Hidden Treasures Under Rotting Logs
Eight out of ten logs that I lifted up (and replaced in the position I found them) this week had tiny pearl-like eggs in clusters about one inch in diameter underneath them. Roughly 30 eggs were in each cluster. Whether these were slug or snail eggs I could not say, but mature slugs do deposit their eggs in the fall, often after mid-October, so one might assume these eggs were deposited by slugs. To see the hatching of slug eggs, which can take place in just a few weeks if conditions are right, go to https://www.youtube.com/watch?v=MsKtCZ99Hcw.
If a reader knows categorically how to distinguish snail from slug eggs, please enlighten those of us who are naturally curious with a comment!
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Land Snails Eating
While there are some terrestrial snails that are omnivorous and even carnivorous, most are herbivorous. Each species has a diet dependent on its size, age, habitat and individual nutritional requirements. They all must feed on foods that include significant amounts of calcium in order to keep their shell hard.
Those species that are herbivorous consume a variety of plants, including the leaves, stems, bark and fruits, as well as fungi and occasionally algae. They do so in an unusual way. Snails have an organ in their mouth with rows of tiny teeth, called a radula. When the food reaches this structure that looks like a sack, the teeth do not cut or grind it like human teeth would. Instead of being chewed, the radula scrapes the food and breaks it down before it passes through the esophagus to continue the digestion process.
The tiny teeth on the radula suffer much wear and tear as time passes. Therefore, they are continually replaced by others. Not all species have the same number of teeth. Some have rows with just a few teeth, while others have hundreds.
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A Gardener’s Favorite Beetle
Ground beetles (family Carabidae) are fast moving beetles, many of which are predators with specialized diets. One ground beetle (Cychrus caraboides) eats only snails (its head and thorax are very slender, allowing access to the inside of a snail’s shell). Another, Harpalus rufipes, limits its diet to strawberry seeds. Loricera pilicornis uses bristles on its antennae to trap springtails and mites.
The Bronze Carabid, Carabus nemoralis, (pictured) uses its large curved mandibles to crush and slice through prey – it will eat or try to eat just about any invertebrate, but specializes in capturing and eating slugs. Its hardened forewings, or elytra, have a coppery sheen to them, and parts of its thorax and the edges of its elytra are iridescent purple. This nocturnal, introduced, flightless, one-inch-long beetle resides throughout the Northeast and is already actively pursuing slugs.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
A Great Christmas Present!
If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill. A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!
One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”
In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”
I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!
Snail and Slug Eggs
Snails and slugs are very similar, except for a slug’s lack of a shell. Both are hermaphroditic, possessing male and female reproductive organs. In some species an individual may behave as a male for a while, then as a female. In a few species, self-fertilization occurs. Some species mate and lay eggs in the spring, some in the fall. Most snails and slugs that hatch in the spring can begin egg laying in the fall. The eggs of both snails and slugs are tiny, white or cream-colored, round and laid in roughly one-inch diameter clusters of 30 or so eggs. Look for these clusters under rotting logs, where they are protected from drying out as well as from freezing. (Remember to place the log back exactly as you found it.)
How Snails Feed
Most terrestrial snails are herbivorous, feeding on a wide range of vegetation. The snail’s mouth is on the bottom of its head near the shorter pair of tentacles. Snails (and all molluscs) consume their food not with mouthparts, like insects, or teeth, like mammals, but with a rasping tongue or radula. Snails don’t bite their food, but rather, rasp or scrape it. The radula is covered with rows of tiny “toothlets” which rasp particles away from vegetation and move them back towards the snail’s gullet. Different species of snails have differently-shaped toothlets. The radula is used by the snail not only to process food, but to clean bits of dried mucus from its shell. Supposedly if you listen hard, you can actually hear a rasping sound when the latter is occurring. (If you look hard, you can just barely see the orange radula of the land snail in the photograph.)
Naturally Curious wins National Outdoor Book Award
I am delighted to be able to tell you that this morning I learned that NATURALLY CURIOUS won the Nature Guidebook category of the 2011 National Outdoor Book Awards. I’m honored and humbled by this recognition. http://www.noba-web.org/books11.htm
Snails and Slugs
Snails and slugs are grouped together as gastropods – a class of Mollusks that includes land, freshwater and sea snails and slugs. The term “snail” is used for species with an external shell large enough for the soft parts to withdraw completely into it. Those gastropods without a shell, and those with only a very reduced or internal shell, are usually known as “slugs.” We refer to many marine gastropods as seashells, including whelks, conchs, cowries, olives, cone shells, figs and tulips. While many gastropods are herbivorous grazers, several groups are carnivores, capable of drilling through the skeleton of their prey.
Naturally Curious with Mary Holland 
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