Photo of the day (61): Ena montana

Ena montana is a species of a common land snail with Central European, Alpine and Carpathian distribution. It belong to the family Enidae. It is similar to Merdigera obscura, but they differ in size. Ena montana reach shell length up to 16 mm, while Merdigera obscura can grown up to 9 mm only.

Left side view of Ena montana crawling on a calcareous rock:

Ena montanaIt is the only species of Ena occurring in Central Europe. Other Ena species live in southern Europe.

My specimen comes from Velká Fatra Mountains, Slovakia. I have taken the photo in situ on a calcareous rock in the forest. But they also inhabits humid habitats in forests in lowlands.

It feeds mainly on living algae, sometimes on dead higher plants and rarely also on lichens.

References:

Falkner G., Obrdlík P., Castella E. & Speight M. C. D. 2001: Shelled Gastropoda of Western Europe. München: Friedrich-Held-Gesellschaft, 267 pp.

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). page 32 and 82.

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Photo of the day (60): shell headdress from New Guinea

This is an original tribal ceremonial men’s feather and shell headdress from Tambanum village on the Sepik River, East Sepik Province, northern Papua New Guinea. It was made in 19th century. It was shown in the exhibition “Crown jewels in the world’s history” in Ostrava museum at December 9, 2016 – March 5, 2017. It comes from the private collection of goldsmith Jürgen Abeler, owner of the Wuppertaler Uhrenmuseum, that was closed in 2016. The headdress is in the collection of Juwelier Abeler company (juwelier means jeweler) in Wuppertal now. I was happy to see it because it was the only thing on the exhibition, that contained shells.

feather and shell headdressLeft side view:
feather and shell headdressLarger shells are some species from the family Cypraeidae. It is probably Monetaria moneta, a common species, that was used as a shell money in various parts of the world including the New Guinea.

headdressThe smaller shells are also from marine gastropods, but I did not identify the species. Some headbands and other things from the area contain the same shells that are called “Nassa shells”. This does not mean the genus Nassa from the family Muricidae. It may mean some species from the family Nassariidae, that are commonly known as “Nassa mud snails”.

Other things of the headdress include feathers of a cassowary (Casuarius). There exist three extant species of cassowaries and all of them live in New Guinea. All of them have black feathers. According to the locality of the headdress and the distribution of cassowaries, feathers probably comes from the northern cassowary (Casuarius unappendiculatus) or from the dwarf cassowary (Casuarius bennetti).

There are also used animal teeth and number of strings.

Right side view:
feather and shell headdressI also do not know what is the material, from which “eyes” of this headdress were made. It looks like the same thing on the ancestor’s figure.

Such headdresses were and are used to emphasize the status of the owner. They are worn usually in festivals.

One more oblique view:
feather and shell headdressThe headdress also closely resembles for example feathered headdress for ancestor’s skull made by Asmat people.

That’s all. And if you can identify those small shells, let me to know. Thanks.

Photo of the day (59): Semilimax semilimax

Semilimax semilimax is a semi-slug with central European and Alpine distribution. It lives in moist forests. It is from the family Vitrinidae.

Left side view:
Semilimax semilimaxRight side view:
Semilimax semilimaxWhen I found those gastropods, I though, that I found two different species. Unfortunately all of them are the same species – Semilimax semilimax. I realized that in the lab some time later.

Six semi-slugs, five dark grey, one light grey and all of them are Semilimax semilimax:
Semilimax semilimaxIt is exactly as Welter Schultes wrote: “Animal light to dark grey”. They can vary in color even in one population as it is documented in this my record from central Moravia.

References

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). page 34 and page 111.

Welter Schultes F. (2013) Species summary for Semilimax semilimax. AnimalBase, last change 11 December 2013, accessed 28 November 2016.

Photo of the day (58): Pleurobranchus areolatus

Pleurobranchus areolatus is a sea slug from the family Pleurobranchidae.

It lives in Caribbean Sea, Brazil, Madeira and Canary Islands. Such distribution in western Atlantic and also in eastern Atlantic is called amphiatlantic (or amphi-Atlantic).

I thank my colleague Jessica Goodheart from the USA who kindly provided the photo.

This certain specimen of Pleurobranchus areolatus comes from Panama. You can find more information about sea slugs from Panama in her article “Identification guide to the heterobranch sea slugs (Mollusca: Gastropoda) from Bocas del Toro, Panama“.

This is the right side view of the slug. Its body is oval. There are numerous tubercles on the dorsum. Its rhinophores are in the frontal sinus. The gill is not visible because it is under the dorsum. There is also small internal shell inside the slug’s body, but the shell is not visible externally.

