Strombidae

Strombidae
Three shells of three species in the family Strombidae: lower left Laevistrombus canarium, upper center Lambis lambis, lower right Euprotomus aurisdianae
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
clade: Caenogastropoda
clade: Hypsogastropoda
clade: Littorinimorpha
Superfamily: Stromboidea
Family: Strombidae
Rafinesque, 1815
Genera

See text

Strombidae, commonly known as the true conchs, is a taxonomic family of medium-sized to very large sea snails, marine gastropod mollusks in the superfamily Stromboidea.

The family Strombidae includes the genera Strombus, Lambis, Tibia, and their allies. Many more species existed in the geological past than are now extant.

The term true conchs, being a common name, does not have an exact meaning. It may refer generally to any of the Strombidae[1] but sometimes is used more specifically to include only Strombus and Lambis[2] or just Strombus itself.[3]

Contents

Distribution

Strombid gastropods live mainly in tropical and subtropical waters. These animals are widespread in the Indo-West Pacific, where most species and genera occur.[4] Nearly forty of the living species that used to belong to the genus Strombus can be found in the Indo-Pacific region.[5] They also occur in the eastern Pacific and Western Atlantic, and a single species can be found on the African Atlantic coast.[4] Six species of strombids are found in the wider Caribbean region, including the queen conch Lobatus gigas, the goliath conch Lobatus goliath, the hawk-wing conch Lobatus raninus, the rooster tail conch Lobatus gallus, the milk conch Lobatus costatus, the West Indian fighting conch Strombus pugilis and the Florida fighting conch Strombus alatus. Until recently, all of these species were placed in the genus Strombus, but now many species are being moved into new genera.[6]

Morphology and life habits

Strombids have long eye stalks, a long and narrow aperture, and a siphonal canal. The shell margin has an indentation near the anterior end which accommodates one of the eye stalks. This indentation is called a strombid or stromboid notch. The stromboid notch may be more or less conspicuous depending on the species. The shell of most species in this family grow a flared lip upon reaching sexual maturity, and they lay eggs in long, gelatinous strands. The genera Strombus and Lambis have many similarities between them, both anatomical and reproductive, though their shells show some conspicuous differences.

Strombid were widely accepted as carnivores by several authors in the 19th century, an erroneous conception that persisted for several decades into the first half of the 20th century. This ideology was probably born in the writings of Lamarck, who classified strombids alongside other supposedly carnivorous snails, and was posteriorly recovered by other authors. However, the many claims of those authors were never supported by the observation of animals in their natural habitat.[7] Nowadays, strombids are known to be specialized herbivores and occasional detritivores. They are usually associated with shallow water reefs and seagrass meadows.[8]

Behavior

Unlike most snails, which glide slowly across the substrate on their foot, strombid gastropods have a characteristic means of locomotion, using their pointed, sickle-shaped, horny operculum to propel themselves forward in a so called leaping motion.[1][9]

Burrowing behaviour, in which an individual sinks itself entirely or partially into the substrate, is also frequent among strombid gastropods. The burrowing process itself, which involves distinct sequential movements and sometimes complex behaviours, is very characteristic of each species. Usually, large strombid gastropods such as the queen conch Eustrombus gigas and the spider conch Lambis lambis, won't bury themselves, except during their juvenile stage. On the other hand, smaller species such as the dog conch Strombus canarium and Strombus epidromis may bury themselves even after adulthood, though this is not an absolute rule.[10]

Taxonomy

For a long time all conchs and their allies (the strombids) were classified in only two genera : Strombus and Lambis. This classification can still be found in many textbooks and on websites on the internet. Based on molecular phylogeny (independent of morphological data) [8] and a well-known fossil record, the genus Strombus has been subdivided in several new genera.[11]

Genera

The family Strombidae comprises several genera (extinct genera are marked with a dagger †), including[11]:

Genera brought into synonymy 

Cladograms

A cladogram (a tree of descent) based on an extensive morpho-anatomical analysis of representatives of Aporrhaidae, Strombidae, Xenophoridae and Struthiolariidae was proposed by Simone (2005).[12] A simplified part of this analysis, comprising only Strombidae representatives, is depicted below:

