Description
Length in wild
- 8-9" at birth
- typical old male 15', female about 10'
- largest recorded in Florida -- 17'5"
Weight in wild
- varies among alligators and is not related to length
- largest males can weigh up to 1,000 pounds
Body
- adults black
- young have vertical yellow bands until about 3-4 years old (see
photo below in "Young")
Tail
- tail equals half total body length
- used for locomotion in the water
- fat stored at the base, so healthy gator has a large, wide base of
tail
Teeth
- 70-80 white, pointed teeth of similar shape
- new ones grow in to replace lost or damaged ones
Lifespan
- about 30-40 years in the wild
- longer in captivity where they don't have to work for a living
Camouflage
- black coloration of adults allows them to stay well hidden in mud (photo
right-- notice the eye at the right center) or shaded and dark water
to await potential prey
- alligators rely on camouflage and stealth to catch prey since they
lack the endurance and stamina to chase prey down in the open
- coloration of young (yellow stripes) helps avoid predators by blending
in with reeds, grasses, fallen sticks at water's edge
|
|
Courtship
- usually begins in early April
- consists of varied sequence of snout-touching, bellowing, coughing,
back-rubbing, circling, bubble-blowing and swimming together
- can last for minutes or hours at a time
- performed over 6-8 week courtship period
|
Breeding
Age
- breed at about 8-10 years in wild, 6 in captivity
Nest (photo at right, female in water at back guarding nest
in foreground)
- made of vegetation, sticks, leaves, and mud dug up by female
- built in a sheltered spot in or near water with mound tall enough that
eggs are above the high water mark
- female builds entire nest mound, then digs down 1-2 feet to lay eggs;
she then lies on top of mound to pack it down on eggs (photo below right,
female packing down nest after turtle dug into it to lay its eggs)
Eggs
- 20-40 goose-egg-sized
- about half hatch
Incubation
- 65 days
- females do not sit on nest except to repair or pack it down
- incubation heat comes from rotting vegetation in nest, like big compost
pile
- sex of young determined in first 3 weeks by temperature inside nest
(above 91° = male, below 85°F = female, between can be either gender,
at extreme low temperatures at bottom of nest usually become males)
- hatching may occur from mid-August to early September
- young begin to make noises -- "chirping" -- from insde egg
and female will dig out eggs to help young to water
Notes
- females responsible for nest and guarding it from other alligators,
especially males including father, and from land predators (raccoons, otters)
- turtles frequently dig into nest to lay their eggs; the threat to the
digging turtle from female alligator is offset by the fact that female
alligator will guard nest from predators that might eat the turtle's eggs
|
|
|
Young
Appearance
- 8-9" in length at birth (one-day old hatchlings in photo above)
- noticeable yellow stripes help them blend into reeds and grasses by
the water to avoid predators
Diet
- live off yolk sack first 2-3 days
- then catch crayfish, snails, insects, aquatic spiders
Protection
- mother alligators very protective of offspring, which may stay
near her for up 2 years (photo right-- mother at top, baby at bottom)
Predation
- young eaten by raccoons, otters, herons, snakes, fish, snapping turtles,
and other alligators
- only about half survive to be one year old, and only about one in twenty
will live to be an adult
|
|
Feeding
Food
- primarily fish (catfish in photo at right), but also insects,
crabs, frogs, snails, turtles, snakes, birds, raccoons, otters, deer, and
smaller alligators
- known to eat already dead animals on occasion
Method
- small prey swallowed whole
- alligator bites down on larger prey repeatedly using combination of
sharp teeth and strong jaw muscles to break bones or shells so the whole
item can be swallowed
- large prey may also be shaken and slapped against water or shore to
rip off swallowing-sized pieces
- alligators roll under water with very large prey, submerging victim
and drowning it
- dead prey dragged around or guarded until meat rots enough so it's
soft enough to be ripped apart and swallowed
Frequency
- little energy spent maintaining high body temperature since it's cold-blooded,
and therefore needs less food
- healthy alligators can go many months without food
- feed most often when temperatures between 73-90°F
- Note: Red-bellied Turtle in photo at right survived this encounter.
When the alligator tongued it to the side to crush the shell in its teeth,
it opened its jaws too much and the turtle popped out and quickly swam
away. Scratches frequently seen on turtle shells are reminders of similar
encounters.
|
|
Locomotion
In water
- tuck legs close to sides and propel bodies forward with sidestrokes
of tails
- webbed hind feet act as paddles and brakes while tail is motor and
rudder
- cruise through water at just over 1 mph; in pursuit of prey can swim
much faster over short distances
- powerful tails enable them to hydroplane at surface or leap and lunge
out of water up to five feet in air with incredible speed
On land
- can lumber along dragging tail, or can walk on toes with heels of hind
feet and most of tail well off the ground
- using this "high walk," alligators can run up to 30 mph for
very short distances, but they only run in a straight line and they have
no endurance
- when moving from one body of water to another, alligators frequently
use common paths in the mud, called "slides," where it takes
less energy to pull their bodies through the mud than to walk over dry
land (photo at right)
|
 |
Range
- Found throughout the Southeast in the coastal swamps from the Carolinas
around the coast to Texas and as far north as Arkansas in coastal flatlands
- prefer fresh water but can tolerate some brackish water
|
Senses
- physical stimulation from environment triggers senses of touch, sight,
hearing;
- chemical signals trigger taste and smell
- sides of head loaded with sensitive touch receptors
- sensitive lip scales enable gator to detect movement and vibration
from potential prey, mates, territorial rivals, and approaching predators
- well-developed sense of smell used to detect prey and identify potential
mates
- have acute sense of hearing and always on alert for prey-like sounds,
especially when hungry
- show unmistakable response to faintest vibrations produced when small
animal jumps into their water
|
 Alligators have
thousands of small nodules sprinkled across their faces that are very sensitive
pressure detectors. Up close, they look like little bumps about the size
of ball point pen tips, and are most noticeable around the edges of the
mouth. These allow the alligator to "sense" presence, size, movement,
and location of other animals in the water around it.
