Photo of the day (79): Syrinx aruanus

Syrinx aruanus is a species of extant gastropod with the largest shell. The height of the shell can be up 72.2 cm. The largest specimen is stored in the Houston Museum of Natural Science. The volume of the animal is also very large. It is thought to be more voluminous than the largest extinct snail Campanile giganteum.

Syrinx aruanus is a marine sea snail and it belong to the family Turbinellidae.

I thank Jan Linhart, who has taken the photo of the shell in the Phuket Sea shell Museum, Thailand. I do not know exact measurements of this shell.

Syrinx aruanus

Shell of Syrinx aruanus in the Phuket Sea shell Museum. Photo by Jan Linhart, http://www.linhartmarketing.cz/, CC-BY-4.0.

Specimen of the shell height 91 cm was previously reported in the literature, but the reported size was wrong.

It may be also the heaviest extant snail (reaching up to 18 kg?), but I found no proper reference.

What are the limits of gastropods?

References

McClain C. R., Balk M. A., Benfield M. C., Branch T. A, Chen C., Cosgrove J., Dove A. D. M., Gaskins L. C., Helm R. R., Hochberg F. G., Lee F. B., Marshall A., McMurray S. E., Schanche C., Stone S. N. & Thaler A. D. 2015: Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. – PeerJ 3:e715.  DOI: 10.7717/peerj.715.

Taylor J. D. & Glover E. A. 2003: Food of giants – field observations on the diet of
Syrinx aruanus (Linnaeus, 1758) (Turbinellidae) the largest living gastropod. pp. 217-223. – In: Wells F. E., Walker D. I. & Jones D. S. (eds) 2003: The Marine Flora and Fauna of Dampier, Western Australia. Western Australian Museum, Perth.

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Gastropods in Phuket Sea shell Museum

Phuket Sea shell Museum is located at the south of the Phuket Island in Thailand.

I thank to Jan Linhart who has taken these photos of shells in the Phuket Sea shell Museum.

Collection of shells of sea snails from the family Haliotidae:

Haliotidae

Shells of Haliotidae. Photo by Jan Linhart, http://www.linhartmarketing.cz/, CC-BY-4.0.

Collection of shells of sea snails from the family Costellariidae:

Costellariidae

Shells of Costellariidae. Photo by Jan Linhart, http://www.linhartmarketing.cz/, CC-BY-4.0.

Collection of shells of sea snails from the family Terebridae:

Terebridae

Shells of Terebridae. Photo by Jan Linhart, http://www.linhartmarketing.cz/, CC-BY-4.0.

Stages of growth of the Charonia tritonis from the family Ranellidae:

Charonia tritonis

Stages of growth of the Charonia tritonis. Photo by Jan Linhart, http://www.linhartmarketing.cz/, CC-BY-4.0.

Stages of growth of the Turbinella pyrum from the family Turbinellidae:

Turbinella pyrum

Stages of growth of the Turbinella pyrum. Photo by Jan Linhart, http://www.linhartmarketing.cz/, CC-BY-4.0.

There are also other shells of gastropods and other shells of molluscs, such as ammonites and bivalves in the museum. It is worth to visit.

References

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Photo of the day (78): eggs of Tarantinaea lignaria

Those are egg capsules and embryos of a marine snail Tarantinaea lignaria from the family Fasciolariidae. Its synonyms are Pleuroploca lignaria  and Fasciolaria lignaria.

Egg capsules of Fasciolariidae are possible to identify to the genus level and to the species level. But majority of egg capsules of Fasciolariidae is not known.

Tarantinaea lignaria eggsThe egg capsules looks like on these photos. There is a circular opening in the middle of the cup. Newly hatched snails are escaping through the opening. There are visible embryos through the transparent wall of the capsules and there can be some few embryos inside one capsule. Exact number of embryos in one capsule was not published. It seems that this species may have a direct development.
Tarantinaea lignaria eggsThese egg capsules comes from the southern Croatia. I have taken these photos at September 28, 2016. Majority of snails hatched out already, but there are still some (live?) embryos visible in few capsules. There is also a juvenile snail on one of the capsules that probably (but not surely) belong to the same species.
Tarantinaea lignaria eggsDetail cropped from the previous photo shows a juvenile snail:
Tarantinaea lignaria eggsAnother view of the cluster of egg capsules:
Tarantinaea lignaria eggsDetail cropped from the previous photo shows two egg capsules:
Tarantinaea lignaria eggs The drawing of egg capsules of Tarantinaea lignaria is in the series on Gunnar Thorson’s collection of prosobranch egg capsules. I did not made proper measurements.

I thank to Dr. Paolo Russo from Italy for the species identification.

Gunnar Thorson (1906-1971) was professor of marine biology at the University of Copenhagen. He assembled the collection of egg capsules but he did not publish results of the whole collection by himself. Series of four monographs based on Thorson’s collection was published in 1992-2000 and it is very useful resource for anybody interested in this field.

References

D’Asaro C. N. 2000: Gunnar Thorson’s world-wide collection of prosobranch egg capsules: Fasciolariidae. Ophelia: 52(2), 77-112. DOI: 10.1080/00785236.1999.10409421

Photo of the day (77): egg laying of Phyllidia flava

Those are two marine slugs Phyllidia flava laying eggs. This is ventral view showing the foot of snails in an aquarium. Both of them are laying a spiral ribbon of eggs:
Phyllidia flava laying eggsThis species of sea slug is orange and its eggs are also orange. But you are lucky to see its eggs so clearly like this, because it usually lays eggs on the Axinella cannabina sponge, which is also orange.

It is a “camouflage” in general. This type of camouflage, when the animal visually resemble its surrounding is called “crypsis”. It is a “visual crypsis” and the animal has “cryptic coloration”.

Detail of the bigger slug cropped from the previous photo shows the head part on the left. The slug has its genital pore on the right side of the body so the genital pore is down on the photo:
Phyllidia flava laying eggsPhyllidia flava starts the laying in the center of the spiral, of course. But some species are known to start the spiral ribbon from the outside.(!) Most nudibranchs lays the spiral ribbon in an anticlockwise direction. There are very few nudibranchs that lays egg ribbons in a clockwise direction. Phyllidia flava lays eggs in the same way as the majority of nudibranchs in an anticlockwise direction. You are seeing an underside of the egg ribbon through the transparent glass of the aquarium so the ribbon appear clockwise on these three photos.

Two egg ribbons of Phyllidia flava from underside:
Phyllidia flava egg ribbonsReferences

Rudman, W. B., 2004 (August 2) Nudibranch egg masses – the direction they spiral. Sea Slug Forum. Australian Museum, Sydney.