Lab #2: Mussels

Question 1

Scientific name, phylum, and class for Blue Mussels

Answer 1

Mytilus Edulis

Phylum = Mollusca
Class = Bivalvia

Question 2

What are bivalves?

Answer 2

= organisms possessing two valves or shells

Question 3

What and how (the major process) do mussels feed?

Answer 3

–> They eat plankton

–> SUSPENSION FEEDING

Question 4

Pathway of plankton ingestion and excretion by mussels

Answer 4

1. Inhalant siphon
2. Ctenidia
3. Labial Palps = SORTING

4A. Components sorted as NON-food released as pseudofeces through the INHALANT SIPHON

4B. Components sorted as food = go to mouth
5. GI tract
6. Anus
7. Exhalant siphon

Question 5

What are ctenidia?

Answer 5

Ctenidia are comb-like or feather-like gills

–> Respiratory organs that also play a role in filtering ingested food

Question 6

What is the organization of ctenidia?

Answer 6

The ctenidia are divided into two demibranches that are connected by ciliated filaments

Question 7

What is the direction of flow in the ctenidia?

Answer 7

Ingested food moves from the posterior (siphon end) to anterior (mouth end) end through the demibranches and filaments

–> Some particles may move from dorsal to ventral (top to bottom) through the filaments to the opposite demibranch and then continue in the anterior to posterior direction

THEN the food that is sorted in the labial palps as NOT FOOD (pseudofeces) gets sent ANTERIOR to POSTERIOR to be released at the inhalant siphon

Question 8

Answer 8

A = Inhalant Siphon
B = Ctenidia
C = Bysuss
D = Foot
E = Inner Labial Palp
F = Anterior Adductor Muscle
G = Mouth
H = Outer Labial Palp
I = Posterior Adductor Muscle
J = Anus
K = Exhalant Siphon

Question 9

Denote the anterior, posterior, dorsal, and ventral ends of the mussel

Answer 9

Note: To remember dorsal vs ventral, think of a DORSAL FIN = on the back of whales, therefore dorsal refers to the spinal area!

Question 10

What are the byssal threads for in mussels?

Answer 10

To aid in attaching to rocks

Question 11

What is a standard curve?

Answer 11

A graph that depicts the relationship between the concentration of a known substance and its measured response

–> The slope of this graph can be then used to determine the concentration of an unknown sample using its measured response

Question 12

What was the standard curve for the mussel filter feeding experiment?

Answer 12

X-Axis = Concentration (of known samples)

Y-Axis = Absorbance of the known conc. sample

Question 13

How to create a standard curve:

Answer 13

1. Plot the points for the different known conc. samples and their observed response (Ex: absorbance)
2. Add a line of best fit to the points (make sure R2 is high)
3. Use the line equation from the standard curve to determine unknown conc. from measured response

Question 14

How did we use standard curve to determine unknown conc. of algae in solution? Show calculations

Answer 14

The standard curve line equation (y=mx+b) could be used to determine the unknown conc.

B (y-int) we set to ZERO

Y = absorbance and X = conc.
M = slope of line of best fit

–> We want to plug in Y from the unknown conc sample, using the M value from the standard curve and SOLVE FOR X

Question 15

As time went on, did the absorbance of the algae solution increase or decrease?

What did this signify?

Answer 15

The absorbance of the solution DECREASED over time as the solution was becoming more cleared of particles = less substances in the solution to absorb the light

–> Signified that the mussels were filter feeding successfully! (water was becoming motr coear)

Question 16

What is a serial dilution?

Answer 16

A serial dilution is a step-wise series of dilutions, where the dilution factor stays the same for each step

–> Ex: Dilute a solution 4x and then dilute that diluted solution 4x to get a 16x dilution and then dilute that dilution 4x to get a 64x dilution…

Question 17

What pieces of info are needed in order to conduct a serial dilution?

Answer 17

1. Concentration of stock solution (non-diluted/reference soln.)
2. Dilution factor
3. Required FINAL VOLUME

Question 18

What is the transfer volume in serial dilutions?

Answer 18

How much of the stock solution must be added to the diluent to create the wanted dilution

AND then how much of each diluted solution needs to be added to diluent in order to generate subsequent dilutions

the amount of sample you physically transfer to create the next dilution step

Question 19

What is the diluent in serial dilutions?

Answer 19

The substance that a given concentrated sample is being diluted into

Question 20

How do you calculate transfer volume for serial dilution?

Answer 20

(Desired Final Vol. / Dilution Factor) = Transfer vol.

Question 21

How to determine the amount of diluent to add to each tube in a serial dilution?

Answer 21

Diluent vol. = (Desired final vol.) - (Transfer vol.)

Question 22

How can you determine concentration of a given dilution in a serial dilution?

Answer 22

Divide the initial concentration (of the undiluted sample) by the dilution factor for the given dilution you want to calculate the concentration for

Question 23

Serial dilutions are _________

Answer 23

Exponential

–> Each subsequent dilution is just the previous dilution times the dilution factor

Ex:
1st dilution = 4x
2nd dilution = 4 x 4 = 16x
3rd dilution = 4 x 4 x 4 = 64x
4th dilution = 4 x 4 x 4 x 4 = 256x
ETC..

Question 24

How to balance centrifuge with trio of tubes vs a pair of tubes

Answer 24

Trio of tubes = FORM TRIANGLE (7 spaces between each tube)

Pair of tubes = PLACE EQUIDISTANT (11 spaces between the tubes)