Question

1.5 through which structure are male gametes released?
1.6 through which structure are females fertilized eggs released?
exercise 13 - 2
investigating locomotion in the vinegar eel
materials needed

• live vinegar eels (turbatrix aceti)
• culture medium
• test tubes with stoppers
• water baths at 10°c, 15°c, and 20°c
• dissecting microscope

like all invertebrates, roundworms are ectotherms, meaning they do not generate heat internally. the label “cold - blooded” is not an appropriate term for describing ectothermic organisms, because the body temperature of most birds and mammals (the traditional “warm - blooded” creatures) is well above that of most birds and mammals (the traditional “warm - blooded” creatures). ectothermic simply means that the source of body heat for an organism is outside the body. birds and mammals are endotherms, meaning that their body heat is generated from within.
it stands to reason, then, that an ectothermic animal such as a roundworm may be affected profoundly by changes in its surrounding environmental temperature. such changes may affect its behavior, metabolic rate, growth rate, and even its basic biochemical pathways. these features make ectothermic animals, such as the vinegar eel, turbatrix aceti, excellent models for elucidating the complex biological relationships between an animal and its thermal environment. vinegar eels are small, free - living nematodes that are harmless to humans and feed on a microbial culture called mother of vinegar used to create vinegar (hence their common name).
procedure
1 place a few vinegar eels (turbatrix aceti) into a clear test tube containing culture medium and insert the stopper.
2 using the dissecting microscope, observe their pattern of locomotion. how would you describe this pattern?
3 most nematodes display a characteristic undulating, whiplike pattern of movement. by focusing your attention on one small portion of the roundworms body (for example, the head or tail), you will be able to count the number of undulations over a given time frame. practice counting the number of undulations in your specimen over 30 - second time intervals. do this several times and record the number of undulations for each time interval.
time interval #1: ____________ (no. of undulations)
time interval #2: ____________ (no. of undulations)
time interval #3: ____________ (no. of undulations)
time interval #4: ____________ (no. of undulations)

Explanation:

1.5: In many organisms, male gametes (sperm) are released through the urethra in mammals or similar reproductive - related ducts in other species. But for the vinegar eel (a nematode), male gametes are released through the cloaca.
1.6: In female organisms, fertilized eggs are typically released through structures like the oviduct in vertebrates. For nematodes like the vinegar eel, fertilized eggs are released through the vulva.
For the locomotion part: By observing under the dissecting microscope, one can describe the undulating, whiplike pattern of movement of the vinegar eel. And then count the number of undulations in the given time - intervals as per the procedure.

Answer:

1.5: Cloaca
1.6: Vulva
For locomotion description: Undulating, whiplike pattern
For undulation counting: Fill in the number of undulations observed in each time - interval as per the actual observation.