I didn’t have too much homework yet, and it was a nice day,
so I decided to spend the afternoon reading a book in Humboldt park. I found a
nice spot next to the lagoon on one of those little stone fishing spots that
allow you access to the water. I had not been to Humbolt Park before, and most
of what I had heard about it gave it an unsavory reputation, so the small
community of wildlife that I found surrounding the lagoon was a pleasant
surprise. Dragonflies of many shapes and colors flew around the grass snatching
up insects, and I could hear frogs singing in the reeds. There were birds,
fish, and most surprising, 5 or 6 massive freshwater snails.
.JPG) |
| The snail I found in Humboldt Park |
The largest of these snails was the same length as my palm
is wide, with a ‘foot’ about an inch in diameter. The shell was dark greenish
brown, but appeared to be covered in algae, so the original, algea-less color
of the shell was hard to identify. The foot of the snail was hard, and appeared
to have grown out concentrically, like the rings of a tree. When the snail
closed itself by raising it’s ‘trap door foot’ it was surrounded on all sides
by an in-penetrable shell. I sang to it for a while, and after about 20 minutes
it came far enough out of it’s shell for me to see that it’s flesh was
yellowish brown in color, with two long tentacles.
Internet research has led me to identify this snail as a
Trap Door Snail, or Chinese Mystery Snail. Trapdoor snails are freshwater
mollusks of the viviparidae family,
which lack a lung and have no need to breathe air. Because of this they
can survive in cold climates were the surface of the water freezes over in the
winter. Snails in this family also give birth to live young instead of laying
eggs.
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| Many Species of Viviparidea |
It seems that Trap Door Snails are often used in ponds and
aquariums to control algae growth. These snails eat algae like it’s their job,
but leave live plants alone. Thus, they are introduced into many aquariums
(along with other snail species, such as the apple snail) as tiny aquatic
lawnmowers. Trapdoor snails are a popular choice for this in the Northern
United States because of their ability to survive the winter. I was curious as
to if I could identify this snail past family, and I have tentatively settled
on Bellamya japonica, the Japanese
Mystery Snail, also known as the Japanese Black Snail, or Japanese Trap Door
Snail. As the name suggests, these snails were originally only found in the
lakes and rivers of Japan. After being introduced to the United States they
have spread to inhabit most of the Northern United States, and are very common
around the great lakes. Unlike most invasive species though, I have found
little documentation of ill effect caused by these Japanese Trap Door Snails.
 |
| Shell of Japanese Mystery Snail. Looks like mine, right? |
It is possible that the Parks District of Chicago placed
these snails in Humbolt Park on purpose, to control the growth of algae in the
lagoon. I found many websites marketing these snails to owners of pond’s an
aquariums as algae control, and it would make sense that a stagnant pond in a
city park would need something to keep it’s algae levels down. However it is also possible that these snails
arrived in Humbolt Park naturally, found the snail’s idea of an all-you-can-eat-buffet,
and decided to stay, reproduce, and grow to a monstrous size.
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| Range of the Japanese Mystery Snail |
I was also curious as to if singing to snails in order to
lure them out of their shells really worked, or if that is just a romantic idea
I chose to believe on the Maine beaches of my childhood. I looked up but I
couldn’t find any reliable information online, does anyone know the answer? Is
it the vibrations? Is it just that singing gives you something to do while you
hold still long enough for the snail to think it’s safe. Do snails really come
out of their shells when sung or hummed to?
-IR
http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=1046
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