Ular-derik besar
Ular-derik besar atau ular-derik sejati adalah kelompok ular derik yang hanya bisa ditemukan di Amerika tersebar luas mulai dari Kanada bagian selatan lalu ke selatan hingga Brasil bagian utara dengan populasi terisolasi di Argentina bagian utara.

Deskripsi 

Semua jenis dari marga ini, sesuai dengan namanya, memiliki segmen derik di ekornya yang bisa menghasilkan suara bila digetarkan atau digoyangkan. Namun, ular ini hanya akan menggetarkan ekornya jika merasa terganggu.

Jumlah ruas derik 
Ular derik besar yang baru lahir hanya memiliki satu ruas derik. Ruas tersebut akan bertambah satu setiap ular ini berganti kulit hingga mencapai dewasa. Biasanya ular dewasa memiliki 8 sampai 14 ruas. Namun pernah ditemukan spesimen yang memiliki derik berjumlah hampir 30 ruas.

Spesies 

 Crotalus adamanteus PALISOT DE BEAUVOIS, 1799 - Ular-derik punggung-permata timur
 Crotalus angelensis KLAUBER, 1963
 Crotalus aquilus KLAUBER, 1952
 Crotalus armstrongi CAMPBELL, 1979
 Crotalus atrox BAIRD & GIRARD, 1853 - Ular-derik punggung-permata barat
 Crotalus basiliscus (COPE, 1864)
 Crotalus campbelli BRYSON JR, LINKEM, DORCAS, LATHROP, JONES, ALVARADO-DÍAZ,, GRÜNWALD & MURPHY, 2014
 Crotalus catalinensis CLIFF, 1954
 Crotalus cerastes HALLOWELL, 1854
 Crotalus cerberus (COUES, 1875)
 Crotalus culminatus KLAUBER, 1952
 Crotalus durissus LINNAEUS, 1758 - Cascabel
 Crotalus enyo (COPE, 1861)
 Crotalus ericsmithi CAMPBELL & FLORES-VILLELA, 2008
 Crotalus estebanensis KLAUBER, 1949
 Crotalus horridus LINNAEUS, 1758 - Ular-derik kayu
 Crotalus intermedius TROSCHEL, 1865
 Crotalus lannomi TANNER, 1966
 Crotalus lepidus (KENNICOTT, 1861)
 Crotalus lorenzoensis RADCLIFF & MASLIN, 1975
 Crotalus mitchellii (COPE, 1861)
 Crotalus molossus BAIRD & GIRARD, 1853
 Crotalus morulus KLAUBER, 1952
 Crotalus oreganus HOLBROOK, 1840 - Ular-derik Pasifik
 Crotalus ornatus HALLOWELL, 1854
 Crotalus polisi MEIK, SCHAACK, FLORES-VILLELA & STREICHER, 2018
 Crotalus polystictus (COPE, 1865)
 Crotalus pricei VAN DENBURGH, 1895
 Crotalus pusillus KLAUBER, 1952
 Crotalus pyrrhus (COPE, 1866)
 Crotalus ravus COPE, 1865
 Crotalus ruber COPE, 1892 - Ular-derik punggung-permata merah
 Crotalus scutulatus (KENNICOTT, 1861)
 Crotalus simus LATREILLE, 1801
 Crotalus stejnegeri DUNN, 1919
 Crotalus stephensi KLAUBER, 1930
 Crotalus tancitarensis ALVARADO-DÍAZ & CAMPBELL, 2004
 Crotalus thalassoporus MEIK, SCHAACK, FLORES-VILLELA & STREICHER, 2018
 Crotalus tigris KENNICOTT, 1859 - Ular-derik harimau
 Crotalus tlaloci BRYSON, LINKEM, DORCAS, LATHROP, JONES, ALVARADO-DÍAZ, GRÜNWALD & MURPHY, 2014
 Crotalus totonacus GLOYD & KAUFFELD, 1940
 Crotalus transversus TAYLOR, 1944
 Crotalus triseriatus (WAGLER, 1830)
 Crotalus tzabcan KLAUBER, 1952 - Tzabcan
 Crotalus unicolor VAN LIDTH DE JEUDE, 1887
 Crotalus vegrandis KLAUBER, 1941
 Crotalus viridis (RAFINESQUE, 1818)
 Crotalus willardi MEEK, 1905

