Photo of the day (90): Lymnaea stagnalis

Lymnaea stagnalis is a species of a common holarctic freshwater snail from the family Lymnaeidae. It usually inhabits standing waters and also temporary pools. What will happen to Lymnaea stagnalis snails when is the temporary pool out of water?

This is a temporary pool in the southern part of the Litovelské Pomoraví Protected Landscape Area, Czech Republic at June 29, 2018.Fortunately Lymnaea stagnalis can survive outside water for some time. Most of them were still alive.

There are also some Stagnicola turricula snails (those smaller ones) among Lymnaea stagnalis. It is also species from the family Lymnaeidae.References

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2018 exhibition of molluscs of Vysočina Region in Museum of Highlands

There is an exhibition of molluscs of Vysočina Region in Jihlava. The exhibition is held in Museum of Highlands (Muzeum Vysočiny Jihlava) in Jihlava from April 27 to June 10.

The exhibition is quite unique, because it focus on local malacofauna of the Vysočina region. No other exhibition about non-marine molluscs of the Czech Republic or of its part was held yet.

I thank to Pavel Bezděčka, the curator, who provided following photos of the exhibition.

Exhibition of molluscs of Vysočina Region. Photo by Pavel Bezděčka, CC-By-4.0.

Shells of various freshwater snails. Photo by Pavel Bezděčka, CC-By-4.0.

Shells of freshwater snails. Photo by Pavel Bezděčka, CC-By-4.0.

Shells of land snails. Photo by Pavel Bezděčka, CC-By-4.0.

Shells of various small species of land snails. Photo by Pavel Bezděčka, CC-By-4.0.

Helix thessalica, Helix pomatia and Cepaea hortensis shells. Photo by Pavel Bezděčka, CC-By-4.0.

Sinistral and normal dextral shell of Helix pomatia. Normal dextral and sinistral Cepaea hortensis. Photo by Pavel Bezděčka, CC-By-4.0.

Examples of historical publications of molluscs of Vysočina Region are represented mainly by works by Hans Canon. Photo by Pavel Bezděčka, CC-By-4.0.

Examples of recent research publications about molluscs of Vysočina Region. Photo by Pavel Bezděčka, CC-By-4.0.

One of 14 panels at the exhibition. Photo by Pavel Bezděčka, CC-By-4.0.

Information panels and shells of freshwater snails. Photo by Pavel Bezděčka, CC-By-4.0.

Slugs are on photos only. Photo by Pavel Bezděčka, CC-By-4.0.

There is also an aquarium with live gastropods. Photo by Pavel Bezděčka, CC-By-4.0.

There are also shells of bivalves Photo by Pavel Bezděčka, CC-By-4.0.

Shells of bivalves. Photo by Pavel Bezděčka, CC-By-4.0.

Exhibition of molluscs of Vysočina Region. Photo by Pavel Bezděčka, CC-By-4.0.

Shells of bivalves. Photo by Pavel Bezděčka, CC-By-4.0.

References

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Photo of the day (66): Pila ampullacea

Pila ampullacea is a freshwater snail originally from the Southeast Asia. It belongs to the family Ampullariidae.

These snails are edible and they are regularly collected and consumed in Vietnam in various ways. They should be parboiled, because raw or undercooked snails can transfer parasites such as metacercariae of Echinostoma causing echinostomiasis.

I thank my friend Jan Vrba who kindly provided the photo.

A dish of Pila ampullacea from Ho Chi Minh City, Vietnam. Photo by Jan Vrba, CC-BY-4.0.

This food was served in a restaurant under the Vietnamese name “Ốc hầm thuốc bắc”, that means approximately something like “Slowly cooked snails, (recipe from) northern (traditional) medicine”. It is just a name for attracting customers. I think, they should write word cuisine instead of medicine. However snails are important source of proteins, especially in areas where proteins are scarce.