Strombidae

Terebellum terebellum




Canarium urceus




Conomurex luhuanus




Tricornis raninus




Lambis lambis




Strombus




Eustrombus



Aliger









Another cladogram, this time based on sequences of nuclear histone H3 and mitochondrial cytochrome-c oxidase I (COI) genes was proposed by Latiolais et al. (2006). The phylogenic relations of (32 analyzed) species that used to belong or still belong in the genus Strombus and Lambis are shown bellow[8]:

 


 Eastern Pacific and Atlantic 






Strombus gallus



Strombus gigas




Strombus costatus





Strombus raninus



Strombus peruvianus





Strombus galeus




Strombus latus







Strombus pugilis



Strombus alatus




Strombus gracilior




Strobus granulatus







Strombus bulla



Strombus aurisdianae




Strombus vomer






Strombus gibberulus



Strombus luhuanus





 Lambis 


Lambis chiragra



Lambis truncata




Lambis lambis





Strombus taurus



Strombus sinuatus












Strombus maculatus



Strombus mutabilis





Strombus microurceus



Strombus labiatus







Strombus fragilis



Strombus urceus




Strombus dentatus







Strombus canarium



Strombus vittatus




Strombus epidromis






Strombus fusiformis



Strombus haemostoma





Strombus wilsoni



References

  1. ^ a b Abbott, R. T.; Dance, S. P. (2000). Compendium of Seashells. California: Odyssey Publishing. p. 75. ISBN 0-9661720-0-0. 
  2. ^ Goodenough, W. H. & Sugita, H. (1980). "Trukese-English dictionary". Philadelphia: American Philosophical Society. p. 235]
  3. ^ worldwideconchiology.com Strombidae article
  4. ^ a b Beesley, P. L.; Ross, G. J. B.; Wells, A. (1998). Mollusca: The Southern Synthesis. Fauna of Australia: Part B. Melbourne, AU: CSIRO Publishing. p. 766. ISBN 0 643 05756 0. 
  5. ^ Abbott, R.T. (1960). "The genus Strombus in the Indo-Pacific". Indo-Pacific Mollusca 1(2): 33-144
  6. ^ Landau, B. M.; Kronenberg G. C.; Herbert, G. S. (2008). "A large new species of Lobatus (Gastropoda: Strombidae) from the Neogene of the Dominican Republic, with notes on the genus". The Veliger (Santa Barbara: California Malacozoological Society, Inc.) 50 (1): 31–38. ISSN 0042-3211. 
  7. ^ Robertson, R. (1961). "The feeding of Strombus and related herbivorous marine gastropods". Notulae Naturae of the Academy of Natural Sciences of Philadelphia (343): 1–9. 
  8. ^ a b c Latiolais J. M., Taylor M. S., Roy K. & Hellberg M. E. (2006). "A molecular phylogenetic analysis of strombid gastropod morphological diversity". Molecular Phylogenetics and Evolution 41: 436-444. doi:10.1016/j.ympev.2006.05.027. PDF.
  9. ^ Parker, G. H. (1922). "The leaping of the stromb (Strombus gigas Linn.)". Journal of Experimental Zoology 36: 205-209.
  10. ^ Savazzi, E. (1989). "New observations on burrowing in strombid gastropods". Stuttgarter Beiträge zur Naturkunde. Serie A (Biologie) (Staatliches Museum für Naturkunde) (434): 1–10. ISSN 0341-0145. 
  11. ^ a b Strombidae Rafinesque, 1815.  Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=23123  on 22 March 2011.
  12. ^ Simone, L. R. L. (2005). "Comparative morphological study of representatives of the three families of Stromboidea and the Xenophoroidea (Mollusca, Caenogastropoda), with an assessment of their phylogeny". Arquivos de Zoologia (São Paulo, Brazil: Museu de Zoologia da Universidade de São Paulo) 37 (2): 141–267. ISSN 0066-7870. http://www.revistasusp.sibi.usp.br/pdf/azmz/v37n2/a01v37n2.pdf. 

Further reading

External links