SerpentesSerpentes

TitanoboaTitanoboa• Some 60 million years ago, well after the demise of the dinosaurs, a

giant relative of today's boa constrictors, weighing more than a ton and measuring 13 meters long, hunted crocodiles in rain-washed tropical forests in northern South America, according to a new f il difossil discovery.

• The fossil find - a batch of super-size vertebrae pulled from an open-pit coal mine in northeastern Colombia - is remarkable enough just

l t l i l t Th i i thas a paleontological extreme. The species, given the name Titanoboa cerrejonensis, is the largest known snake species ever discovered.

LocomotionLocomotion

• Figure 13-5Figure 13 5– Lateral undulation http://www.youtube.com/watch?v=JA5PyUFGHtI

Rectilinear– Rectilinearhttp://www.youtube.com/watch?v=Ci_OxulaWwY

– ConcertinaSidewinding– Sidewinding http://www.youtube.com/watch?v=JyXNBAHu32o

Snake SkullSnake Skull

• Snakes have 8 links in the skull with jointsSnakes have 8 links in the skull with joints

Prey detectionPrey detection

Thermal prey detectionThermal prey detection

• Some snakes detect prey by thermal cuesSome snakes detect prey by thermal cues• Infrared light is sensed by trigeminal-

innervated blind nerve endingsinnervated blind nerve endings• Many boas and pythons have labial “pits”

d t li ( it i ) h “ it ” iand crotalines (pit vipers) have “pits” in their loreal scales

• Temperatures of 0.05 degrees C will elicit a response from some snakes

Prey capturePrey capture

• Depends on prey many species just grabDepends on prey, many species just grab their prey and eat it.

• Large prey pose other problems• Large prey pose other problems• Constriction http://www.youtube.com/watch?v=-Evvo79ojME

• Venom injection http://www.youtube.com/watch?v=_wSetsdtNfw

Venomous snakesVenomous snakes

• Venom glands are Duvernoy’s GlandVenom glands are Duvernoy s Gland• The venom delivery system consists of the

gland muscles to force venom from thegland, muscles to force venom from the gland, ducts to transport venom, and fangs to inject venomto inject venom

Venomous snakesVenomous snakes• Opisthoglyphous – snakes have one or more p g yp

enlarged teeth near the rear of the maxilla (mainly found in Colubrids)P l h h ll f l d h• Proteroglyphous – hollow fangs located at the front of the maxilla that are permanently erect (Elapidae)(Elapidae)

• Solenoglyphous – the hollow fangs are the only teeth on the maxilla and can rotate so that the fangs can fold up when the mouth is closed (pit vipers and true vipers)

VenomVenom

Table 13-4Table 13 4

Snake defensive behaviorsSnake defensive behaviors• Death feigningg g• Mimicry• Warning colorsg• Diverting attack• Spitting

• http://www youtube com/watc• http://www.youtube.com/watch?v=_5dtpMj9Ehs