The image above shows a squid dissection mount. Numbered structures shown on the mount include the funnel, or siphon, (1); anterior vena cava (2); funnel, or siphon retractor, muscle (3); intestine (4); ink sac (5); gills (6); branchial hearts (7); posterior vena cava (8); intestinal cecum (9); mantle (10) and the anus (11).

This image (and the accompanying close-up view) show a specially prepared squid dissection encased in a Lucite block. During the dissection, a midline incision was made and both sides of the circular mantle (1) were deflected to the side to reveal the internal organs. It is these rings of mantle in the intact squid that are eaten as calamari in many restaurants! The gills (2) and major arteries on this dissected squid have been injected with red latex, while the branchial hearts (3) that supply blood to the gills and major veins have been injected with blue latex. Note the large funnel, or siphon, (4) through which water is ejected to achieve a form of locomotion by "jet propulsion". A pair of lateral fins (5) helps provide stability during swimming. Squids have eight arms (6) that bear suckers along their length and two tentacles (7) that bear suckers (8) only on their distal ends. Except for a horny beak located inside the mouth (9), the squid has only a small vestige of an internal skeleton called a pen (10).

In terms of circulation, all cephalopods have a closed circulatory system. Blood is pumped to the body by a centrally located systemic heart (11). After delivering its oxygen to the squid's tissues, poorly oxygenated blood is returned to the gills via an anterior vena cava (12) and two posterior vena cavae (13) to be pumped to the gills (2) by a pair of accessory hearts called branchial hearts (3).

Squid are predators that capture prey with their arms (6) and tentacles (7) and dispatch the prey with a powerful beak (sometimes containing venom) inside of the mouth (9). Prey are detected with large eyes (14), the sides of one of which is seen on the dissection. From there, the food passes through the esophagus into the stomach to be digested. Once partially digested, the food is diverted to a blind pouch called the intestinal cecum (15) where the process is completed, after which the remaining wastes are discharged through the anus (16). Running along side the intestine is the ink sac (17), which can discharge a load of ink through the anus (15) that may help to conceal the squid's escape from potential predators or perhaps startle them into retreating. Also seen on this dissection of a male squid is the penis (18) through which sperm are inserted into the mantle cavity of the female during a head-to-head mating.

This image shows a number of anatomical features of a preserved, commercially prepared dissection mount of a freshwater mussel. Note the large, hatchet-shaped foot (1) that is used for burrowing into the substrate. The heart (5) has been injected with red latex, the gills (4) with blue latex and the intestine (9) with yellow latex. Digestive wastes are discharged from the intestine into the mantle cavity through the anus (10). Bivalves are distinguished from other molluscs by being having laterally compressed bodies encased in two shells (valves) that are held together by a dorsal hinge ligament (6) that causes the valves to open ventrally. The valves are drawn together by a pair of anterior (2) and posterior (8) adductor muscles, which are the parts of edible scallops that are eaten. In terms of nutrition, most bivalves are sedentary filter feeders. The posterior edges of the mantle (7) are modified to form a ventral incurrent siphon (11) that brings food and oxygen into the animal and a dorsal excurrent siphon (12) that takes carbon dioxide and wastes out.

The image above shows the inside of a freshwater mussel shell with all of its internal organs removed. Observe the iridescent lining of nacre (1). Near the anterior end of the valve is a raised portion called the umbo (2), which is the oldest part of the shell. The shells are held together dorsally by a spring like hinge ligament (3) that causes them to open. They are drawn together two muscles, the anterior adductor muscle (6) and the posterior adductor muscle (7). Grooves on the valves called hinge teeth allow the valves to securely interlock. In freshwater mussels there are two sets of hinge teeth, a posterior set of lateral hinge teeth (4) and an anterior set of cardinal hinge teeth (5).

The image above shows a preserved, dissected freshwater mussel. Note the conspicuous fold of tissue called the mantle (1). In molluscs the mantle is a sheath of skin that hangs down in two folds around the soft body and encloses a mantle cavity, which performs many of the same functions as a coelom in other animals. The outer side of the mantle secretes the shell while the inner side is ciliated, and along with gills (2), participates in gas exchange.

Note the prominent anterior adductor muscle (3) and posterior adductor muscle (4) that draw the two valves together to enclose and protect the animal from predators. The lateral hinge teeth (5) that help the valves to securely interlock can also be seen in this image. Observe the heart (6), which is contained within the pericardial cavity (7) located in a dorsal position just below the lateral hinge teeth (5). In molluscs, this cavity represents the remains of a much-reduced coelom. Note the conspicuous, hatchet-shaped foot (8) that is used for burrowing. In the image shown, a portion of the foot has been removed to reveal the greenish digestive gland (9) and gonad (10).

The image above shows another view of a freshwater mussel dissection. Structures that can be seen on this image include the lateral hinge teeth (3), cardinal hinge tooth (4), anterior adductor muscle (6), posterior adductor muscle (7), gills (8), the fleshy mantle (1), a portion of exposed nacre lining the shell (2) and part of the digestive gland (5) inside what remains of the foot (most of which has been removed during the dissection). Also visible on the above image is one of the two pairs of labial palps (9), flap-like structures attached to each side of the at the anterior end of the visceral mass near the anterior adductor muscle that help guide food particles toward the mouth.

http://www.uwlax.edu/Biology/Zoo-lab/Lab-6--Molluscs/

http://digital.lib.buffalo.edu/cdm/compoundobject/collection/BIO001/id/137/rec/7

http://www.usc.edu/org/cosee-west/Jun23-272008/SQUID_LAB_AnneMaben.pdf

1 The dorsal (top) side of the cuttlefish before dissection.

4. The open mantle cavity showing internal organs.

Beak

Cuttlebone

http://www.southernshores.net.au/beachcombing/archives/mayd02.htm

http://www.abccommercial.com/librarysales/sites/abccommercial.com.librarysales/files/studyguides/sg_cuttlefish.pdf

http://www.dps109.org/shepard/websites/dsmith/Lists/HomeworkAnnouncements%20for%20Students/Attachments/424/Squid%20Dissection%20-%20student%20version.pdf