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.
Daudebardia rufaThe shell looks like this:
Daudebardia rufaReferences

no references

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.

egg capsules of Ancylus fluviatilisThere 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.

eggs of Ancylus fluvitilisI 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:

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

Bithynia tentaculataIt 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:

Bithynia tentaculata

Day 2:

Bithynia tentaculata

Day 3:

Bithynia tentaculata

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:

Bithynia tentaculata

Day 5:

Bithynia tentaculata

Day 6:

Bithynia tentaculata

Day 7:

Bithynia tentaculata

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

Day 8:

Bithynia tentaculata

Eyes, foot, head and snout are clearly recognizable.

Day 9:

Bithynia tentaculata

Day 10:

Bithynia tentaculata

Tentacles are visible easily.

Day 11:

Bithynia tentaculata

Day 12 – hatching:

Bithynia tentaculata

The first hatched snails:

Bithynia tentaculata

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

Day 13:

Bithynia tentaculataThere 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:

Bithynia tentaculataReferences

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:

shell of Lithoglyphus naticoidesOblique view of the same shell:

an oblique view of the shell of Lithoglyphus naticoidesIt 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:

the shell of Lithoglyphus naticoides with egg capsulesthe shell of Lithoglyphus naticoides with egg capsulesDried egg capsules that have a dried embryo inside:

the shell of Lithoglyphus naticoides with egg capsulesthe shell of Lithoglyphus naticoides with egg capsulesthe shell of Lithoglyphus naticoides with egg capsules

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

apertural view of the shell of Lithoglyphus naticoidesapical view of the shell of Lithoglyphus naticoideslateral view of the shell of Lithoglyphus naticoidesumbilical view of the shell of Lithoglyphus naticoidesI 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:

outer side of an operculum of Lithoglyphus naticoidesInner side of the operculum:

inner side of an operculum of Lithoglyphus naticoidesReferences

no

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. water mite on Helisoma ancepsThe water mite is in the centre of the photo. It is on the mantle edge near the aperture. Detail cropped from the previous photo: water miteYou 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: water mite on Helisoma anceps with Ferrissia fragilisI 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:

eggs of Helisoma ancepsAnother cluster of eggs contains six more developed embryos:

eggs of Helisoma ancepsThis 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:

eggs of Helisoma anceps

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:

Bithynia transsilvanicaIt 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:

Bithynia transsilvanicaView of a foot:

Bithynia transsilvanicaAnother 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:

Bithynia transsilvanicaReferences

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.

Photo of the day (40): Bithynia leachii

Bithynia leachii is a widespread freshwater snail in Europe and it is a least concern species. This snail can live in natural and unpolluted wetlands only. In some areas, for example in the Czech Republic, it is critically endangered, because it inhabits a very limited area there.

There is seen on this frontal view, that the shell has very convex whorls and a very deep suture. This feature distinguish it from other Bithynia species.

Bithynia leachiiThe snail on the photo has the width of the shell 4.5 mm and the height of the shell is 5.5 mm. The snail of such size is adult already.

Right side view of the same snail:

Bithynia leachiiReferences

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.

Vavrová L., Cianfanelli S., Prie V., Georgiev D. & Ghamizi M. (2010). “Bithynia leachii“. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 18 January 2015.

Photo of the day (39): Valvata piscinalis

Valvata piscinalis is a freshwater snail native lowlands in Europe. It was introduced to the USA. Snails in the family Valvatidae are hermaphrodites.

The width of the shell of my Valvata piscinalis snail is 5.5 mm and the height of the shell is 5 mm. There is an operculum closing the aperture:

Valvata piscinalis

The frontal part of the foot is widened. The snail has a snout. Eyes are on the base of cephalic tentacles. It has one pallial tentacle on the right side of the body, that is visible as it is extended from the shell:

Valvata piscinalisThere is a penis above the right tentacle. The distal part of the penis is in the mantle cavity:

Valvata piscinalisA series of four similar photos follows:

Valvata piscinalis 2

Valvata piscinalis 3

Valvata piscinalis 4

Valvata piscinalis 5

Valvata piscinalis has a gill, but the gill is not visible on my photos. I should remove the detritus from the snail and I should take a photo of the gill too. Maybe next time.

No references.