Lab
Survey of Some Invertebrates
In this lab you will observe some examples of the invertebrates, those animals that do not
have a backbone. The hydras are in the phylum Cnidaria. TheDugesiaare in the phylum
Platyhelmenthes, the flatworms. The earthworm is in the phylum Annelida.
Materials:
- compound and dissecting microscopes
- slides and cover slips
- pipettes
- watch glass
- culture of living hydra
- Dugesia
- construction paper
- preserved earthworms
- dissection kits
Procedure:
- Hydra
(a) With a pipette, pull up some of the material from the bottom of the culture dish.
Thensqueezeacoupedropsontoacleanslideandcoverwithacoverslip. Observe
your hydra under the microscope and sketch one below. - Dugesia
(a) With a pipette, place a coupleDugesiaon a clean watch glass. Observe under
thedissecting microscope. Sketch below, labeling the eyespots, auricles, and
gastrovascular cavity.
(b)With a dark piece of paper, cover half the watch glass. Do theDugesiaseem to
prefer the shade or the light? Movement in response to light is calledphytotaxis. - Earthworm
(a) Find the clitellum. What is its function?
(b)Touch the ventral side of the worm to feel the setae. What are their function?
(c) Laythewormonthedissectingtraywiththedorsalsideup. Usingtheforcepsand
the scissors, carefully cut open the worm along a straight line from the clitellum
to the mouth. Make sure to just cut the skin so you do not damage the internal
organs. Sketch your worm below and label the following: aortic arches, crop,
gizzard, pharynx, dorsal blood vessel, intestine, ventral nerve cord, and seminal
vesicles.