References

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Photo of the day (57): Daudebardia rufa

Daudebardia rufa is a carnivorous semi-slug. It belong to the subfamily Daudebardiinae within the family Oxychilidae or it can be classified in a separate family Daudebardiidae.

They are uncommon, because they can not live in highly altered forest monocultures. They require sufficiently humid forests with enough leaf litter, logs and fallen wood. There should be enough prey such as earthworms and snails. Humid habitat is necessary, because they have no shell large enough to protect them against droughts. My Daudebardia rufa comes from Moravia, the Czech Republic.

The right side view looks like this. The large muscular body has some tubercles. There is visible a pneumostome (breathing pore) bellow the shell. The body length of this specimen is 17 mm.
The shell looks like this:
References

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Photo of the day (54): eggs of Ancylus fluviatilis

Adults of freshwater gastropod Ancylus fluviatilis have a cap-like shell. But shells of its embryos are a bit different. You can find eggs of Ancylus fluviatilis in spring and in early summer on stones in streams. I found these eggs in northern Bohemia in June.

Eggs are laid in capsules. There are 9-12 eggs in each capsule.

There can be seen foot, eyes and tentacles under stereo microscope easily in this state of development. There are also ribs on the shell, that resemble ribs of some Patella species to me. I have taken the photo in situ.

I found no images of eggs of Ancylus fluviatilis for comparison on the internet after a brief search.

References

Species summary for Ancylus fluviatilis. AnimalBase, last change 26 October 2013, accessed 8 July 2016.

Streit B. (1976). Energy flow in four different field populations of Ancylus fluviatilis (Gastropoda-Basommatophora). Oecologia, 22(3): 261-273.

Embryonic development of Bithynia tentaculata

Bithynia tentaculata is a well known freshwater snail from the family Bithyniidae. It occurs in the Palearctic. Females lay eggs and the development lasts few weeks depending on the water temperature. It hatch after 12-14 days at the temperature 25 °C (Cather & Verdonk 1974). I had temperature 26 °C in my aquarium, so my snails hatched out in the 12th day.

This is how they look like shortly before hatching:

Eggs are usually laid in two rows. There is seen a bit compressed shape of eggs, when you will look out from the side view:

It will go though the cleavage, blastula, gastrula in the first two days. This very early development was studied by various scientists (Erlanger 1892, Van Dam 1986).

Day 1:

Day 2:

Day 3:

Then it will form a radula, shell, nervous system, tentacles, ctenidium, heart, foot, snout and other organs. The shell is translucent, so if you would watch the embryo in the microscope, then there would be ctenidium and heart easily recognisable.

Day 4:

Day 5:

Day 6:

Day 7:

There is clearly visible a shell by naked eye since the seventh day.

Day 8:

Eyes, foot, head and snout are clearly recognizable.

Day 9:

Day 10:

Tentacles are visible easily.

Day 11:

Day 12 – hatching:

The first hatched snails:

The diameter of hatching snails is 1.2 mm and their weight is 0.25 mg (Negus 1998).

Day 13:

There left only empty egg cases and incorrectly developed embryos in the 13th day.

So this is a brief insight how Bithynia tentaculata develops and how you can see it by naked eye or by magnifying lens. But it is a worth to use microscope.

When it will be lucky and if no predator will eat the juvenile snail, it will grow into a snail like this:

References

Cather J. N. & Verdonk N. H. (1974). “The development of Bithynia tentaculata (Prosobranchia, Gastropoda) after removal of the polar lobe“. Journal of embryology and experimental morphology, 31(2): 415-422.

Erlanger R. (1892). “Beiträge zur Entwicklungsgeschichte der Gastropoden”. Mittheilungen aus der Zoologischen Station zu Neapel 10: 376-404.  Plate 25-26.

