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.