Alligators, Crocodiles, and Hippo’s

What is this?

What is this?

• Caiman

Which one is which?

Crocodilians

• Alligators, caimans, crocodiles and gharails are jointly referred to as CROCODILIANS

Crocodilians

Crocodilians

– About 20 species of crocodilians all of which are lizard like, egg laying, eat eaters

– Largest modern reptiles they constitute the last living link with the dinosaur like reptiles of prehistoric times

– Live in water but also travel on land by sliding on their bellies, stepping along with their legs extended or galloping awkwardly

Crocodilians–

Large adults can stay under water for over an hour without breathing

– Swim primarily by snakelike movements of their bodies and by powerful strokes of their muscular oar like tails (also acts as a weapon)

– When float in water they leave only their nostrils, eyes, and ears above the surface. Eyes can be covered with semitransparent membranes and the ears and eyes are closed over by folds of skin

Crocodilians

They control the depths at which they float by controlling the amount of air they retain in their bodies

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American Alligator

American AlligatorsPhysical Traits

• Belongs to the family Alligatoridae• American Alligator (Alligator mississipiensis)

inhabits the Southeastern United States from North Carolina to Florida and west to the lower Rio Grande.

• Chinese Alligator (Alligator sinensis) is found in the Yangtze River Valley of China

American AlligatorPhysical Traits

• Inhabit large shallow lakes, marshes, ponds, swamps, rivers, creeks, and canals in fresh and brackish water area

American Alligator Physical Traits

• Elongated armored, lizard-like bodies with muscular flat tails

• Broad head with a long, wide, rounded, shovel-shaped snout (shorter than a crocodile). Nostrils at the end to allow breathing while submerged under water.

Alligators Physical Traits

• Their eyes and nostrils close by reflex when the animal goes underwater.

• They have a transparent third eyelid, or nictitating membrane, that covers the eye as the animal moves through the water.

• Valves to close the ears and nostrils when it is submerged

Alligator Look at Nose, Eyes, and Ears

Alligators Physical Traits

• Four short legs – five toes on the front feet and four on the rear

• Skin on their backs is armored with rows of bony plates called osteoderms or scutes

• Average adult size – 8.2 feet for females and 11.2 feet for males

• Can weigh more than one ton

Alligators Physical TraitsHow many toes?

Alligator Traits

• Young hatchlings have bright yellow stripes and blotches

American AlligatorPhysical Traits

• Adults are dark with pale undersides• Do not have a tooth that shows outside of

the mouth when closed• Poikilothermic or ectothermic having an

internal temperature similar to their surroundings (formally called cold blooded}

AlligatorsFeeding Habitats

• Alligators are carnivores• Young alligators eat insects, snails, frogs, small

fish, and invertebrates.• At a length of 6 feet they feed mainly on fish,

turtles, snakes, water birds and small mammals.• An adult will eat 20 lbs per week in hot weather,

but no food during the winter.• Large alligators readily eat carrion (dead flesh)

and in fact prefer it to fresh meat.

Alligator eating a turtle.

AlligatorsFeeding Habitats

• They are opportunistic feeders and will eat almost anything including such objects as sticks, stones, fishing lures, and aluminum cans

AlligatorsReproduction

• Sexual maturity depends on the size of the alligator – about 6 feet. Wild alligators will be about 10-12 years old. For alligators raised in captivity it will be much sooner

• Mature alligators seek open water areas in April and May – courtship and breeding season

• Males roar during the mating season, but the normal vocalization is a hiss.

Alligators Mating


• After mating females move into marsh areas to nest in June and early July

• Females construct mounded nests of available vegetation. They lay between 35-50 eggs (There may be as few as 1 or as many as 88)

• After laying eggs the female covers the eggs with a layer of vegetation


• There is a 65-day incubation period. Females stay nearby their nests and defend their eggs against predators such as raccoons. Only fifty percent of the eggs will survive.

• Females are territorial and will guard and defend their nests.


• Eggs hatch in mid August – mid September. The young alligators make high-pitched grunting sounds from within the egg. Females respond by using their mouths to remove the nesting materials covering the young thus liberating 6-8 inch hatchlings


• Hatchlings remain in groups called pods at least through the first winter and may stay near the nest site for 2-3 years

• First 2 years of life is the most critical. Birds, raccoons, bobcats, otters, snakes, large bass or even large alligators may eat 80 % of the hatchlings


• Once an alligator exceeds 4 feet it is relatively safe from predators but is still vulnerable to cannibalism

AlligatorBehavior

• Are apex predators• Thermoregulate – sun themselves during the

day and go into the water at night• Lead solitary lives establishing individual

territories

Alligators and Humans

• Alligators have been hunted for meat and skins (Handbags, luggage, shoes, belts, etc.)

• Today through strict laws alligators may be harvested during very limited controlled hunts and are raised in captivity for the production of meat and skins

Alligators and Humans

• Urbanization in Florida has increased the contact between alligators and humans (For example they are found in pools, on golf courses, ditches, etc.)

