Mollusc Lab

Part 1 - Gastropods

There may or may not be living gastropods today.

Observe the tray of gastropod shells. You should be able to sort them into periwinkles, whelks, cone shells and limpets. Handle them for a few minutes; observe and comment on the difference between the top of the shell and the inside of the shell. Draw and label one representative of each type of gastropod.

Part 2 - Polyplacophora

There is a giant chiton on the tray. Observe and sketch. You may need to use the probe to scrape away tissue to reveal the plates. Count the plates. How many? Are they bendable? Try.

Part 3 - Bivalvia

Clam
There are three different types of live clams. Sketch each noting the difference. Obtain a clam and dissecting apparatus.  Carefully open, and try to find locate and identify the following organs/structures:  heart, 2 adductor muscles, intestines, stomach, gills, mantle. Make sure to use your dissecting scope! Examine and sketch also the differences between the interior and exterior shell. Notice the points of attachment of the adductor muscles. Observe the concentric growth lines on the shell representing growth. Want to try the smoked clams?

Mussel
Sketch one noting the difference between the interior and exterior shell. Obtain a mussel and dissecting apparatus.  Carefully open, and try to find locate and identify the following organs/structures:  heart, 2 adductor muscles, intestines, stomach, gills, mantle. Make sure to use your dissecting scope! Any byssal threads? Describe their texture.. Observe the concentric growth lines on the shell representing growth.

Oyster - Sketch one noting the difference between the interior and exterior shell. Obtain an oyster and dissecting apparatus.  Carefully open, and try to find locate and identify the following organs/structures:  heart, 2 adductor muscles, intestines, stomach, gills, mantle. Make sure to use your dissecting scope! Notice the points of attachment of the adductor muscles. Observe the concentric growth lines on the shell representing growth. Want to try the smoked oysters?

Scallop - Make a sketch of the exterior of the shell. Describe the texture of the raw scallop. How dioes it differ from what you would eat in an oyster or clam? Examine the bay scallops; what differences do you see?

Part 4 - Bivalvia

Squid
PROCEDURE:
Part I – External Anatomy:
1) Place the squid on the plastic plate dorsal side up (darker side). Notice the counter shading. One side is darker then the other.
2) Notice and label on the squid diagram the chromatophores. The “freckles” allow the squid to change colors. These spots change size to change the squid’s color for camouflage. Try rubbing them to see if you can see a change.
3) Look and label the fins. These help squid change direction when swimming.
4) Locate and label the mantle. The mantle is the main part of the squid’s body—all organs are inside.
5) Locate and label the pen. The squid is related to other “shelled” animals like clams and snails. The pen is all that is left of the shell the squids ancestors once had.
6) Look and label the eyes on the squid diagram. Squid have big eyes compared to their head. In comparison, humans’ eyes would be the size of dinner plates if the proportion were the same. They are positioned on the side. Being on the side gives them more peripheral vision, which is great for hunting.
7) Count and label the number of tentacles squid have. The tentacles are longer than the arms and have suction cups only at the tips. These are used to pass food to the shorter arms and then to the mouth.
8) Count and label the number of arms a squid have. Arms have suctions all the way down.
9) Hold your squid like a flower, let the arms lay back so you can see the mouth. You will be able to see the buccal bulb. The buccal bulb attaches to esophagus, which is attached to the stomach. Draw the buccal bulb in on the internal anatomy squid diagram and label it.
10) Look and try to find the beak. The beak is hard and is a dark brownish color.
11) Now, lay your squid ventral side up (lighter side). Locate the collar. The collar is the opening of the mantle (like the collar of your shirt).
12) Locate and label the siphon (a.k.a. funnel). Water is pulled into the mantle. Mantle is squeezed forcing water out through the siphon. This type of
movement is called jet propulsion. Squids are the fastest invertebrates swimming at approx. 30 mph.

Part II – Internal Anatomy
1) Place the squid on the ventral side (lighter side). Cut the mantle UPWARDS to avoid puncturing internal organs. Cut all the way to the tip of the tail. Lay the flaps of mantle to the sides.
2) Label and remove the gills from the body (place them on the side of the plate). The gills are feathery structures that absorb oxygen from the water.
3) Locate and label the inc sac. The inc sac lies on top of the liver. Carefully, pull it up with the tip of your scissors or finger and snip the inc sac away. Lay aside for now. The squid releases ink from this gland in times of danger, which is then pushed through the siphon.
4) Locate and label the heart. The heart is located at the bottom of the gills.
5) Locate the buccal bulb again. Try pulling on it gently to show the trail of the esophagus and general area of the stomach.
6) Locate and label the gonads. This is the reproductive organ. In males, it is a white-ish mound (sperm sac). In females, it is clear to yellow/orange mass of eggs.
7) Place your fingers on your mantle (on either side of the head). Peel back head and guts from the mantle. Locate and remove the pen.


Octopus
Observe an octopus. Does it have the same amount of tentacles as the squid?
Remove a sucker and sketch its appearance under a dissecting scope. Do the same for the beak.  Open up the body. What similarities and differences do you notice between the squid and the octopus? Can you locate the same anatomy using the same sketch for both? What is similar? What is different?
 

Checklist!!!!

have you included and labelled all sketches? They are highlighted in bold thruought the lab.
have you included the answers to all questions/observations? They are highlighted in italics thruout the lab.