This is a tremendous advantage for a creature that primarily hunts at
night or in dark and murky water.
Alligators are especially tuned in to splashing in the water, frequently
caused by an animal in distress, two animals fighting or playing in shallow
water, something walking along the edge of the water, or even a bird or
animal bathing. All indicate prey that may not be paying as close attention
as it might otherwise be to its surroundings. |
Cold Blood
- all activity - feeding, metabolic rate and even digestion - is dependent
on external temperature (feeding behavior ceases when water temperatures
drop below about 60°F)
- heat from sun activates digestive enzymess, so cold temperatures can
kill a gator with a full stomach because the food will rot instead of digest
- optimum body temperature is around 89°F; when air/water temperatures
cool, alligators crawl out of the water to warm in the sun where their
dark skin absorbs the heat, and when they are too warm, they return to
the water to cool off; on cool windy days or hot summer days, they remain
in the water
|
Submerging
Preparation
- like a submarine preparing to dive, alligators also close hatches:
a semitransparent membrane or third eyelid called the nictitating membrane
covers eyes; folds of skin close over the ears; muscles contract sealing
the nostrils shut; and throat closes tight, enabling it to open its mouth
to catch and hold prey underwater without drowning
Time under water
- several hours if not actively swimming or hunting (then it's only about
20 minutes); they do this by rerouting blood to reduce circulation to the
lungs, and thus the need for oxygen
Economy
- wasted motion in water or on land is unknown;
- immobility allows them to conserve metabolically (and remain unobtrusive
in case anything good to eat wanders too closely).
- Biological explanation: When alligators hold their breath, carbon
dioxide builds up in their blood, dissolves, and forms bicarbonate ions.
The ions bind to amino acids in the hemoglobin. Once bound, the ions cause
the oxygen-carrying hemoglobin to release additional oxygen molecules into
the blood system, increasing the amount of oxygen available to the reptile's
body tissues
|
Mouth
Teeth
- roughly 20 pairs of inch-long replaceable teeth on each jaw
- used for seizing, holding, and crushing prey
- hollow and conical-shaped
- new teeth interstacked below gum line and continuously push up from
sockets to replace worn teeth or those broken off in combat or biting on
hard objects
Size
- can entirely engulf small water creature or leap out of water to grab
leg or snout of larger prey
- light colored skin along jaw line only highlights about two-thirds
of mouth (actual mouth extends well past eyes to base of neck)
Jaws
- powerful muscles slam jaws shut with force estimated up to 2,000 pounds
per square inch
- once closed, jaws cannot be forced open (only punch to sensitive snout
or poke in eye might startle them enough to release grip)
|
 |
Communication
 Alligators use
visual, aural, tactile, and olfactory cues. Complex body postures and movements
communicate a variety of information. Both sexes give off musk. Even though
they have no vocal chords, alligators hiss, grunt, cough, growl, and bellow.
To listen to alligator sounds, visit the Florida Museum of Natural History
crocodilian
communication page.
Hiss
- long, loud, full-bodied hiss is defensive warning
- typically produced just prior to defensive attack
Bellow
- bellowing choruses occur most often in spring when breeding groups
congregate, but can occur at any time of year
- repeated calls carry great distances around water
- females also produce single characteristic bellow-growl when approached
by male
- tone and intensity of bellow influenced by body size, gender, and individualized
differences in calling patterns
- to bellow, male noticeably inflates as he raises tail and head out
of water; slowly waving tail back and forth, he puffs out throat (photo
above), and with closed mouth begins to vibrate air; just before bellowing,
males project an infrasonic signal at about 10 Hz through water that vibrates
ground and nearby objects; the low-frequency vibrations travel great distances
through both air and water to advertise caller's presence; vibrations are
so strong they literally make the water "dance"
- male alligators use "water dance" to woo females and to signal
location and dominance among other males
- will bellow to sonic booms and thunder as well as other alligators
|
Vision
 At night
- with the pupils fully dilated, sharpness of vision comparable to an
owl's
- like cats, alligators have thin layer of special reflecting tissue
behind each retina called tapetum lucidum (bright carpet) which
acts like a mirror to concentrate all available light during darkest of
nights (a definite advantage for a night-active meat-eater)
- also causes coal-red eyeshine at night when caught in the flashlight
beam
Peripheral
- bulging eyes on top of head provide 25 degrees of binocular vision
to judge distance and attack with accuracy
Protection
- can pull soft eye orbits down into skulls, letting them pop back up
when coast is clear
- before eyes closed, nictitating membranes close front to back, then
eyelids close top to bottom
Eye rotation
- like a compass needle pointing perpetually north, oval-shaped pupils
remain vertical to horizon, even when head tilted
- adaptation for enhanced, undisrupted vision possible by compass-like
movement of eyeballs (but it only works when somewhat horizontal. Flip
a gator on its back and visual system and equilibrium disturbed- eyes unable
to focus and gator motionless as though experiencing extreme vertigo)
|
