Diamondback Rattlesnake


I almost stepped on this very large Eastern Diamondback Rattlesnake (Crotalus adamanteus).  The snake was coiled between two of my ponds and had apparently been feeding as she was moving slowly and had a large bulge in her belly.  I estimated her length between 6 and 7 feet (1.8 to 2.1 m).

The weather was extremely warm and dry, which brings these reptiles out of their burrows.  On this day the temperatures topped out in the low 90°s F (32° C) across Central Florida.


I stayed a good distance from the snake and made these images with a 300 mm lens (12 inch).  The snake senses heat and though the day was warm my body temperature was warmer than the air.  Once she saw that I was a threat she started retreating while coiling and never taking her eyes off of me.



The eastern diamondback is the largest rattlesnake species and the heaviest venomous snake.  The heaviest known specimen measured 7.8 feet (2.4 m) in length and weighed 15.4 kg (34 pounds).  The maximum reported lengths are in the range of 8 to 8¼ feet (2.4 - 2.5 m).


 The magnificent scales of this snake include 25-31 (usually 29) rows of dorsal scales mid-body, 165-176/170-187 ventral scales in males/females and 27-33/20-26 subcaudal scales in males/females.  On the head the rostral scale is higher than it is wide and contacts two inter-nasal scales.

 
Above:  The long lens on the camera distorts the snakes length in this photo.

The snake's excellent camouflage consists of a brownish, brownish yellow, brownish gray or olive ground color, overlaid with a series of 24-35 dark brown to black diamonds with slightly lighter centers.  Each of the diamond-shaped blotches is outlined with a row of cream or yellowish scales.  I counted at least 27 diamonds on this mature individual.

Below:  I tried to get some of the background (the garage) in the photo for scale.  From a distance, stretched out, she almost looked like one of the infamous, large Burmese Pythons that have moved into this part of Florida, but her diamond shaped head, markings, and rattles identified her as the more elusive and dangerous Diamondback Rattlesnake.


These snakes frequently live in mammal and gopher tortoise burrows, emerging in the early morning or afternoon to bask.  We have two large tortoise burrows in the earthen-floored garage.  The snake did not head for the garage, however, it choose shelter instead in a large pile of debris we have in an old sinkhole at the back of the property.

This species eats mostly rats and cottontail rabbits, of which we have no shortage.  They are too large to bother with lizards or other smaller prey.


The Eastern Diamondback Rattlesnake is known as the most dangerous venomous snake in North America.  While not usually aggressive, they are large and powerful.  The mortality rate of humans bitten has been reported to be between 10 and 30%.

In proportion to its length, it has the longest fangs of any rattlesnake species, with calculations leading one to expect an 8-foot (2.4 m) specimen would have fangs with a total length of over 1 inch (25 mm).

The venom contains a thrombin-like enzyme called "crotalase," that is capable of causing high hemorrhagic activity.  In theory the venom also leads to cardiac failure due to the presence of a low-molecular-weight basic peptide that impedes neuromuscular transmission.


The snake elicited a visceral response in me.  I immediately stopped, backed up, and then carefully fled.  My heart rate noticeably elevated.  My eyes grew tight.  My mind raced.   The physical responses I felt can only be explained by millennia of evolution, as typically one would stop to admire a creature of such beauty that is so rarely seen up close.  While this is not my first close encounter with an Eastern Diamondback Rattlesnake it was my largest encounter ever.

In 2008 and 2012 I encountered much smaller individuals in the same general area where this snake was located (see my photos here).
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