Pleurobranchus areolatus

Pleurobranchus areolatus from Panama by Jessica Goodheart, CC-BY-4.0

References

Goodheart J. A., Ellingson R. A., Vital X. G., Galvão Filho H. C., McCarthy J. B., Medrano S. M., Bhave V. J., García-Méndez K., Jiménez L. M., López G. & Hoover C. A. (2016). “Identification guide to the heterobranch sea slugs (Mollusca: Gastropoda) from Bocas del Toro, Panama“. Marine Biodiversity Records 9(1), p.56. doi:10.1186/s41200-016-0048-z

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 (56): Umbraculum umbraculum

Umbraculum umbraculum is quite large marine gastropod. It belong to the family Umbraculidae. It can grow up to 15 or 20 cm. The color may vary from yellow to brown or to red.

There are two populations worldwide. One population in Indo-West Pacific region and one population in east Atlantic and Mediterranean region. The later one was considered as a separate species Umbraculum mediterraneum. They are considered synonymous although there exist no review of the genus yet. My Umbraculum comes from Croatia and I have take following photos ex situ.

The shell is much smaller than the animal body. The shape of the shell is cap like or limpet like. The tip of the shell seems to be pointing in some direction sometimes, but the tip does not allow to identify the head region if the animal is retracted. The shell is always covered with some growths.

Umbraculum umbraculumThere are many tubercles on its mantle. Detail of tubercles:

Umbraculum umbraculumFoot is also circular even when the animal is crawling:
Umbraculum umbraculumThere is a gill on the right side of the body just below the shell. There are visible lamellae of the gill under the shell.
Umbraculum umbraculumIts dark eyes are between tentacles (rhinophores).
Umbraculum umbraculumI was no lucky to get a proper photo of its frontal slit region, that contain mouth and permanently protruded penis. Maybe next one.

Umbraculum umbraculum feeds on sponges (Porifera) from the class Demospongiae. Yes, SpongeBob should be afraid of this snail beast! Other ones can enjoy this snail species, because it certainly awaits for further interesting discoveries.

References

Rudman W. B., (1999 January 14) Umbraculum mediterraneum (Lamarck, 1819). Sea Slug Forum. Australian Museum, Sydney. accessed 2016 October 14.

Rudman W. B., (1999 March 7) Umbraculum umbraculum (Lightfoot, 1786). Sea Slug Forum. Australian Museum, Sydney. accessed 2016 October 14.

Photo of the day (55): Oxychilus glaber

Oxychilus glaber is a species of a herbivorous and carnivorous land snail in the family Oxychilidae. Its distribution is South European and Central European. It live in woods. Its umbilicus is narrow and its spire is high in comparison with other Oxychilus species.

My snail comes from the Czech Republic. It is not common species. It is nearly threatened in the Czech Republic and it is threatened with extinction in Germany.

Right side view:

Oxychilus glaberApical view:

Oxychilus glaberReferences

Species summary for Oxychilus glaber. AnimalBase, last change 8 December 2013, accessed 14 September 2016.

Beran L., Juřičková L. & Horsák M. 2005: Mollusca (měkkýši), pp. 69-74. – In: Farkač J., Král D. & Škorpík M. [eds.], Červený seznam ohrožených druhů České republiky. Bezobratlí. Red list of threatened species in the Czech Republic. Invertebrates. – Agentura ochrany přírody a krajiny ČR, Praha, 760 pp.

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). page 34 and page 108.

Wiese W. (2014) Die Landschnecken Deutschlands: Finden – Erkennen – Bestimmen. Quelle & Meyer, 352 pp., page 188.

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.

Photo of the day (53): Bolma rugosa

Bolma rugosa is a marine snail in the family Turbinidae. It is quite a big snail with a shell length up to 70 mm. Locality of my snail is Croatia. I have taken the following photos ex situ in the aquarium.

Bolma rugosaThose pointed structures bellow the shell are sensory structures, that are called epipodial tentacles. They are common structures in Vetigastropoda (one of main groups of gastropods).

Detail of epipodial tentacles:

epipodial tentacles of Bolma rugosaFoot view of Bolma rugosa:

Bolma rugosaFew other photos by other authors also shows epipodial tentacles on Bolma rugosa:

https://www.flickr.com/photos/o_torrents/5880559472/ at the top right corner of the photo.

or on the Circolo Attività Subacquee Chieri (Diving Club in Chieri, Italy) website at http://www.casc.it/VisPhotogallery.asp?Page=0&P=1&S=3051&F=1805&D=Bolma%20rugosa%2004.jpg

References

Wanichanon C., Laimek P., Chitchulanon N., Suphamungmee W., Apisawetakan S., Linthong V., Sretarugsa P., Kruatrachue M., Upatham E. S., Poomtong T. & Sobhon P. (2004). Sensory receptors on cephalic and epipodial tentacles of Haliotis asinina Linnaeus. Journal of Shellfish Research, 23(4): 1097-1106.

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