They are possibly most closely related to obscure South American "groundsnakes" in the genus Psomophis, or to the even more obscure genus Saphenophis, which was described by Myers as "quite lacking in peculiar or unique features" and so named "in allusion to one incontrovertible fact about these om the Greek saphenes (evident truth, clear) + ophis (a serpent), meaning 'clearly a snake'". Beyond that, there isn't a lot of clarity about their next-closest relatives.
occidentalis is Pseudalsophis elegans, the only species in the genus found on the mainland (in Ecuador, Peru, and extreme northern Chile). It seems pretty clear that the nearest relative of P. In 1973, herpetologist Charles Myers wrote: "The classification of colubrid snakes in general, and of South American colubrids in particular, is in a notoriously unsatisfactory state." Unfortunately, we are not that much better off today when it comes to Galápagos Racers. They have been in a variety of genera since their description, especially Dromicus, which is no longer in use, from 1876 to 1997. And, baby Galápagos marine iguanas that hung around their hatching area had about a 10% lower survival rate than those that moved to the coast, which the researchers attribute mostly to higher risk of predation at the nesting area.īroadly, Pseudalsophis is nested within a large clade of Caribbean, Central, and South American xenodontine snakes including, among numerous others, the genus Alsophis, which once contained Galápagos Racers and after which their current genus is named. Another study of Galápagos land iguanas showed that predation attempts by Galápagos hawks were more than three times as likely to be successful when the body temperature of the iguana hatchlings was below 90☏. They estimated that about 20-30% of hatchling iguanas survived their first month, and those that moved quickly and linearly away from their nests were the most likely to survive, perhaps because predators had learned to hang around the nesting area. In a study of Bahamian rock iguanas ( Cyclura cychlura), snake predation was the most likely cause of mortality for newborn iguanas dispersing away from their nests. Female Marine Iguanas may all use the same nesting sites because those are the only sites available, or they may choose to nest near one another because, just like with sea turtles, synchronous hatching of the young increases their probability of survival. Many species of reptiles nest in areas where they otherwise do not spend much time, especially aquatic species ( reptile eggs need to "breathe" air and cannot be laid underwater). One estimate suggested that the cost of migrating to their nesting sites represented half the reproductive effort of female Galápagos land iguanas. They choose protected lava reefs for this purpose, which are in short supply on most islands. Marine Iguanas have to dig nests and lay their eggs in soft sand, away from the rocky, tidal foraging grounds of the adults. Depending on which sources you consult, there are between 4 and 7 species of Pseudalsophis in the Galápagos, as well as one in mainland South America.įates of rock iguana hatchlings, over half of which wereĮaten by Cubophis and Epicrates snake predators in theirįirst month of life. Galápagos Racers belong to the genus Pseudalsophis. Although these snakes are called "racers", they're not closely related to North American racers (genus Coluber) it's been about 45 million years since these two snakes last shared a common ancestor. Throughout the clip, Attenborough calls them "racer snakes" 1, but herpetologists would normally call the snakes on the screen Galápagos Racers.
#Lots of snakes chasing a lizzard free#
If you have one that isn't listed, feel free to ask it in the comments! And, if you want to know more about the process I used to dig up some of this information, check out my tutorial for teaching oneself about obscure snakes. For a few days after it aired, the Internet was buzzing with these questions, and I've cataloged the answers to some of the most popular ones below. In addition to being a highly dramatic cinematographic masterpiece, it raises a number of interesting questions about the biology of the snakes in the clip. If you haven't seen the incredible footage of the "iguana chase scene" from the BBC's Planet Earth II Islands episode, I encourage you to watch it right away.
On Fernandina Island, from the BBC's Planet Earth II footage Galápagos Racers ( Pseudalsophis occidentalis)
0 kommentar(er)
