King helm snail
| King helm snail | ||||||||||||
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Cassis tuberosa , Thelma Dias, Brazil, 2010 |
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| Scientific name | ||||||||||||
| Cassis tuberosa | ||||||||||||
| ( Linnaeus , 1758) |
The king helm snail or gnarled balaclava ( Cassis tuberosa ) is a snail from the family of helmet snails (genus Cassis ) that is common in the western Atlantic and feeds on sea urchins .
features
The large and heavy snail shell of Cassis tuberosa has a conspicuously wide, triangular parietal shield on the spindle. The outer lip of the case mouth is serrated on the inside. The surface of the shell is brown-orange to pink salmon with a dark brown spot in the center of the parietal shield. The teeth of the outer lip of the case mouth are ivory with dark brown spots in between. The body is covered with three spiral threads made of knots and a fine, net-like sculpture. The house becomes up to 30 cm long in adult snails.
distribution and habitat
Cassis tuberosa is found in the western Atlantic Ocean from North Carolina to Brazil and Cabo Verde including the Caribbean and Antilles . It lives in the intertidal zone and at sea depths of up to 27 m on sandy ground in seagrass meadows of Thalassia , often buried in the sand.
Life cycle
Like other helmet snails, Cassis tuberosa is separate sexes. The male mates with the female with his penis . Egg capsules and larval development are similar to those of other helmet snails. The capsules are typically deposited in a layer on brown algae of the genus Padina ( funnel algae ) at a depth of about 2 m during the day , a clutch containing about 200 vascular orange capsules. Each capsule contains several hundred eggs, most of which develop into embryos. This is followed by a pelagic phase as Veliger larvae up to metamorphosis to the finished snail.
food
As a nocturnal predatory snail, Cassis tuberosa specializes in sea urchins , with at least 14 sea urchin species reported as prey for the snail in laboratory and field studies. According to this, it mainly eats the diadem sea urchin Diadema antillarum as well as Echinometra lucunter , Lytechinus variegatus and Tripneustes ventricosus as well as the sand dollar Mellita quinquiesperforata and Leodia sexiesperforata . The snail moves at 3 mm / s when hunting, which is faster than a sea urchin. Once it has discovered the prey and has come close enough, it raises the front part of the foot and lowers it on the victim, whose spines seldom penetrate the snail's foot. The proboscis is brought between the spines to the shell of the sea urchin. With the help of its foot, the predatory snail breaks off the spines in a small area, where, with the help of the radula , a hole about 5 mm in size is drilled by cutting out a round disc under the action of the acid saliva, and the snail with its radula can reach the prey's organs. The saliva also serves to paralyze the prey, which can no longer move its pedicellarians , suckers and spines. The eating process takes about 1 to 3 hours. With the exception of the stomach contents and the tissue on Aristotle's lantern , all the soft tissues of the sea urchin are eaten, as well as parts of the spines and suckers. The helmet snail has a significant influence on the population dynamics of the sea urchin species concerned. In comparative laboratory studies from 1971, however , Cassis tuberosa preferred Echinometra lucunter to Tripneustes ventricosus as prey, while they let the diadem sea urchin Diadema antillarum and Eucidaris tribuloides as well as the heart urchin Meoma ventricosus and the sand dollar Mellita quinquiesperforata , which is also eaten in the open by young king shells .
Importance to humans
Cassis tuberosa is collected for both its shell and its flesh, so that humans can be considered a major enemy. It is therefore endangered in many places.
literature
- Thelma Lúcia Pereira Dias, Ellori Laíse Silva Mota, Rafaela Cristina de Souza Duarte, Rômulo Romeu Nóbrega Alves (2017): What do we know about Cassis tuberosa (Mollusca: Cassidae), a heavily exploited marine gastropod? Ethnobiology and Conservation 6, pp. 16-28.
Web links
Individual evidence
- ^ A b c Gracia, Adriana y Juan Manuel Díaz N. (): Cassis flammea . In: Ardila, GR Navas, J. Reyes (eds.): Libro rojo de invertebrados marinos de Colombia. Pp. 86-87. Ministerio de Medio Ambiente, INVEMAR, Bogotá 2002.
- ^ A b J. J. Welch (2010): The 'Island Rule' and Deep-Sea Gastropods: Re-Examining the Evidence . PLoS ONE 5 (1), p. E8776. doi : 10.1371 / journal.pone.0008776 .
- ^ Cassis tuberosa (Linnaeus, 1758). Malacolog.
- ↑ a b c Thelma Lúcia Pereira Dias, Ellori Laíse Silva Mota, Rafaela Cristina de Souza Duarte, Rômulo Romeu Nóbrega Alves (2017): What do we know about Cassis tuberosa (Mollusca: Cassidae), a heavily exploited marine gastropod? Ethnobiology and Conservation 6, pp. 16-28.
- ↑ Roger N. Hughes, Helen PI Hughes (1971): A study of the gastropod Cassis tuberosa (L.) preying upon sea urchins. Journal of Experimental Marine Biology and Ecology 7 (3), pp. 305-314, doi: 10.1016 / 0022-0981 (71) 90012-8 .