussels 

The swan mussels have a remarkable life cycle. They release their larvae into the water where they latch onto certain fish. They live attached as external blood-sucking parasites before falling to the bottom after a few weeks and then growing into these adult mud-dwelling shell-fish. But the story does not end here. 

Swan mussels normally live buried in the mud apart from their inhalent and exhalent siphon tubes. They are filter feeders and the siphons are used for sucking water in and pushing it back out again so the animal can remove food particles from the water stream, 

Now, one main host for mussel babies is a little fish called the bitterling and the bitterlings females push their eggs into the swan mussel via the inhalent siphon. The male bitterling then does likewise with his sperm and the eggs are fertilised. The eggs  develop inside the swan mussel where they are protected until small fishes hatch and swim away. A remarkably complex little bit of biology and something of a two-way street for the big mollusc and the little fish where both benefit. And all this has been going on down in the mud below the murky canal waters where we cannot see it!.

But something else has also been lurking in the deep....

Zebra mussels in the cracks in the old canal walls

And returning to the 'mystery in the mud'..... the other smaller bivalved molluscs attached to the walls and other hard structures in the canal (and now exposed by the absent water) are zebra mussels (see above and below). 

Unlike the swan mussels these are invaders that arrived in the UK some 180 years ago from the Caspian Sea and sometimes cause problems when they block pipes or conduits. Many are now gaping open - they have died - but they are remarkably tenacious and can survive for some seven days out of water. The female produces a million eggs a year - there is a mass die-off now in my little bit of canal but they will be back. .