Ecology

Associations

Known prey organisms

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Thermal pits detect prey: snakes
 

Thermal pits of vipers, pythons and boas detect infrared radiation emitted from prey using protein channels activated by heat.

     
  "Snakes possess a unique sensory system for detecting infrared radiation,  enabling them to generate a 'thermal image' of predators or prey.  Infrared signals are initially received by the pit organ, a highly  specialized facial structure that is innervated by nerve fibres of the  somatosensory system. How this organ detects and transduces infrared  signals into nerve impulses is not known. Here we use an unbiased  transcriptional profiling approach to identify TRPA1 channels as  infrared receptors on sensory nerve fibres that innervate the pit organ.  TRPA1 orthologues from pit-bearing snakes (vipers, pythons and boas)  are the most heat-sensitive vertebrate ion channels thus far identified,  consistent with their role as primary transducers of infrared stimuli.  Thus, snakes detect infrared signals through a mechanism involving  radiant heating of the pit organ, rather than photochemical  transduction. These findings illustrate the broad evolutionary tuning of  transient receptor potential (TRP) channels as thermosensors in the  vertebrate nervous system." (Gracheva et al. 2010:1006)
  Learn more about this functional adaptation.
  • Shuker, KPN. 2001. The Hidden Powers of Animals: Uncovering the Secrets of Nature. London: Marshall Editions Ltd. 240 p.
  • Gracheva EO; Ingolia NT; Kelly YM; Corder-Morales JF; Hollopeter G; Chesler AT; Sánchez EE; Perez JC; Weissman JS; Julius D. 2010. Molecular basis of infrared detection by snakes. Nature. 464: 1006-1011.
  • Fang J. 2010. Snake infrared detection unravelled. Nature News [Internet],
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
                                        
Specimen Records:244Public Records:157
Specimens with Sequences:223Public Species:19
Specimens with Barcodes:219Public BINs:19
Species:32         
Species With Barcodes:25         
          
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Barcode data

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Locations of barcode samples

Collection Sites: world map showing specimen collection locations for Boidae

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Wikipedia

Boidae

"boid" redirects here. For the artificial intelligence program, see Boids.
Common names: boas, boids,[2] boioids.

The Boidae are a family of nonvenomous snakes found in America, Africa, Europe, Asia, and some Pacific Islands. Relatively primitive snakes, adults are medium to large in size, with females usually larger than the males. Two subfamilies, comprising eight genera and 43 species, are currently recognized.[2]

Description[edit]

Like the pythons, boas have elongated supratemporal bones. The quadrate bones are also elongated, but not as much, while both are capable of moving freely so when they swing sideways to their maximum extent, the distance between the hinges of the lower jaw is greatly increased.[3]

Both families share a number of primitive characteristics. Nearly all have a relatively rigid lower jaw with a coronoid element, as well as a vestigial pelvic girdle with hind limbs that are partially visible as a pair of spurs, one on either side of the vent. In males, these anal spurs are larger and more conspicuous than in females. A long row of palatal teeth is present, and most species have a functional left lung that can be up to 75% as large as the right lung.[3][4]

Boids are, however, distinguished from the pythons in that none has postfrontal bones or premaxillary teeth, and that they give birth to live young. When labial pits are present, these are located between the scales as opposed to on them. Also, their geographical distributions are almost entirely mutually exclusive. In the few areas where they do coexist, the tendency is for them to occupy different habitats.[3]

Fossil of Boavus idelmani, an extinct species of boa

Formerly, boas were said to be found in the New World and pythons in the Old World, but with boid species present in Madagascar, Fiji, and the Solomon Islands, this is not quite accurate; instead, it seems they have survived in evolutionarily isolated areas. South America was isolated until a few million years ago, with a fauna that included marsupials and other distinctive mammals. With the formation of the Panamanian land bridge to North America about three million years ago, boids have migrated north as colubrids (and various Nearctic mammals) have migrated south, as part of the Great American Interchange.

