Cone snails

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Cone snails
Conus textile, alternatively Cylinder textile, Brehms Thierleben (1887), p. 283

Conus textile , alternatively Cylinder textile , Brehms Thierleben (1887), p. 283

Systematics
Superordinate : Caenogastropoda
Order : Sorbeoconcha
Subordination : Hypsogastropoda
Partial order : Neogastropoda
Superfamily : Conoidea
Family : Cone snails
Scientific name
Conidae
Rafinesque , 1815

The cone snails (Conidae) are predatory snails that live in tropical seas with only a few exceptions. The approximately 1000 species are all assigned to the genus Conus or alternatively divided into 98 independent genera, but according to Philippe Bouchet (2015) divided into 8 recent and 7 fossil genera, with around 760 species still belonging to the genus Conus , which in turn have 57 subgenera includes.

features

The mostly nocturnal cone snails are all carnivores. Many species hide in the mud or sandy soil during the day. Most species such as the Mediterranean cone in the Mediterranean , Conus cedonulli in the Caribbean and the black and white cone snail in Indo eat bristle worms , others like the marble cone and the Conus textile in the Indo-Pacific are on molluscs specialized and feed on other snails , isolated - so the ermine tail in the Caribbean and the deep-sea cone snail Profundiconus smirnoides - also from cephalopods . Still other species that produce particularly dangerous poisons eat fish . For hunting, most of them, like the striped cone snail and the magic cone in the Indo-Pacific and the ermine tail in the Caribbean, use a harpoon that has developed from a tooth of the radula . The map cone and the tulip cone in the Pacific, on the other hand, first anesthetize the fish with insulin before swallowing them and pricking them in the mouth with poisonous radula teeth. The cone snail's radula has a single, needle-like tooth at its tip, which is hollow and communicates with a venomous gland. There are reserve teeth in a pocket because the harpoon, which is "shot" through the trunk into the prey, is lost. Most species specialize in specific prey. The California cone snail , the only cone snail native to the North American Pacific coast, has a broader range of prey and eats bristle worms, fish and snails as well as clams and crabs .

Cone snails are separate sexes.

The hermit crab Trizopagurus strigatus in an algae-covered enclosure of Conus mustelinus (alternatively also called Rhizoconus mustelinus ).

As an adult, the hermit crab Trizopagurus strigatus only uses the shells of cone snails to protect its soft abdomen. Its body is specially flattened to fit into the narrow openings of the cone snail shells.

Living map cone ( Conus geographus , alternatively Gastridium geographus ) with outstretched foot and siphon
Conus striatus (alternatively Pionoconus striatus ) while eating a fish, near Guam .
Diversity of housing forms within the Conidae

Poison and effect

The poisons of the cone snails are called conotoxins and are neurotoxins that can also be dangerous for humans. Some species can even be fatal. In 1993, 16 deaths were reported, 12 of which were due to Conus geographus . C. textile caused two fatal accidents . Other dangerous cone snails are: C. aulicus , C. marmoreus , C. omaria , C. striatus and C. tulipa . In general, the toxins of the bristle worm-eaters are considered less dangerous for humans, while the poisons of the mollusc- and especially fish-eating species can lead to more severe poisoning. This is because the swimming fish hit by the snail must be dead on the spot - snails are slow and cannot make a fish swim several hundred meters further. However, these extremely poisonous species do not live in shallow water. Practically the only deaths are those divers who reach for the cone snails with their hands.

Each species produces a poison cocktail of up to several hundred oligopeptides , i.e. short chains of amino acids. There are several classes of these that work in different ways, for example by blocking certain receptors for neurotransmitters at the synapses of nerve cells or by blocking ion channels . It is the interaction of several poison components that makes conotoxins so effective and dangerous.

Antitoxins are not known. Cone snail victims can only be treated symptomatically and with intensive care.

Medicinal effect

A poison from the cone snail Conus magus (alternatively Pionoconus magus ) is used as a pain reliever ( analgesic ). The ziconotide is a non-opioid analgesic that is more effective than known pain relievers. The poison is considered a possible substitute for morphine .

use

Cone snails are coveted collector's items because of their beautifully patterned housing. Together with the cowrie snails , they are probably the most sought after and traded for specialized collectors. Probably the most famous cone snail is the Conus gloriamaris (alternatively Cylinder gloriamaris ). Although already described in 1777, only two dozen examples were known until the 1950s and the cases fetched four-digit prices in US dollars until the 1970s . New habitats have now been found and prices have dropped into the low three-digit range. Other sought-after and expensive species that resemble Conus gloriamaris are Conus bengalensis (alternatively Cylinder bengalensis ), Conus milneedwardsi (alternatively Leptoconus milneedwardsi ) and Conus excelsus (alternatively Turriconus excelsus ).

Systematics

The species composition of the family has changed fundamentally several times in recent years.

