Snakes
External Anatomy
no limbs
nostrils
no external ears
no eyelids
scales - of various size depending on body location
(for ID - "keeled" or not keeled)
anal shield - denotes boundary of trunk & tail
(for ID - anal plate divided or not)
Internal Anatomy
only one lung
no urinary bladder
many vertebrae/ribs
no sternum (breastbone)
very linear digestive tract
Snakes exhibit the concept of "Reduction"
they have lost several anatomical
features typical
to other vertebrates:
no ears
no urinary bladder
no limbs
no left lung
no sternum
Senses
vision - poor
hearing - poor
smell - excellent
forked tongue - Jacobson's organs (roof of mouth)
heat - some snakes can detect body heat = "Pit Vipers"
they have pits or holes around mouth that sense
IR (body heat) (warm blooded prey)
Killing their food:
(all snakes are carnivorous)
1. catch & swallow (garter snake, hognose)
2. squeeze to death "asphyxiate" the constrictors
(boas, pythons, kingsnakes)
3. poison & swallow (rattlesnake, cobra)
Poisonous Snakes:
cobras, coral snake, sea snakes …….
types of venom:
neurotoxin
hemotoxin
snake bite? antivenom shot
Illinois' Poisonous snakes:
Water Moccasin (Cottonmouth)
Copperhead
Timber Rattlesnake
Pygmy Rattlesnake
(swamp rattler or massasagua)
Cottonmouth
Timber Rattlesnake
Copperhead
Practice Quiz: Snakes
Skull Adaptations - snakes have a
very movable or "Kinetic" jaw
jaw bones unhinge and drop
front ligament - R/L halves
thrust forward independently
teeth slant backwards
Birthing
Oviparous - lay eggs (most snakes)
Ovoviviparous - retain eggs in body - attached to yolk sac
Viviparous - live birth
Largest Snake ever officially recorded:
an Anaconda, captured & measured in 1944
South America - Orinoco River
37 1/2 feet!
estimated to weigh nearly 600 pounds!
Illinois Non-Venomous Snakes
Garter Snake
DeKay’s
Brown Snake
Northern Water
Snake
Black Rat Snake
Prairie King Snake
Western Hognose Snake
Practice Quiz – Ill. Non Venomous Snakes