A reptile's sight

[Smulkin]

I know this is old hat to some of you - but I was curious as to cone/rod distribution in herps' eyes and in the lull that followed that query I did a little poking around:

Snakes have rods and cones in their eyes, as do we, though in different numbers. They do not have the diversity colored oil droplets (presumed to have been lost when snakes when nocturnal and subterranean) in their photoreceptors that mammals and birds do, so, while they do have color vision, it isn't as broad ranged as ours is. They do have a yellow filter which, filling the lens, absorbs ultraviolet light, protecting the eye.

Snakes use a combination of infrared vision (developed in the trigeminal nerve), variable (by species) visual acuity and color detection, limited eye mobility, and chemosensation to find prey and recognize features in their environment (including their keepers).

http://www.anapsid.org/sight.html

Interesting site overall to say the least.

[JLC]

Wasn't "old hat" to me. VERY interesting, Smulkin....thanks!

[Smulkin]

Here's some shtuff on hearing too - more interesting because it contradicts what many of us were led to believe concerning airborne sound waves and snakes' hearing (I take everything with a grain of salt . . . and a wedge of lime) :

Years ago I found a reference to snakes' ability to hear, but, failing to write it down, could never locate it again. Seigel and Collins, in their Snakes: Ecology and Behavior, were not enormously enlightening: "Although there is meager behavioral evidence for hearing of airborne sounds, there is physiological evidence from several species in six families. In addition, attachment of the quadrate to the inner ear suggests that vibrational stimuli could be transmitted by the jaw. However, vibrational cues could just as likely be detected by tangoreceptors on the venter of the snake" (New York: McGraw-Hill, Inc. p. 121, 1993), which most of us already know ('hearing' by feeling vibrations transmitted up from the ground into the belly muscles).

I was pleased to see a short note about snake hearing ability in this month's The Vivarium (6[3]:24-25). In the "Ask the Experts" column, Winston Card responds to a snake hearing question by explaining that, while snakes lack external and middle ear structures (including the tympanum, or ear drum), they do have inner ear structures which have been shown experimentally to receive airborne sound waves.

Thus, like many other animals, snakes have two ways of detecting sounds: earthborne and airborne. The earthborne vibrations are passed through the belly muscles to special receptors along the spine and thus transmitted to the brain. Airborne sounds are transmitted to the lung from the skin receptors to the eighth cranial nerve and inner ear.

Most snakes can hear a person speaking in a normal tone of voice in a quiet room at a distance of about 10 feet (3 m). Two of my snakes have always responded to my calling their names; it's nice to know I wasn't imagining it!

http://www.anapsid.org/snakehearing.html

[iceman25]

Do they have feelings?

[Smulkin]

Tactilely.

[iceman25]

What?

[JLC]

Meaning that have the sense of touch...tactile sensation...they can "feel"... :wink:

[Smulkin]

Only in the "touch" sense of "feeling" - you can't "hurt their feelings" but they can feel physical pain, temperature, texture differences etc.


I died when I read the part on "defensive farts" . . . as a father of three sons I have to validate this as a real and instinctual defensive mechanism among mammals as well.

[iceman25]

Oh ok. LOL Smulkin I think you have one "drunk" online personality :lol:

[JLC]

I died when I read the part on "defensive farts" . . . as a father of three sons I have to validate this as a real and instinctual defensive mechanism among mammals as well.

LMAO!!!!