animal is not feeding, the proboscis is retracted into a
cavity on the front of the animal. Pyrams typically live
out of sight during the day, under and around their chosen host. During the night they crawl up and find a place
where the mantle tissue is exposed adjacent to the shell.
They hang onto the shell and reach over to the mantle,
extending the proboscis to feed. Just inside the mouth is
a long, chitinous tube looking a bit like a very fine soda-straw and possessing a sharpened, delightfully pointed
tip. It functions rather like a fine-gauged intravenous
needle…perfect for drawing blood or other bodily fluid.
When it is time to dine, the proboscis extends out of
its specialized cavity in the front of the head and probes
around; the snail carefully selects a point on its host’s
skin where there are few, or no, nerve endings that register touch. In essence, it finds a place where the “donor”
literally feels no pain; this is typical of blood-suckers.
(Mosquitoes and vampire bats do much the same thing,
while leeches use an anesthetic to deaden the skin.) After
selecting its dining spot, the snail carefully stabs through
the skin and into a blood vessel or cavity below the epidermis to get its meal. These snails have muscular “bulbs”
in their bodies and actively pump out the donor’s blood.
After dinner, they presumably return to their refuge under the clam. Feeding has not been studied in any detail.
It is necessary for mosquitoes, vampire bats, leeches,
and, presumably, the nefarious Transylvanian Count to secrete anticoagulants into the wounds they make in
their ambulatory restaurants; good,
red vertebrate blood clots rapidly and
well. Such is not the case with the
blue or colorless molluscan blood; it
doesn’t clot at all. Instead, if a bleeding wound is formed in a snail or clam,
the body surface or the blood vessel
tends to squeeze the wound shut, and
the rapid growth of scar tissue permanently seals the hole. Once the snail
departs, the wound heals rapidly.
Depending on both the sucker and
the donor, blood may be either a complete or a quite incomplete meal. Female mosquitoes need extra protein to
produce their eggs, and they get that
from blood. Male mosquitoes may get
all of their nutritional requirements
from plant nectar, pollen, or sap, and
generally don’t suck blood at all. On
the other hand, vampire bats get all of
their nutrition from blood and, other than politicians, are the only true
mammalian parasites. Likewise, turbonillids apparently get all their nutrition from their victims.
Pyrams appear to be able to grow
rapidly on their diet of clam juice.
Once they reach sexual maturity, they
start to spawn. The single species that
has been studied was hermaphroditic.
Copulation resulted in internal fertilization and the deposition of shelled
eggs. With magnification, the eggs
may sometimes be seen within the
adult’s shell as tiny white dots. Development from fertilized egg to small
parasitic snail can be very rapid, and
within a week, the juvenile can be
dining next to its parent. Hobbyists