Behavior of Microorganisms
Hydra, Planaria, Paramecium
Dissecting Scope
Usually 10X eyepiece
Usually 2X to 4x objective
Illumination System:
• Usually lights switches can turn lights to shine above or below the specimen
Illumination
• Transmitted light from below through thin specimen (like a fly wing)
• Reflected light from above for opaque objects (like a penny)
Dissecting scope
• Does not invert the object
• Does not have to be transparent or translucent
e
Letter “e” appears the same as how you put it under the lens
What happens?
• Move the ‘e’ to the right…it looks like it is going to the right as you look through the lens…
• There is no inversion.
•e
Look at colored print
• What did you see when you put colored newspaper print under the lens?
• ANSWER: A lot of colored dots
Hydra viridis
Two layers of cells which make up the body of a Hydra polypThe outer clear layer (the ectoderm) is the one which contains the nematocysts, or stinging cells.
Contracted, the hydra looks like a tiny cactus. Its colorcomes from symbiotic algae living in the hydra's tissues.
Hydra StretchedFully extended, its tentacles sweeping the water for its prey, the hydra reaches a height up to two inches.
Hydra Bud Snares a Cyclops with its
tentacles, a hydra bud snares a Cyclops, a tiny,
one-eyed crustacean, also named after an
ancient Greek monster. The bell-shaped
protrusion on the hydra's body (upper left) is a second hydra bud.
Tentacles curled, a hydra is
ingesting its prey. Its mouth is
at right.
• The hydra is at rest, digesting its meal.
A mature bud has extended itself into a long stalk and is about to pinch itself off and depart.
Good Luck, Little Buddy!
• One hydra bud somersaults away from its parent as another grows. Hydras often have four buds at a time.
Is it worth it?
• When autumn arrives, bringing conditions that threaten the survival of the hydra, it ceases to replace itself and goes
sexual. For the hydra, the price of sex is usually death!
• In the image shown right you will see the male organs just behind the arms; the female organ, much larger, is situated a bit lower on the animal.
• In the image shown right the sperm is oozing out of the male organ, in the image shown below a ripe egg is visible.
• The egg is coming from the parent.
Nerve Net
• Hydra have a simple nerve-net which connects with the stinging cells in the tentacles.
Earthworm
• . Cephalization – has a brain (that co-ordinates the information coming into it from the sensory cells. It then sends information to the muscle cells and other tissues through a network of nerve cells.)
Hydra
• Drawing #3 - Put a living Hydra in a drop of water on a depression slide. If there are no living Hydra available use a longitudinal section ( l.s.) slide. Hydra only display the polyp body form.
• Planarians are hermaphroditic, that is, they contain both male and female sex organs. They can reproduce asexually simply by pinching in half; each half grows a new half.
Planaria
• Movement is accomplished by the use of cilia and also by muscular contractions.
VIDEO - Planarian movment (Dugesia) (1.83 MB)
• Drawing #4 - Whole mount of discharged nematocysts (stinging structure found within cnidocytes). You must use high power (450X) to see these.