Boidae
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| Boa constrictor, Boa constrictor | |
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| Family: | Boidae Gray, 1825
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- Common names: boas, boids.[2]
The Boidae are a family of non-venomous snakes found in the Americas, Africa, Europe, Asia and some Pacific Islands. Relatively primitive snakes, adults are medium to large in size, with females usually larger than the males. The name is derived from the Latin term bos, meaning "cow", and is based on an old myth that boas pursue cows and suckle them until they are drained to death. Two subfamilies comprising eight genera and 43 species are currently recognized.[2]
Description
Like the pythons, boids have elongated supratemporal bones. The quadrate bones are also elongated, but not as much, while both are capable of moving freely so that 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 have 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 that they do coexist, the tendency is for them to occupy different habitats.[3]
It used to be said that boas are found in the New World and pythons in the Old World, but with boid species found on Madagascar, Fiji and the Solomon Islands, this is not quite true. Instead, it seems that they have survived in evolutionarily isolated areas. After all, South America had, until a few million years ago, a distinct fauna that included marsupial and mammals. With the land bridge to North America, boids have migrated north as placental mammals and colubrids have migrated south.
Geographic range
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]
Reproduction
Most species are ovoviviparous, with females giving birth to live young. This is in contrast to the pythons, which all lay eggs (oviparous).
Subfamilies
| Subfamily[2] | Authority[2] | Genera[2] | Species[2] | Common name | Geographic range[1] |
|---|---|---|---|---|---|
| Boinae | Gray, 1825 | 5 | 28 | True boas | Central and South America, Africa, Madagascar, Reunion Island, Mauritius, the Maluku Islands and New Guinea. |
| Erycinae | Bonaparte, 1831 | 3 | 15 | Old World sand boas | South and southeastern Europe, Asia Minor, north, central, west and east Africa, Arabia, central and southwestern Asia, India, Sri Lanka. Also in southwestern Canada, the western United States and northwestern Mexico. |
Type genus = Boa - Gray, 1825[1]
Taxonomy
Pythons are 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.
See also
- List of boine species and subspecies
- List of erycine species and subspecies
- Boidae by common name
- Boidae by taxonomic synonyms
- List of snakes, overview of all snake families and genera.
References
- ^ 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).
- ^ a b c d e f "Boidae". Integrated Taxonomic Information System. 14 July.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ 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).
- ^ Boidae at VMNH. Accessed 15 July 2008.
Further reading
- 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.