Calliostoma ligatum
| Calliostoma ligatum | |
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| A living specimen of Calliostoma ligatum crawling on a rocky substrate | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| (unranked): | clade Vetigastropoda |
| Superfamily: | Trochoidea |
| Family: | Calliostomatidae |
| Genus: | Calliostoma |
| Species: | C. ligatum |
| Binomial name | |
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Calliostoma ligatum (Gould, 1849) |
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| Synonyms | |
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Calliostoma ligatum,common name the blue top snail, is a small prosobranch trochid gastropod mollusk in the family Calliostomatidae, the Calliostoma top snails.
The conical, solid shell has well rounded globose whorls with 6 to 8 smooth spiral cords per whorl and no umbilicus. Its base is flattened. The surface is encircled by numerous spiral smooth riblets, their interstices closely finely obliquely striate. There are usually 7 to 9 riblets on the penultimate whorl, about 9 on the base. The spire is conic. The apex is acute. The sutures are impressed. There are about seven, convex whorls. The body whorl is and rounded (or a trifle angled) around the lower part, slightly convex beneath. The oblique aperture is rounded. The outer lip is fluted within, with a beveled opaque white submargin. The throat is pearly and iridescent;. The simple columella is arcuate.
The base color is chocolate brown to mauve with light tan raised cords, and the aperture is pearly white. The apex is darked and usually purple.
The shell is relatively heavy for its size, and its length and width are roughly equal. Length and width up to 24 mm.
Found from Alaska to San Diego, California.
Calliostoma ligatum is a broadcast spawner. Snails spawned in the laboratory in the San Juan Islands, WA, USA, during the months of February, March, and April, but only in water that was at least 10°C. Females release eggs in delicate strands of mucus that break down soon after release. These strands are 1-3mm wide and contain 1-4 eggs across the strand. Ten to ninety eggs are released per pulse, with multiple pulses of eggs released during each spawning event. Males release sperm as a milky white cloud. Fertilization occurs in the water. Eggs are just over 200um in diameter, and an egg with its protective gelatinous chorion is about 750um in diameter. Early development proceeds as the zygote undergoes cleavage in the spiral pattern typical of molluscs and other protostomes. Embryos in culture at 7-9°C reach the trochophore larval stage in 3 days, undergo torsion in 4.5-5 days, and hatch 6 days after fertilization. Veliger larvae stop swimming and begin crawling 9.5 days after fertilization and undergo metamorphosis into juvenile snails about 12 days after fertilization.
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Wikipedia