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.

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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

Photo of the day (52): Tonna galea

Tonna galea is a large sea snail with worldwide distribution in temperate and in tropical seas. I have taken these photos in Croatia.

Tonna galea one of the largest snails in the Mediterranean Sea. Because of its size and because its beautiful shell it is exploited or over-exploited as a food source and as a tourist souvenir.

This species is protected by 1979 Berne Convention on the Conservation of European Wildlife and Natural Habitats as a strictly protected species. Therefore is is protected by law in many European countries. For example in Croatia it is protected since 2013 by law. It is forbidden to capture, kill, trade, import, export, and so on.

Despite its protection, its population size is thought to be greatly declined. Exporting of empty shells abroad is also not allowed. Let them for local residents and maybe they will use them in some nice way like this:

Tonna galea
With Haworthia sp.:

Tonna galea
With Aloe sp.:

Tonna galea
References

Doxa C. K., Sterioti A., Kentouri M. & Divanach P. (2011). “Encapsulated development of the marine gastropod Tonna galea (Linnaeus, 1758) in captivity“. Journal of Biological Research 16: 304–307.

Katsanevakis S., Lefkaditou E., Galinou-Mitsoudi S., Koutsoubas D. & Zenetos A. (2008). “Molluscan species of minor commercial interest in Hellenic seas: Distribution, exploitation and conservation status“. Mediterranean Marine Science, 9: 77-118.

(1979). Berne Convention. Annex II.

(in Croatian) (2013). “Zakon o zaštiti prirode. [Nature Protection Act]”. Narodne novine«, broj 80/2013 [Official Gazette 80/13].

Photo of the day (51): Elisolimax from Madagascar

The photo of this land slug is from the tropical moist forest in northern Madagascar. It was identified according to the photo only. It is either Elisolimax bella or Elisolimax madagascariensis. Genus Elisolimax belong to the family Helicarionidae.

Locality: Madagascar, tropical moist forest, between Joffreville village and the entrance to the Amber Mountain National Park, coordinates: -12.502470, 49.201356, November 15, 2014. Photo by Martin Mandák.

I thank to Martin Mandák from the Czech Republic for taking the photo.

I thank to Owen Griffiths from Mauritius for the slug identification.

Elisolimax from Madagascar. Photo by Martin Mandák, CC-BY-4.0.

Elisolimax from Madagascar. Photo by Martin Mandák, CC-BY-4.0.

 

Photo of the day (50): Flabellina affinis

Flabellina affinis is a species of a nudibranch (Nudibranchia). Some nudibranchs really breathe by naked gills, but this species belong to a group of nudibranchs, that breathe by the whole body surface.

It is common species in the Mediterranean Sea. It feeds on colonial hydrozoids from the genus Eudendrium. It live in rocky habitat in the sublittoral zone not far from the shore.

I have taken photos in the lab (ex situ), so we take take a look at some anatomical features. Flabellina affinis can reach up to 50 mm, but my specimen is much smaller, about 20 mm. It is pink.

Flabellina affinisIt has a pair of tentacular foot corners (foot tentacles) – the most lower ones. It has a pair of labial tentacles (they are called as oral tentacles in other slug species). The top one ear-like structures are called rhinophores. There is visible small dark eye on the photo above. Eye is more likely on the base of rhinophores than on the base of labial tentacles.

Frontal view of the slug:

Flabellina affinisThe slug has cerata on its body. Cerata are in groups. There are from six to nine groups of cerata on the right side and on the left side of the body. My slug has seven groups of cerata, but the sixth group and the seventh group are not paired.

Flabellina affinisThe slug is small and it can crawl on the water level in the laboratory conditions. So there is also foot or ventral side visible on photos sometimes. There are visible genital apertures bellow the first group of cerata on the right side of the body on the following photos. They looks like two small tubercules. There is visible anus as a black dot on the right side between the first and second group of cerata. Anus looks like a small pointed tubercule:

Flabellina affinis

Flabellina affinisThere is a dark structure between the first and the second group of cerata, but I do not know what it is:

Flabellina affinis

Flabellina affinisReferences

Schulze A. & Wägele H. (1998) “Morphology, anatomy and histology of Flabellina affinis (Gmelin, 1791) (Nudibranchia, Aeolidoidea, Flabellinidae) and its relation to other Mediterranean Flabellina species“. Journal of Molluscan Studies 64(2): 2195-214. doi:10.1093/mollus/64.2.195

Photo of the day (49): Ambigolimax valentianus

Ambigolimax valentianus is a land slug from the family Limacidae. Its native distribution includes Iberian Peninsula only, but it is spreading in many other countries as an invasive species. It can live in greenhouses and similar habitats in cold areas only. It lives in greenhouses in Central Europe too. It is a pest in greenhouses and it is able to overpopulate and then it can be a serious pest. It can reach the length up to 70 mm.

