Nucella
Nucella emarginata with egg capsules, Morro beach State Beach, Morro Bay, California
Nucella is the name of a genus of medium-sized snails from the family of whelks, which is Circumboreal represented in the North Atlantic and North Pacific.
Features
The medium sized, solid, double cone-shaped to spindle-shaped or egg-shaped housing of Nucella species have a well-developed thread with up to 7 whorls and a short Siphonalkanal. The sculpting is not very pronounced, so there may be axially low transverse ribs or fins. At spiral sculpturing fine lines, narrow longitudinal grooves or wider longitudinal ribs may occur. On the inside of the outer lip teeth may occur, or even missing, some species have also a sting. Moreover, spines absent on the housing. The columella is smooth. The operculum is horny with the nucleus at the front edge.
The snails have a flattened head with two sensors, where about one-third length from the base out one eye at a sitting. The distance is small and does not protrude over the edge of the housing. Is the accessory bore organ (ABO ), an acid gland to dissolve lime on the sole of the foot.
The snails are dioecious with internal fertilization. Eggs are laid in mostly yellowish, more or less flask-shaped egg capsules, each containing several hundred eggs, of which only about 10 to 25 develop, while the others serve as Nähreier. The entire development of the veliger stage takes place in the egg capsule, so that after several months slip finished small snails. Among other things, the basis of this criterion, but also based on the position of the genus Nucella ABO of Purpura and Thais is deferred.
The snails of the genus Nucella feed primarily on barnacles and mussels, to a lesser extent of snails. In the shell of the prey is drilled with the radula under the action of an acid secretion from the ABO a hole and then the long, thin proboscis brought by this to the victim. In other cases, the snail reached the flesh of the victim, by pressed their proboscis through the gaps of the shell.
History of systematics
Nucella in Latin means " nutlet ". The genus name Nucella is first mentioned in 1798 by Peter Friedrich Röding in the catalog of Conch Collection of Joachim Friedrich Bolten with 5 species. From this date, however, only a species name is valid, Nucella lapillus, with one of the other species names, Nucella theobroma, is synonymized. This type Nucella lapillus, the type species of the genus, was described by Linnaeus as Buccinum lapillus, and presented by Jean -Baptiste de Lamarck in 1822 in the genus Purpura Bruguiere in 1789, which included about 50 species. Thus, the Nordic purple snail has long been known under the name of Purpura lapillus. Through a revision of the genus Purpura this was limited to a few species of Indo-Pacific, including the type species Purpura persica. For Purpura lapillus another genus name was needed. From Röding were two names are available, Nucella and Thais. Said of Röding Nucella lapillus did not agree with the type of Linnaeus, to which tempted some authors to give the type the name Thais lapillus. In Nucella theobroma just mentioned there of Röding but it is in fact the Nordic purple snail, so that ultimately the choice must fall on the oldest genus name Nucella.
According to the World Register of Marine Species belonging to the genus Nucella include the following types:
- Nucella canaliculata ( Duclos, 1832)
- Nucella castanea ( Küster, 1886)
- Nucella dubia ( Krauss, 1848)
- Nucella emarginata ( Deshayes, 1839)
- Nucella freycinetii ( Deshayes, 1839)
- Nucella fuscata (Forbes, 1850)
- Nucella heyseana ( Dunker, 1882)
- Nucella lamellosa ( Gmelin, 1791)
- Nucella lapillus (Linnaeus, 1758)
- Nucella lima ( Gmelin, 1791)
- Nucella Ostrina ( Gould, 1852)
- Nucella rolani ( Bogi & Nofroni, 1984)
- Nucella squamosa ( Lamarck, 1816)
- Nucella wahlbergi ( Krauss, 1848)