Crocodile

1. BY-
SWAYAM PRAKASH NAYAK

2. TAXONOMICAL CLASSIFICATION
Kiingdom-Animalia
Phylum-chordata
Class-reptilia
Super order-crocodylomorpha
Order-crocodilia
 Family-
1. Alligatoridae(alligator & caiman)
2. Crocodylidae(true crocodiles)
3. Gavialydae(gharials)

3. Physiological characteristics
Crocodiles are large reptiles that live throughout the
tropics in Africa, Asia, the Americas and Australia
Exothermic ,so maintain body temp. through
behavioural means
preferred body temperature =30–33 °C

4. The heart rate varies depending on the body
temperature.
10C - 1-8 beats per minute
18C - 15-20 bpm
28C - 24-40bpm
 amphibious reptiles, spending part of their time in
water and part on land.

5.  sexually dimorphic, with males much larger than females
solidly built, elongated, flattened snouts
 laterally compressed tails
 reduced limbs
 front feet - five digits with little or no webbing
hind feet -four webbed digits and a rudimentary fifth.

6. eyes, ears and nostrils of crocodiles are at the top
of the head.
largest species- saltwater crocodile, found in
eastern India
Smallest species-dwarf african crocodile

7. skin -thick and cornified and non-overlapping scales known
as scutes, arranged in regular rows and patterns.
strengthened by bony plates known as osteoderms(back
and neck )
Crocodiles - slender snouts
alligators and caimans - mostly broad ones.
Gharials - extremely elongated.

8. Jaw-
muscles closing the jaws are much more massive
and powerful than the ones that open .

9. Crocodilian teeth - blunt and dull to sharp and needle-
like
teeth of crocodiles and gharials visible than those of
alligators and caimans when the jaws are closed
Only non-mammalian
having tooth sockets
polyphyodonts , replace each of their approximately
80 teeth up to 50 times in their 35 to 75-year lifespan

10. Senses-
 having good night vision and mostly nocturnal hunters
vertical-slit shaped pupils
a nictitating membrane can be drawn over the eye ,
thus protected under the water while a certain degree
of vision is still possible.

11.  ears are adapted for hearing both in air
and underwater
tongue cannot move freely but is held in place
by a folded membrane.
produce vocalisations by vibrating three flaps
in the larynx
sense of smell is also well developed, aiding
them to detect prey or animal carcasses either on
land or in water, from far away.

12. Unlike other reptiles, a crocodile has a cerebral
cortex and a four-chambered heart
Salt glands are present in the tongues of crocodiles
Crocodiles do not have sweat glands and release heat
through their mouths.
 They often sleep with their mouths open and may
pant like a dog

13. Hunting and diet
 ambush predators, good swimmers
eat fish, amphibians, crustaceans, molluscs, birds, rep
-tile and mammals
.

14. slender snouted and fresh water crocodile- fish
eating
Nile crocodile & salt water crocodile-
buffalo,deer,wild boar
 can survive long periods without food
have a very fast strike and are top predators in their
environment
 as opportunistic predators, also prey upon young and
dying elephants and hippos

15.  aggressive scavengers - feed upon carrion and steal
from other predators
 feed by grabbing and holding onto their prey
having sharp teeth for piercing and holding onto flesh,
and powerful muscles to close the jaws and hold them
shut

16.  very fast over short distances, even out of water.
The land speed record for a crocodile is 17 km/h
(11 mph)
may possess a form of homing instinct

17. belly run- body moves in a snake-like fashion, limbs
splayed out to either side paddling away frantically while
the tail whips to and fro. speeds = 10–11 km/h
High walk- holds its legs in a straighter and more
upright position under its body. walkspeed = 5km/h

18. Avg. Life span- 30 to 40 years
Behaviour-
the most social of reptiles
 congregate in certain sections of rivers, during feeding
and basking
saltwater crocodile- highly territorial and aggressive
Social hierarchy-
 the largest and heaviest males having access to the best
basking site
 females are given priority during a group feeding of a big kill or
carcass

19. Vocalization-
Chirp: When about to hatch, the young make a
“peeping” noise, which encourages the female to
excavate the nest.
Distress call: A high-pitched call by younger animals
that alerts other crocodiles to imminent danger
Threat call: A hissing sound as a coughing noise.
Hatching call: Emitted by females when breeding to
alert other crocodiles that she has laid eggs in her nest.
Bellowing: Male crocodile does , when breeding groups
congregate in spring

20. Reproductional behaviour
Penis of male located at cloaca
Copulation takes place in water
Female mates only once a year
Lays hard shelled eggs in a hole or mound nests
Nest is prepared by females along the bank of river,lake
20 to 100 no of oval shaped eggs are laid

21. Avg. Incubation period-80 days
Female remains in the vicinity of nest & helps
emerging young by breaking Upon the eggs
Carry the hatchlings in to water
A group of hatchlings is called a
pod
Sex of the hatchling depends on incubation temp
 Low temp-females
High temp-males

22. Symbiosis between crocodile & plover bird
 Egyptian Plover bird- gets into
the crocodile's mouth and picks
out the tiny bits of food stuck in
his teeth.
 eats them and completes her
diet.
This cleans the crocodile's
teeth and keeps his mouth fresh
and free from infections.

