Biology and ecology

Cross-fertilization

Terrestrial gastropods have the ability to independently manipulate the movement of the eggs and sperm that originate in the ovotestis.

1. Sperm cells are continuously produced by the ovotestis and released into the hermaphroditicHermaphroditic:
   State of having both male and female reproductive organs. (See also Hermaphrodite)
   duct. The sperm cells may be temporarily stored in the hermaphroditicHermaphroditic:
   State of having both male and female reproductive organs. (See also Hermaphrodite)
   duct in seminal vesicles. When the sperm cells are needed for fertilization, the sperm cells actively migrate from the hermaphroditicHermaphroditic:
   State of having both male and female reproductive organs. (See also Hermaphrodite)
   duct to the fertilization pocket. Inside the fertilization pocket is a structure called the sperm duct. The sperm duct forms a grooveGroove:
   An elongate and fairly uniform depression or indentation in the shell or soft parts of a mollusc.
   that can be voluntarily closed by the animal during copulation. This functions to prevent self-fertilizationSelf-fertilization:
   This is an event where an organism is produced by the fertilization of an egg by sperm from the same organism. (See also hermaphrodite)
   when not desired.
2. The sperm then migrates to the prostate gland, which produces fluids that provide nourishment to the passing sperm cells. This fluid is very thick and immobilizes the sperm cells. The immobilized sperm cells are then transported towards the vas deferens by the peristaltic movement of the walls of the prostate gland.
3. The sperm cells are then transferred from the vas deferens to the penis via the epiphallus. The penis is then everted and the sperm mass deposited into the recipient’s atriumAtrium:
   Opening or passage of the genitalia. OR Region for the reception of gametes.
   .
4. The sperm cells may be transferred directly into the mating partner’s bursa copulatrix.
5. A small percentage of the sperm cells deposited into the bursa copulatrix will migrate into the oviduct.
6. The sperm cells now migrate from the oviduct into the fertilization pouch-spermatheca complex.
7. Eggs are voluntarily released from the ovotestis into the fertilization pouch-spermatheca complex where it will unite with sperms that have migrated there.
8. The fertilized eggs (zygotes) are provided with a nutritious albumen coat that is produced by the albumen gland. The eggs are then transported from the fertilization pouch-spermatheca complex into the oviduct section of the common duct where they may be arranged in a line (resembling a pearl necklace). Several layers of material of rich in calcium are then deposited around each egg prior to being laid by the recipient.
9. The recipient animal then deposits the fertilized eggs.

It should be noted that self-fertilizationSelf-fertilization:
This is an event where an organism is produced by the fertilization of an egg by sperm from the same organism. (See also hermaphrodite)
could occur in a similar manner as described above, except no donor is involved.