Friday, April 4, 2014

Wood Frog Eggs Hatching

Wood Frog egg masses are falling apart and the developing larvae are breaking through the egg membrane into open water.  Even though they have left the egg, the larvae are not yet free swimming.  Most just flutter to the pond bottom where they will rest for the next couple of days.  During this time they will use up the remaining yolk in their egg sack as they develop into a more typical tadpole shape.

Some egg clusters lost their globular shape and floated about on the water’s surface.  This did not seem to affect hatching at all.  Even so, there were several larvae that emerged on the upper surface of the raft and seemed in danger not making it down into the water.

Other egg clusters fell to the pond bottom.  No matter where they ended up, all of the egg masses produced healthy larvae.

Egg masses laid a little later in the season were still in the early stages of development.  The pond was ice covered on many mornings during the past two weeks.  I imagine the cold temperatures played a part in the delayed development.

The floating tree branch did an outstanding job of keeping the frog and salamander eggs from being exposed during times of falling water level.  A shortage of rainfall during March caused the pond water level to drop to record low levels for this time of year.  I was able to maneuver the tree branch into the deepest part of the pond and the eggs on the branch were spared exposure to the air.

Jelly masses that once protected salamander eggs broke lose and floated freely about the pond.

Almost all of the jellies were empty.  Most successfully produced salamander larvae, but a few contained unfertilized eggs that were consumed by fungus.

There were just a few larvae that had not left the egg.  Now I just have to wait a few weeks for the larvae to grow large enough for me to see them in the pond.  Water won’t be a problem for a while.  Thunder storms earlier today dropped 1.2 inches of rainfall and the pond is now near its full level.  More storm clouds are hurrying in from the west and I’m rushing to type this and get it posted before the heavy rain once again blocks my internet satellite link.

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