Common names[edit]

The Old Tupi name for such snakes was mbói, which figures in the etymology of names such as jibóia and boitatá (the Brazilian name for the mythical giant anaconda).

Geographic range[edit]

They are found in Northern, Central and South America, the Caribbean, southeastern Europe and Asia Minor, Northern, Central and East Africa, Madagascar and Reunion Island, the Arabian Peninsula, Central and southwestern Asia, India and Sri Lanka, the Moluccas, and New Guinea through to Melanesia and Samoa.[1]

Feeding[edit]

Prey is killed by constriction; after an animal has been grasped to restrain it, a number of coils are hastily wrapped around it. Then, by applying and maintaining sufficient pressure to prevent it from inhaling, the prey eventually succumbs due to asphyxiation. Recently, the pressures produced during constriction have been suggested as the cause of cardiac arrest by interfering with blood flow, but this hypothesis has not yet been confirmed.

Larger specimens usually eat animals about the size of a house cat, but larger food items are not unknown: the diet of the common anaconda, Eunectes murinus, is known to include subadult tapirs. Prey is swallowed whole, and may take several days or even weeks to fully digest. Despite their intimidating size and muscular power, they are generally not dangerous to humans.

Contrary to popular belief, even the larger species do not crush their prey to death; in fact, prey is not even noticeably deformed before it is swallowed. The speed with which the coils are applied is impressive and the force they exert may be significant, but death is caused by suffocation, with the victim not being able to move its ribs to breathe while it is being constricted.[5][6][7]

Reproduction[edit]

Most species are ovoviviparous, with females giving birth to live young. This is in contrast to the pythons, which all lay eggs (oviparous).

Subfamilies[edit]

Subfamily[2]Taxon author[2]Genera[2]Species[2]Common nameGeographic range[1]
BoinaeGray, 1825528True boasCentral and South America, Africa, Reunion Island, Mauritius, the Maluku Islands and New Guinea
ErycinaeBonaparte, 1831315Old World sand boasSouth and southeastern Europe, Asia Minor, north, central, west and east Africa, Arabia, central and southwestern Asia, India, Sri Lanka, southwestern Canada, the western United States, and northwestern Mexico
SanziniinaeRomer, 195623Madagascan boasMadagascar
Candoiinae[a]Pyron, Burbink & Wiens, 201314Bevel-nosed boasOceania (excluding New Zealand)

Type genus = Boa - Gray, 1825[1]

Taxonomy[edit]

Pythons were sometimes classified as a subfamily of Boidae, the Pythoninae, but are in this case listed under their own family, the Pythonidae. In the same way, the Old World sand boas, the Erycinae, are also frequently listed under their own family, the Erycidae. Additionally, morphological studies place the subfamily Ungaliophiinae in Tropidophiidae, whereas all molecular analyses place them as sister group of Charina-Lichanura clade, within Boidae.

See also[edit]

References[edit]

  1. ^ a b Traditionally placed in Boinae
  1. ^ a b c d McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  2. ^ a b c d e f "Boidae". Integrated Taxonomic Information System. Retrieved 14 July 2008. 
  3. ^ a b c Parker HW, Grandison AGC. 1977. Snakes -- a natural history. Second Edition. British Museum (Natural History) and Cornell University Press. 108 pp. 16 plates. LCCCN 76-54625. ISBN 0-8014-1095-9 (cloth), ISBN 0-8014-9164-9 (paper).
  4. ^ Boidae at VMNH. Accessed 15 July 2008.
  5. ^ Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. ISBN 0-8069-6460-X. [page needed]
  6. ^ Stidworthy J (1974). Snakes of the World. Grosset & Dunlap. ISBN 0-448-11856-4. 
  7. ^ Carr, Archie Fairly (1963). The Reptiles. Life Nature Library. New York: Time. LCCN 63012781. [page needed]
  • Kluge AG. 1991. Boine Snake Phylogeny and Research Cycles. Misc. Pub. Museum of Zoology, Univ. of Michigan No. 178. PDF at University of Michigan Library. Accessed 8 July 2008.
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