Interesting Herp Facts

 
Crocodilians 
    Alligators and many turtles share the ability to remain underwater for extended periods of time.  During periods of inactivity these reptiles may remain underwater for hours or even days.  This amazing feat is possible through an intracardiac shunt, which directs blood away from the lungs when the animal is holding its breath.  This mechanism serves a variety of functions in other amphibians and reptiles.  Many terrestrial reptiles such as green iguanas, employ this tactic when they dive underwater to escape predators.  Animals can also employ this strategy when they are not underwater.  When turtles retract into their shells they are unable to ventilate their lungs.  Similarly, a lizard that inflates its lungs to wedge itself into a rock crevice or to make itself appear large and threatening is not breathing. 		 American Alligator  (Alligator mississippiensis) 
 
photo credit: David Scott
 
Salamanders 
    When most people think of salamanders, they think of small animals that are predominantly terrestrial.  However, in order to reproduce, most salamanders must return to the water.  Other salamanders such as those belonging the families Cryptobrachidae, Proteidae, Amphiumidae, and Sirenidae maintain an obligate paedomorphic lifestyle and never leave the water at all.  A paedomorphic salamander is one that achieves sexual maturity while maintaining larval characteristics such as a tail fin and gills.   By maintaining an aquatic lifestyle, salamanders belonging to these families are able to attain great lengths.  In fact, the greater siren (Siren lacertina) and the two-toed amphiuma (Amphinuma means) are both capable of attaining lengths of up to 1 meter.   

    Another impressive fact about salamanders concerns their life spans.  Although one would not expect salamanders to survive for a long period of time, many salamanders can live for up to ten years.  Perhaps the longest  life span of any salamander is that of the hellbender, which can live for anywhere between 25-30 years.  With characteristics such as those described above, it is no wonder that in some forest habitats salamanders make up the largest constituent of the biomass.   

    A little known fact about salamanders is that members belonging to the family Plethodontidae, which is the largest family of salamanders, are completely lungless.  This is an amazing trait considering the fact that Plethodontid salamanders are almost wholly terrestrial.  Instead of using lungs for gas exchange, Plethodontid salamanders respire across their skin.  In order for this strategy to be successful, these salamanders must remain in moist and humid microhabitats.   
 
 

 
 

 Greater Siren  (Siren lacertina) 
 
Photo Credit: JLM Visuals 
  
Blue-Ridge Two-Lined Salamander  (Eurycea wilderae) 
 
Photo Credit: S.G. Tilley
 
 
Lizards 
    Although many amphibians and reptiles are capable of impressive thermoregulatory feats, lizards may exhibit the most impressive thermoregulation of any ectotherm.  Because of their relatively small size, lizards can gain heat via conduction and radiation very quickly.  A species of lizard which lives in the mountains of Peru is particularly effective at both achieving and maintaining a high body temperature.  This lizard is capable of attaining a body temperature of 30o C when the ambient temperature is below Oo C.  Moreover, the lizard is able to achieve this feat in a relatively short amount of time.  
 		 Texas Horned Lizard (Phrynosoma cornutum) 
 
photo credit: Jeff Beane
 
 
Snakes 
    Pit vipers have paired sensory structures known as pit organs located on the sides of the head between the nostril and the eye.  Pit organs are extremely sensitive infrared receptors that convey spatial information about the thermal environment.  These paired structures enable pit vipers to efficiently locate prey even during the night. 

    Another interesting fact about snakes concerns their digestive physiology.  A common characteristic of snakes is that they are able to subsist on large, infrequent meals.  This characteristic is particularly applicable to large-bodied snakes like the eastern diamondback rattlesnake (Crotalus adamanteus), which can endure long intermeal  intervals.  Many snakes are capable of consuming prey items that are up to half of their own body mass.  Others which feed less often, can consume prey that are up to 200 per cent of their own body mass.   

    Perhaps most interesting of all, is the ability of large-bodied snakes to "upregulate" their small intestines in response to feeding.  During the long fasting intervals snakes may shut down their small intestines and related digestive organs to conserve energy.  Once they have acquired a meal, snakes may rebuild their intestine very quickly.  In fact, some snakes can double the size of their intestine within twenty-four hours of feeding. 

 Eastern Diamondback Rattlesnake 
     (Croatulus adamanteus) 
 
                                                  photo credit: Michael Dorcas 
Timber Rattlesnake  (Crotalus horridus) 
 
                                                   photo credit: Michael Dorcas
 
 
Turtles 
    Turtles are unique reptiles in many regards.  Three life history characteristics  in particular set turtles apart from most other reptiles: relatively long life spans; large clutch sizes; and mass nesting migrations.  
  
    Perhaps the best known fact about turtles is that they can live for extended periods of time.  This life history characteristic is essential because some turtles do not reach sexual maturity until they are 15 to 25 years of age.  Large clutch size is another life history characteristic essential to the completion of a turtle's life cycle.  In fact, the green turtle (Chelonia mydas), which returns to the its native shore to breed every few years, can lay clutches of up to one hundred eggs.  In addition, female sea turtles may mate multiple times during a breeding season and lay several clutches.  The large number of eggs laid by mothers is a reproductive strategy which ensures that at least some of their offspring will survive the initial high rate of predation.  

    Another life history characteristic of turtles that is somewhat unique,  is that individuals partake in mass nesting migrations.  Although this behavior is common among amphibians, it is relatively rare in reptiles.  Sea turtles may migrate up to several thousand kilometers from feeding grounds to nesting beaches.  Despite the fact that baby sea turtles are often carried hundreds or even thousands of kilometers from their natal beaches by wind and currents, they manage to find their way home to breed, sometimes 30 to 50 years later.  Scientists believe that sea turtles are able to detect changes in the Earth's magnetic field and that this mechanism allows sea turtles to make the long trip to their natal beaches.   
 

 Green Turtle  (Chelonia mydas) 
 
                                                                   photo credit: Jerry Reynolds 
Loggerhead  (Caretta caretta) 
 
                                                                   photo credit: Michael Dorcas
 
 
Frogs and Toads 
    One may wonder what frogs and toads do when the environmental temperature approaches freezing.  The answer for some amphibians involves burrowing deep into the ground and hibernating.  Hibernating animals are protected from low temperatures, but they are unable to resume activity until spring arrives.  Some toads employ similar strategies to escape the heat.  For instance, spadefoot toads may hibernate during the summer (estivation) or until it rains.  Cases have been documented in which spadefoot toads have remained in estivation for several years and finally emerged to breed upon heavy rainfall.  

    Frogs (along with other amphibians and reptiles) will also hibernate during the winter.  Some frogs even possess antifreeze agents which impart freezing resistance.  These agents prevent water from crystallizing in the cells, which would eventually cause death.

 Eastern Spadefoot  (Scaphiopus holbrookii) 
 
photo credit: Michael Dorcas