Various views of the slug:

Ambigolimax valentianus

Ambigolimax valentianus

Ambigolimax valentianus

Ambigolimax valentianusThe foot is light gray:

Ambigolimax valentianusThere exist two forms of Ambigolimax valentianus: a form with two dark lateral bands and a a spotted form. The spotted form looks like this. It looks a bit yellow on the photo, but it is caused by the sunglight.

Ambigolimax valentianusIts eggs look like this. I found those eggs below the bowl for the potted plant.

Ambigolimax valentianusNotice the juvenile slug in the front. It is interesting that its egss will not survive temperatures above 33 °C.

A juvenile slug:

Ambigolimax valentianusAnother photo with juvenile slugs:

Ambigolimax valentianusThis species is also known as Lehmannia valentiana. In fact I did not known, that it could be placed in the genus Ambigolimax up today.

So I searched for reasons of its generic placement:

Klee et al. found out based on molecular phylogeny research of cytochrome-c oxidase I (COI) genes, that the genus Lehmannia is diphyletic in 2005. She also repeated the information in her thesis in 2013.

Rowson et al. confirmed such placement also according to the COI genes analysis in 2014. By the way, they did not comment this species in the PLoS article anyhow. They just shown the cladogram on the figure 5.

The results are:

Lehmannia marginata (O. F. Müller, 1774) still belong to the genus Lehmannia Heynemann, 1863, because it is the type species of the genus.

Lehmannia valentiana (Férussac, 1822) belong to the genus Ambigolimax Pollonera, 1887 as a Ambigolimax valentiana (Férussac, 1822). It is the type species of the genus Ambigolimax.

Lehmannia nyctelia (Bourguignat, 1861) also belong to the genus Ambigolimax as Ambigolimax nyctelius (Bourguignat, 1861).

There is a question, where will belong other 13 European species of Lehmannia. Especially those ones, whose reproductive system is not known.

References

Horsák M., Dvořák L. & Juřičková L. (2004) Greenhouse gastropods of the Czech Republic: current stage of research. Malacological Newsletter, 22: 141–147, page 143.

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 163.

Klee B., Falkner G. & Haszprunar G (2005). Endemic radiations of Limax (Gastropoda: Stylommatophora) slugs in Corsica – they came twice. In: Burckhardt D (ed.), 8. Jahrestagung der Gesellschaft für biologische Systematik, Basel 13.-16. September 2005, Abstracts of talks and posters: p.78. Basel (Naturhistorisches Museum). Organisms Diversity and Evolution 5, Electr. Suppl. 13: 75.

Nitz. B. (2013). Integrative systematics and biogeography of Limax (Gastropoda: Stylommatophora). Dissertation Thesis, Ludwig-Maximilians-Universität, München, 133 pp., page 105.

Rowson B., Anderson R., Turner J. & Symondson W. O. C. (2014). The slugs of Britain and Ireland: undetected and undescribed species increase a well-studied, economically important fauna by more than 20%. PLoS ONE 9(4): e91907. doi:10.1371/journal.pone.0091907

Stojnić B., Vukša M., Jokić G. & Čkrkić M. (2011). First record of introduced valencia slug, Lehmannia valentiana (Férussac, 1822), in Serbia. Pesticidi i fitomedicina, 26(3): 213–220. doi:10.2298/PIF1103213S

Udaka H., Mori M., Goto S. G. & Numata H. (2007). Seasonal reproductive cycle in relation to tolerance to high temperatures in the terrestrial slug Lehmannia valentiana. Invertebrate Biology, 126(2): 154–162.

Photo of the day (48): Pisania striata

Pisania striata is a marine snail in the Buccinidae family. It is a common species in the Mediterranean Sea. It is a scavenger or predator, but I found no detailed information about its food. Its habitat include rocky seashore (eulittoral zone or intertidal zone) and in the sublittoral zone not far from the shore (subtidal zone).

The height of the shell is up to 30 mm. There are fine spiral striae on its shell sculpture. The specific name striata is derived from those striate.

This one is from the Dubrovnik-Neretva County, southern Croatia. I have taken this photo in situ in very shallow water (about 2-3 cm) with an ordinary non-water-proof camera. Maybe it can be a motivation for anybody to take photos of marine animals with any camera. You just need to take care about reflections from the water level.

Its body is black. It extend its siphon through the siphonal notch during crawling, because there are chemoreceptors in the siphon and the snail is searching for its prey:

Pisania striata in situDetail of the snail:

Pisania striataApertural view shows, that its foot and some parts of its body are surprisingly light gray:

apertural view of Pisania striataYou can also compare the length of its siphon with tentacles:

foot of Pisania striataAnother view shows that the shape of its operculum is like a droplet:

a live Pisania striataReferences

Dance S. P. (ed.) (1974). The Encyclopedia of Shells. Blanford Press, ISBN 0713706988, page 145.