Referensi 

 Cope ED. 1867. On the Reptilia and Batrachia of the Sonoran province of the Nearctic region. Proceedings of the Academy of Natural Science of Philadelphia 18: 300-314[310].
 Cope ED. 1883. Notes on the geographical distribution of batrachia and reptilia in western North America. Proceedings of the Academy of Natural Science of Philadelphia 35: 10-35[13].
 Coues E. 1875. Synopsis of the Reptiles and Batrachians of Arizona; with Critical and Field Notes, and an Extensive Synonymy, p. 585-633.[609]. In Wheeler GM. 1875. Report Upon Geographical and Geological Explorations and Surveys West of the One Hundredth Meridian. Volume V. Zoology: Reports Upon the Zoological Collections Obtained from Portions of Nevada, Utah, California, Colorado, New Mexico, and Arizona, During the Years 1871, 1872, 1873, and 1874. Government Printing Office, Washington, DC.
 Fitzinger LJFJ. 1843. Systema Reptilium. Fasciculus primus. Amblyglossae. Braumüller et Seidel, Wien: 106 pp.[29].
 Heckel JO, Sisson DC, Quist CF. 1994. Apparent fatal snakebite in three hawks. Journal of Wildlife Diseases 30(4): 616-619.
 Houttuyn, M. 1764. Natuurlyke historie of uitvoerige beschryving der dieren, planten en mineraalen, volgens het samenstel van den Heer Linnæus. Met naauwkeurige afbeeldingen. Eerste deels, zesde stuk. Dieren van beiderley leven. Amsterdam. 558 pp.[290].
 Hubbs, Brian and Brendan O'Connor. 2012. A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tricolor Books. Tempe, Arizona. 129 pp. ISBN 978-0-9754641-3-7.
 Keegan HL. 1944. Indigo snakes feeding upon poisonous snakes. Copeia 1944(1): 59.
 Klauber LM. 1927. Some observations on the rattlesnakes of the extreme southwest. Bull. Antivenin Inst. Am. 1(1): 7-21.
 Klauber LM. 1936. Key to the rattlesnakes with summary characteristics. Trans. San Diego Soc. Nat. Hist. 8(2): 185-276.
 Klauber LM. 1971. Classification, distribution and biology of the venomous snakes of northern Mexico, the United States and Canada: Crotalus and Sistrurus. pp. 115–156 In Bucherl W, Buckley E. 1971. Venomous animals and their venoms, vol. 2. Venomous vertebrates. Academic Press, New York.
 Klauber LM. 1972. Rattlesnakes: Their habits, life histories, and influence on mankind. 2nd edition. 2 Vols. Berkeley, CA: University of California Press.
 Laurenti JN. 1768. Specimen medicum, exhibens synopsin reptilium emendatum cum experimentis circa Venena et antidota reptilium Austriacorum. J.T. de Trattern, Wien. 214 pp.[92].
 Linnaeus C. 1758. Systema naturae per regna tria naturae secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. 10th ed. Vol. 1. Stockholm. 824 pp.[214].
 Rafinesque CS. 1815. Analyse de la nature ou tableau de l'univers et des corps organisés. Jean Barravecchia, Palermo. 224 pp. (Herpetol. section) pp. 73–78[77].
 Rafinesque CS. 1820. Annals of Nature, or Annual Synopsys of New Genera and Species of Animals and Plants Discovered in North America. Lexington. (22): 1-16.[5].
 Reuss T. 1930. Glasnik Zemaljskog Muzeja u Bosni I Hercegovini. Sveska za Prirodne Nauke. 42: 57-114[60, 88].
 Wagler J. 1830. Natürliches system der amphibien, mit vorangehender classification der Säugthiere und vögel. München, Stuttgart und Tübingen. vi, 354 pp.[176], 9 pls.

 ITIS: Crotalus Linnaeus, 1758
 Crotalus sp. @ Reptile Database
 ADW: Genus Crotalus
 IUCN: Crotalus sp.

Ular berbisa
Viperidae
Reptil Amerika
Fauna Amerika