Reproduction of the Edible Snail (Helix pomatia)

Like most gastropods, Helix pomatia is hermaphroditic - that is, they have the reproductive organs of both genders. They still engage in sexual reproduction, and the mating rituals of some land snails are truly bizarre.

When two sexually mature snails meet and determine that they’re going to mate, “love darts” will often be exchanged in a pre-mating ritual. However, these darts are not part of the insemination process; mating takes place after this exchange.

Darts don’t always hit their target (the other snail), and snails don’t always go into this “battle” with a dart prepared - snails who have never mated previously cannot create a dart, as the dart sac is not yet primed to lay down the chitin that the darts are comprised of. However, a snail who manages to hit their mate with a dart prior to mating have been shown to cause their mate to create a significantly higher number of eggs, and of those eggs, a higher percentage successfully hatch.

The Naturalists Miscellany. George Shaw, 1790.

dendroica:

n340_w1150 by BioDivLibrary on Flickr.

Via Flickr:
Voyage dans l’Amérique Méridionale. v.9.
Paris :Pitois-Levrault,1835-47.
biodiversitylibrary.org/item/50740

rhamphotheca:

Blascka Glass, The Harvard Collection

Museum workers clean a glass sculpture of the nudibranch, Casella philippinensis, by Leopold Blaschka, at the Museum of Comparative Zoology at Harvard University.

“… For decades, the MCZ’s Blaschka glass invertebrates were stored in the relevant departmental collection by taxa, as their primary and original use was for teaching and morphological comparison. Around 1900, the glass invertebrates were removed from their original cardboard trays and mounted with wire to white plaster plates, as they remain today.

The models have recently been recurated as a cohesive collection in the MCZ, and a major initiative is currently underway to clean and repair all of the models. Most of the damage to the models is minor and due to the failure of the original 19th century glue used in their construction. Faulty contact points are restored with reversible, archival adhesive…”

(photo/read more: MCZ - Harvard)

An interesting tale of natural history being restored…and it’s the natural history of the coolest invertebrates out there.

Radiograph of Nautilus Shell

Though it’s not a perfect golden spiral, the chambered nautilus shells (of both the extant and extinct species) are some of the finest natural examples of a logarithmic spiral.

Build thee more stately mansions, O my soul,

As the swift seasons roll!

Leave thy low-vaulted past!

Let each new temple, nobler than the last,

Shut thee from heaven with a dome more vast,

Till thou at length art free,

Leaving thine outgrown shell by life’s unresting sea!

- Oliver Wendell Holmes

On Growth and Form. D’Arcy Wentworth Thompson, 1945

Land Snail Shells

Did you know that the science of studying gastropod shells is called conchology? Almost 90% of gastropod shells coil to the right. Oh, oh, and the color “Tyrian purple” (the purple that only emperors and royalty were allowed to - or could afford to - wear) comes from the Spiny dye-murex shell!

Shells are cool!

 Conchylien-Cabinet Lüneburg. Nicolaus Georg Gevens, 1830

New Land Shells from Taviuni [Taveuni] - Click through to greatly enlarge these teeny guys!

These little snails are from the third-largest Figian island, Tavenui. Tavenui is one of the best-preserved islands of the Fiji archipelago, as the population is almost entirely indigenous populations (living a simple sustenance lifestyle), and foreign predators like the mongoose have never gotten a foothold. Luckily, as the business of ecotourism continues to expand, the incentive to keep the island (and its native flora & fauna) intact. The rich volcanic soil that comprises the island would otherwise likely be exploited for palm oil and coconut production.

I’ll take awesome teeny snails, unique fruit bats, orange doves, and Kula parrots over a few tons of palm oil any day.

From Proceedings of the Scientific Meetings of the Zoological Society of London for the year 1876.

Life Cycle of Liver Fluke

The life cycle of the fluke that causes schistosomiasis has a very similar life cycle, except where the liver fluke enters and matures within the sheep liver, the schistosome enters the human skin, and matures within the mesenteric veins, though they can easily move between tissues and locations.

Animal Parasites and Human Disease. Asa C. Chandler, 1918.

Common Limpet

These limpets have a cool way to eat algae off of rocks - their scraping radula (a rasp-like structure) is reinforced with iron and other minerals.

The limpets on this card are marine gastropods. They absorb oxygen from the water, using gills. Freshwater limpets are actually fairly unrelated to marine limpets; though they have the same shape (which is why they’re called “limpets”), they breathe using a lung structure, and developed their form separately from their distant marine cousins. Comparing the two gives a great example of convergent evolution.

Wisconsin Historical Society Archives. Hignett’s Cigarette Co. Ca. 1910-1915.