Snail Dissection

Step 1

  • Orient the specimen

Photograph of a freshly preserved animal. Note the head and tail region of the animal, as the specimen will appear different after removal of the shell. For humane purposes, ensure that the animal is completely unresponsive to touch before initiating the dissection. See supplies section on how to relax the specimen.

step01 Figure: 01

Step 2

  • Remove the animal from the shell

In some cases, it may be possible to remove the dead animal from its shell using curved forceps. If this is not possible, slowly break the shell from the aperture backwards, following the whorls, until the animal can be removed from the shell intact. (It is important to retain the broken pieces of the shell for identification purposes). A pair of needle-nose pliers may be used depending on the size of the animal’s shell.

step02 Figure:02

step03 Figure:03

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Step 3

  • Submerge “Shell-less” animal in 75% Ethanol or Water

Diagram showing a Helix species with the shell removed (Figure 06) was provided to assist with the orientation of the specimen. Place the “shell-less” adult specimen in a dish with 75% ethanol or water covering it.

step06 Figure 06 step07 Figure 07

Step 4

  • Uncoil snail and make an incision above the mantle skirt

Slowly uncoil the portion of the animal that was inside the shell to expose its contents. Make an incision just above the mantle skirt as indicated by the broken line in Figure 08. Be sure to make shallow incisions and angle the scissors upwards, and away from the internal organs. Cut as far along the skirt as possible.

step08 Figure: 08

step09 Figure: 09

Step 5

  • Cut along the length of the thin membrane

Cut along the broken lines as indicated in Figure 10. Avoid all internal organs/structures by only cutting the thin (transparent) membrane. Continue with the incision along the edge of the membrane all the way to the first whorl. This will expose portions of the reproductive and digestive system. Also, cut along the lines indicated in Figure 12 to expose the base of both systems.

step10 Figure: 10 step11 Figure: 11 step12 Figure: 12

Step 6

  • Peel back the membrane to expose the internal organs

Peel back the transparent membrane to expose the internal organs. Continue with the incision made in Figure 12 all the way to the end of the coiled regions of the animal (portion that was retained inside the shell).The animal may be inverted to accomplish this as indicated by the broken lines in Figure 15.

step13 Figure: 13 step14 Figure: 14 step15 Figure: 15

Step 7

  • Remove ovotestis from digestive gland

Slowly tease the ovotestis and the albumen gland away from the digestive gland. Both organs can be carefully separated with a pair of tweezers. Once dislodged, both systems can be separated as indicated in Figure 19.

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step17 Figure: 17

step18 Figure: 18

step19 Figure: 19

Step 8

  • Cut forward into the mantle skirt to expose the base of the reproductive system

Rotate the animal unto the side (may have to hold in hands) and cut into the mantle skirt going forward, towards the head. Be sure to make the incision between the ocular tentacles. This cut will expose the basal region of the reproductive system.

The pins can be removed from the specimen for photography or closer examination.

step20 Figure: 20

step21 Figure: 21

Step 9

  • Detach the reproductive system

Gently separate the reproductive system from the digestive system. Note the genital opening in Figure 22. Make incisions along the broken lines as indicated in Figure 22. Be careful to avoid cutting through the atrium. This incision will detach the entire reproductive system form the rest of the animal (Figure 23). Use an insect pin to gently unravel the vas deferens, bursa copulatrix, oviduct, flagellum, and penis by following the connection to each.

step22 Figure: 22

step23 Figure: 23

Step 10

  • Treatment for Photography

If a photograph of the reproductive system is required, the structures can be arranged and pinned as desired then fixed in place by immersion in 95% ethanol for approximately 15 minutes. DO NOT leave the reproductive structures in 95% ethanol for an extended period as dehydration and distortion will occur. The pins can be removed from the specimen for photography or closer examination.

step24 Figure: 24

step25 Figure: 25