These mainly aquatic types of carnivorous plants have their own special techniques for catching their meals. In fact, they are sometimes so effective that they catch tiny, just-hatched fish. We have at present several gallon containers in which we're working on just such a fish-catching study.
Unfortunately it is not completed so we can't guarantee how the project will conclude. Besides, we're just a bit more partial and friendly toward fish, having raised tropical fish for years. Insect-catching is one thing. Sacrificing poor baby fish seems a bit more difficult to do, but then again, many projects are needed in the interests of scientific advancement.
Since few firms offer bladderworts, you may find it necessary to trudge along the edges of bogs and roadside ditches looking for these floating carnivorous plants. The illustrations in the bladderwort chapter provide you with a good guide to the general appearance of the plants. They bear tiny yellow, bluish, or white flowers on slender stalks, depending on variety.
In New Jersey you can often see thousands floating happily on the water of flooded cranberry bogs. They are also quite common along roadside drainage ditches in the South.
These plants are sometimes also available through scientific supply companies such as NASCO in Ft. Atkinson, Wisconsin, and Stansi-Fisher of Clear Lake, Wisconsin. Schools, of course, have access to them through their usual science supply sources.
Materials—Aquarium or gallon jars, plants, hand lens.
Grow several bladderworts for a few weeks in the same aquatic conditions in which you find them in their native habitat. Then, as they begin to thrive, remove several and place them on blotting paper or paper towels.
Use the hand lens and, if you wish, a single-edge razor blade. Explore their flotation devices and the tiny bladders along the stems.
With the hand lens, try to spot the minute aquatic insects and larvae which have been sucked into the bladders and are in the process of being digested.
Materials—Bladderworts, containers, pond water.
Grow the plants by floating them in the aquarium or jars. Introduce several cups of pond or stream water. When you obtain it, try to scoop up some of the nearly microscopic swimming insects. Most ponds have a lively population wriggling and swimming about.
Then, keep a careful watch over a few weeks. If you have keen eyes, you'll eventually be able to spot activity and compare the plants as they begin their eating and grow more healthy, week by week.
With a microscope, you might also try some peeks into the water and at the bladders of the plants. Be careful and calm as you slice into the bladders and open up these tiny compartments for study. It takes a steady hand for such minute plants, but you'll find yourself looking into an amazing world that you probably never knew existed.
Materials—Bladderworts, containers, tiny fish.
Begin bv floating bladderworts in your aquarium. Then, introduce the tiny baby fish which you can scoop up with fine-mesh tropical fish nets from the edge of ponds in spring. We call them pinheads, since that's what they look like, just barely hatched and darting about. The most obvious characteristic is their head and eyes.
Hopefully, within about 10 weeks, you'll have some large bladderwort plants that have developed respectable-sized bladders. Keep a count of the fish. Note each day, since some may die and float to the top or drop to the bottom of the aquarium.
The reason to keep careful count is that you want to know when some pinheads are missing. From that point, begin the count of the bladders. Believe it or not, we and others have seen these tiny fish inside the bladders, sometimes with the tail tip still sticking out.
The sketch in the bladderwort chapter will show you what to look for in the typical ready-to-trap bladder, and one that had an aquatic mini-victim inside it.
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