Bouchet and Rocroi divided the large cone snail family into seven subfamilies in 2005, most of which were raised to family rank when a revision was made in 2011:

The World Register of Marine Species lists according to a processing by Philippe Bouchet 8 recent and 7 fossil species, with about 760 species alone still to the genus Conus are, in turn, 57 subgenera includes, during Conasprella 149 has usually extant species. The basis for this is a system of the Conidae family, which was drawn up in 2015 by Puillandre, Duda, Meyer, Olivera and Bouchet with initially four genera and according to which a large part of the species - around 85% - still belong to the genus Conus with 57 subgenera, but they do Conasprella with 11 subgenera and Profundiconus with a dozen species each and the monotypical Californiconus come:

According to an alternative system, 98 genera with a total of 760 species in the cone snail family in the narrower sense were listed in the World Register of Marine Species . The reassignment into genera largely corresponds to the work by Tucker & Tenorio from 2009. Because this division into genera is not certain, all species or most of the species of the cone snail family are alternatively placed in the genus Conus .

As of March 15, 2015

The genus Mitrolumna Bucquoy, Dautzenberg & Dollfus , 1883 is now a sub-genus of the genus Mitromorpha Carpenter , 1865, which is now the nominotypical genus of the Mitromorphidae family . Mangia Risso , 1826, also previously included in the cone snail family, became the nominotypic genus of the Mangiidae family , Clathurella Carpenter , 1857 is now the type genus of the Clathurellidae family .

Individual evidence

  1. ^ A b c Philippe Bouchet: Conidae Fleming, 1822 . In: WoRMS, World Register of Marine Species, 2014, accessed March 12, 2015
  2. ↑ a b P. Bouchet, YI Kantor, A. Sysoev & N. Puillandre: A new operational classification of the Conoidea. Journal of Molluscan Studies, 77, pp. 273–308, 2011 ( online )
  3. ↑ N. Puillandre, TF Duda, C. Meyer, BM Olivera, P. Bouchet (2015): One, four or 100 genera? A new classification of the cone snails. Journal of Molluscan Studies 81, pp. 1-23.

literature

  • Philippe Bouchet and Jean-Pierre Rocroi: Part 2: Working classification of the Gastropoda . In: Malacologia . tape 47 , 2005, ISSN  0076-2997 , p. 239-283 .
  • Victor Millard: Classification of the mollusca: a classification of world wide mollusca . Millard, Rhine Road, South Africa 1997, ISBN 0-620-21261-6 .
  • Winston Ponder and David Lindberg: Towards a phylogeny of gastropod molluscs: an analysis using morphological characters . In: Zoological Journal of the Linnean Society . tape 119 , 1997, ISSN  0024-4082 , pp. 83-265 .
  • Frank Riedel: Origin and evolution of the "higher" Caenogastropoda . In: Berlin Geoscientific Treatises (=  Series E ). tape 32 . Free University of Berlin, 2000, ISBN 3-89582-077-6 , pp. 1-240 .
  • Alan J. Kohn (1956): Piscivorous Gastropods of the Genus Conus. Proceedings of the National Academy of Sciences of the United States of America 42, pp. 168-171.
  • Alan J. Kohn, PR Saunders, S. Wiener (1960): Preliminary Studies on the Venom of the Marine Snail Conus. Annals of the New York Academy of Sciences 90, pp. 706-725.
  • Alan J. Kohn (1963): Venomous Marine Snails of the Genus Conus. In: Hugh L. Keegan, WV MacFarlane (Eds.): Venomous and Poisonous Animals and Noxious Plants of the Pacific Area. Pp. 83-96. Pergamon Press, Oxford.
  • Thomas F. Duda, Alan J. Kohn, Stephen R. Palumbi (2001): Origins of diverse feeding ecologies within Conus, a genus of venomous marine gastropods. Biological Journal of the Linnean Society 73, pp. 391-409.
  • Vidal Haddad Junior, João Batista de Paula Neto, Válter José Cobo (2006): Venomous mollusks: the risks of human accidents by conus snails (Gastropoda: Conidae) in Brazil. Revista da Sociedade Brasileira de Medicina Tropical 39 (5), pp. 1-3.
  • Baldomero M. Olivera, Jon Seger, Martin P. Horvath, Alexander Fedosov (2015): Prey-capture Strategies of Fish-hunting Cone Snails: Behavior, Neurobiology and Evolution. Brain, Behavior and Evolution 86 (1), pp. 58-74. PMC 4621268 (free full text)
  • Helena Safavi-Hemami, Joanna Gajewiak, Santhosh Karanth, Samuel D. Robinson, Beatrix Ueberheide, Adam D. Douglass, Amnon Schlegel, Julita S. Imperial, Maren Watkins, Pradip K. Bandyopadhyay, Mark Yandell, Qing Li, Anthony W. Purcell , Raymond S. Norton, Lars Ellgaard, Baldomero M. Olivera (2015): Specialized insulin is used for chemical warfare by fish-hunting cone snails. Proceedings of the National Academy of Sciences of the United States of America 112 (6), pp. 1743-1748.

Web links

Commons : Cone Snails  - Collection of images, videos, and audio files