• Risk of being attacked is low (especially 4 feet or less, over 6 feet is a greater hazard)

• Most attacks occur because humans feed alligators or when they are defending their nests

Solutions

• DON’T swim outside of posted swimming areas in water that might contain large alligators. DO swim in designated areas only

• DON’T swim at night or dusk when alligators most actively feed. DO swim during the day and avoid areas of thick vegetation near the shoreline

Solutions

• DON’T feed alligators. They lose their natural shyness and become attracted to humans when fed

Solutions

• DON’T throw fish scraps into the water or leave them on the shore. DO dispose of scraps properly

• DON’T allow pets to swim near waters known to contain large alligators

• DO report nuisance alligators (more than 4 feet in length that appear to have lost their natural fear of people or otherwise pose a threat to people or property) to the Florida Game and Fresh Water Fish Commission

Legal Aspects

• American alligators are listed by the state of Florida as species of concern and by the Federal Government as threatened due to the similarity in appearance to the endangered American Crocodile

• It is illegal to feed, tease, harass, molest, capture or kill alligators

• The Florida Game and Fresh Water Fish Commission strictly regulate an alligator management program

American Crocodile

American Crocodile

• Scientific Name and Range– Crocodylus actus

Found in coastal wetlands along the Pacific Ocean from Western Mexico south to Ecuador and along the Atlantic Ocean from Guatemala north to the extreme tip of Florida

America CrocodileHabitat

• Tropical wetlands and freshwater rivers• Mangrove-lined saltwater estuaries. Adults

can survive in salt water but babies can not• Not considered a marine animal but have

been found to travel hundreds of miles across the ocean to reach some isolated volcanic islands

Mangroves

American CrocodilePhysical Description

• Adult crocodiles range from 7 to 30 feet long (larger than the alligator)

• Snout is longer and more pointed than alligators

• Fourth tooth on each side of the lower jaw is always visible. Teeth are used for seizing and holding prey not chewing. Replaced continuously (as new ones grow up, force old ones out

Crocodile’s Tooth or Teeth Showwhen mouth is closed

American CrocodileFeeding Habits

• Carnivores• Feeds largely on fish and other small marine

life• Larger ones may also feed on small mammals,

birds and turtles• In Florida, known to eat bass, tarpon and

mullet

American CrocodileReproduction

• Male and females mate with several partners during their mating period

• Females lay as many as 40 eggs. Females build mound nests of soil and sand. Some build hole nests. Eggs are warmed by the sun


• Only 50 % of the eggs will hatch• Only 10 % of those that hatch will survive the

first year

Crocodiles and Humans

• More likely to attack than alligators (alligators will usually attack only when cornered)

• More ferocious than alligators• Ancient Egyptians considered the crocodile a

symbol of the Gods and it is still regarded as sacred by some groups in Pakistan

• Crocodile hides have been used to make belts and handbags

Crocodile Handbags and shoes

• $4,300.00 $291.00

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Legal Aspects

• Proclaimed endangered on Dec. 18th, 1979 because of habitat loss and hide hunting

• As hide hunting has been eliminated the American Crocodile has responded to recovery operations and is on the increase. Lives today mainly in tidal marshes in the Everglades along Florida Bay and in the Florida keys

• Today most crocodile deaths are due to accidents with cars and boats

Comparison

Similarities

• Belong to same order Crocodilia• Predators• Poikilothermic• Carnivores

Differences

• Alligators do not have a tooth that shows outside of the mouth when it is closed, while crocodiles DO have such a tooth

• Snout of an alligator is very short and wide. Snout of a crocodile tends to be longer and more pointed

• Crocodiles are generally much larger than alligators and much more ferocious

Hippopotamus

•Hippopotamus

Hippopotamus

• Belongs to the family Hippopotamidae• Hippopotamus (river horse) is amphibious

(living on both land and water)• Formerly found throughout all sub-Saharan

Africa, but presently found by the Nile River valley of East Africa

HippopotamusHabitat

• Rivers and lakes throughout West and East Central Africa

• Deep water with adjacent reed beds and grasslands

HippopotamusPhysical Description

• Massive animal males can get 12 feet long and 5 feet high, weighing 8000 pounds. Females slightly smaller

• Body brownish gray on top, and paler on the underside, with pink areas on the face

• Eyes, ears, and nose are high on the head to allow the animal to be almost totally submerged. Facial features resemble a pig

Hippo eyes, ears, and nose position

HippopotamusPhysical Traits

• They were once thought to sweat blood. Actually they secrete a pinkish colored oil that helps keep their skin moist in the hot African climate and may act as sunscreen, and an antiseptic

• Short legs• Second largest land mammal

HippopotamusFeeding Habits

• Strictly a vegetarian – eats soft, short grass and other plants, including fallen fruits

• Efficient grazers – lips almost two feet wide• Spend most of their days in the water or

wallowing in the mud, generally coming up on land to feed at night

HippopotamusReproduction

• Capable of breeding year round, but peaks during February and August. Males reach sexual maturity (in the wild) between 6-14 years old, while females are capable of breeding between 7-15 years

• Birth of young coincides with periods of peak rainfall in October and April


• The female usually experiences a three day period when she is mated by the resident bull

• Gestation period is about 230 days or 8 months (Humans is 270)

• Cow gives birth to one young calf born at a time weighing about 50-100 pounds. Calves nurse underwater and will ride on their mother’s back in the water


• Baby swims the moment it is born because it is born underwater

HippopotamusBehavior

• Sleeps during the day, active at night (not strictly nocturnal)

• Graceful in water, their specific gravity allows them to sink to the bottom of rivers where they can walk or run

• Live in family groups called herds which consist of up to 30 animals including one male, several females and their offspring

HippopotamusBehavior

• Aggression between males is intense using long canine teeth as weapons. Death often occurs. Losing males live alone

a.Aggression between males is intense. Use long canine teeth as weapons, and death often results. Losing males often live alone.

HippopotamusEconomic Importance (positive)

• Food source for people of Africa• Teeth are used for ivory• Hide is valuable – used for shields and whips

Teeth used for ivory

HippopotamusEconomic Importance (negative)

• Raid agricultural crops – hurts the economy• Very aggressive and have little to no fear of

humans• One of the most dangerous of Africa’s animals

Alligators, Crocodiles, and Hippo’s

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