Negus M. R. (1998). “A Life Table for the fresh water mollusc Bithynia tentaculata (L.)”. Journal of Biological Education, 32(1): 14-23, DOI:
10.1080/00219266.1998.9655588 abstract

Van Dam W. I. (1986). “Embryonic development of Bithynia tentaculata L. (Prosobranchia, Gastropoda). I. Cleavage”. Journal of Morphology 188(3): 289-302. DOI: 10.1002/jmor.1051880304 abstract

Photo of the day (47): Lithoglyphus naticoides

Lithoglyphus naticoides is a freshwater snail. Its distribution is Pontic and Danubian.

Shells from my collection comes from Danube river in Slovakia. The apertural view of the shell looks like this. The width of the shell is 8.5 mm and the height of the shell is 8.5 mm:

Oblique view of the same shell:

It lives on the muddy bottom, and it can not lay egg capsules on stones. Therefore is lay egg capsules on shells of other Lithoglyphus naticoides snails. Remains of egg capsules on the shell of Lithoglyphus naticoides:

Dried egg capsules that have a dried embryo inside:

The width of the following shell is 7.0 mm and the height of the shell is 7.0 mm.

I wanted to see a color photo of an operculum of Lithoglyphus naticoides, but I found color drawings on the internet only and black-and-white photo of an operculum in books. So I made few photos of an operculum of Lithoglyphus naticoides.

The width of the operculum is 3.0 mm and the height of the operculum is 4.0 mm. It is the operculum from the shell above. Outer side of the operculum:

Inner side of the operculum:

References

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Photo of the day (45): water mite on a Helisoma anceps

Water mites is a group of about 5000 species of mites. Scientific name of them is Hydrachnidia or Hydrachnidia or Hydracarina or Hydrachnellae. They are usually very small and this is one of them. I found it in my freshwater aquarium on Helisoma anceps. It is so small that I had to use lens to verify, that the small dot on the shell is a water mite. The water mite is in the centre of the photo. It is on the mantle edge near the aperture. Detail cropped from the previous photo: You can compare the size of the water mite with two Ferrissia fragilis snails on the top of the shell of Helisoma anceps. Both of these freshwater snail species are of North American origin and both belong to the same family Planorbidae. Ferrisia fragilis can reach 3.2 mm maximum shell length, but I think my snails are a bit smaller. The water mite is about 0.5 mm or smaller. It was actively moving on the snail. The dot in the centre of the photo is the water mite: I do not know the origin of the water mite. I found only one in my aquarium meantime.

Photo of the day (44): eggs of Helisoma anceps

Helisoma anceps lays eggs in gelatinous translucent clusters.

This cluster is taken shortly after eggs laying. I think it is about the second or the third day. There are seen five small dot-like embryos:

Another cluster of eggs contains six more developed embryos:

This is yet another cluster of nine eggs shortly before hatching. Eight hours later all snail were hatched. The length of this whole cluster is 4 mm and it is attached to a stem of a common freshwater plant from the genus Hydrocotyle. There are seen shells of all nine embryos and there are seen heads with eyes of three snails in the first row:

Photo of the day (42): Bithynia transsilvanica

Bithynia transsilvanica is an eastern European freshwater snail. This species was previously known as Bithynia troschelii.

Frontal view:

It is very similar to Bithynia leachii. But Bithynia transsilvanica is larger and it can reach up to 11 mm in shell height. The first three photos are of the same specimen and the width of the shell is 8 mm and the height of the shell is 10 mm.

Lateral view:

View of a foot:

Another photo is of a smaller Bithynia transsilvanica snail. The width of the shell is 7 mm and the height of the shell is 9 mm. There is seen its operculum, that is slightly pointed. It is an important identification feature:

References

Beran L. & Horsák M. (2009) “Distribution of Bithynia leachii (Sheppard, 1823) and Bithynia troschelii (Paasch, 1842) (Gastropoda: Bithyniidae) in the Czech Republic“. Malacologica Bohemoslovaca 8: 19-23.

Horsák M., Juřičková L. & Picka J. (2013) Měkkýši České a Slovenské republiky. Molluscs of the Czech and Slovak Republics. Kabourek, Zlín, 264 pp. (in Czech and English). pages 29 and 43.