23. HAEMATOLOGICAL PARAMETERS
RBC- 0.9X106uL
Hb- 7.76gdl
PCV- 24.5%
WBC- 11X 103uL
NEUTROPHILLS- 5.9X 103uL
EOSINOPHILLS- 0.95X 103uL
BASOPHILLS- 0.6 X103uL
LYMPHOCYTES- 2.5X 103uL
MONOCYTES- 0.02X 103uL

24. ALLIGATORS
Found in north america & china
2 species e.g 1.american alligator(Alligator
mississippiensis)
2.chinese alligator(A. sinensis)
Wider U shaped snouts
Fourth tooth of lower jaw is inside mouth and not
visible to outside
Hang out in fresh water marshes and lakes

25. CAIMAN
 found inCentral and South America from marshes
and swamps to mangrove rivers and lakes.
have scaly skin and live a fairly nocturnal existence.
The black caiman - largest caiman species in the
world
found in the slow-moving rivers and lakes in the
Amazon basin.

26. Main diet-fish
Predator-jaguar and human
Hunted for skin and meat
Female caimans build a large nest in
which to lay their eggs(10 to 50)

27. GHARIALGAVIAL
SC. NAME-Gavialis gangeticus
Distribution-
Rivers ganga,mahanadi,indus & brahmaputra
Also found in arakan & irrawady rivers of myanmar
Habitat-deep pools at river junction
Features-
Length-12 to 15 feet
Colour-dark olive to brownish olive
Young having greyish brown colour with 5 transverse
bands on body and 9 on the tail

28. Very long & narrow snouts
Jaws armed eith more than 100 teeth
Males developes big outgrowth at tip of its snout,mora
pronounced in breeding season
Called as ghara
Reproduction-
Sexual maturity in males- 13 to 14 yrs
 females- 10 yrs
Mating period- dec & jan.
Females dig nest with her hind legs in a sandy rever
bank
Puts her hind legs inside the nest & start laying eggs

29. Clutch consists of 40 chalky shelled eggs
Incubation temp-32 degree C to 34 degreeC
INCUBATION PERIOD-72 to 94 Days
Weight of young one-75 to 97 g
Basking during winter months is an imp. Behaviour
Life span-29 yrs in captivity

30. MARSH CROCODILEMUGGER
Fresh water crocodile
Sc. Name-Crocodylus palustris
Distribution-india,pakistan,sri lanka,myanmarnepal,iran
Habitat-
River,ponds,lakes
Features-
Length-4m
Weight-200kg
Colour-olive brown with specle of black
Below is white or yellowish
Having broad snouts

31. 4 prominent occipital scales behind head
Back armoured with 16 or 17 transverse and 6
longitudinal bony plates
Webbed toes
Reproduction-
Mating period- january to march
Females lay eggs in hole in sand,gravel on a river,stream
Clutch-3 to 40 no of eggs
Incubation period-60 to 90 days

32. Behaviour-
Excellent swimmer
Habits of basking on river banks
Occassionally roar
In summer months,they aestivate in trasitory waters
Life span-35 years

33. ESTURINE CROCODILESALT WATER
CROCODILE
SC. NAME- crocodylus porusus
Distribution-india,srilanka,thailand,myanmar
In india found in coastal mangroove areas
Habitat-tidal estuaries of marine swamps,coastal
brackish water lakes
Features-
Length-5m
Weight-400kg
Colour-dark olive or brownish olive
Young have black markings above
Longer snout than marsh crocodile
Bony plates- 6 to 8

34. Reproduction-
sexual maturity-8 to 10 yrs
Mating –dry season
Females make nest composed of vegetation and mud
Clutch size-20 to 72 no of eggs
Incubation period-80 to 90 days
Weight of egg- 91 to 137 g
Behaviour-
More aquatic
Very territorial in nature
Large esturine crocodiles are known to be man eaters
sometimes
Life span-35 to 40 yrs

35. AMERICAN CROCODILE-
SC. NAME-Crocodylus acustus
Found in carribean islands and south
florida
 greyish colour and a prominent V-shaped snout.
 Prefers brackish water, exhibits regular sea-going
behaviour Diet -aquatic and terrestrial vertebrates.
 conservation status-
Vulnerable

36. Slender snouted crocodile
 sc. Name-Crocodylus cataphractus
Found in central and western africa
medium sized species with a narrow and elongated
snout.
Lives in freshwater habitats within tropical forests
of the continent.
diet-fish& small to medium sized vertebrates

37. Orinoco crocodile
Sc name-crocodylus intermedius
Found in columbia & venezuela
elongated snout and a pale tan coloration with
scattered dark brown markings.
Diet- variety of vertebrates, including large
mammals.
Conservation status-critically endangered

38. Morelet’s crocodile
Sc. Name-crocodylus morletti
Found in mexico
small to medium sized crocodile with a
rather broad snout
dark greyish-brown colour
freshwater habitats.
Diet- mammals, birds and reptiles.
listed as Least Concern

39. Cuban crocodile
Sc name-crocodylus rhombifer
Found in zapata and swamp of cuba
small but extremely aggressive
prefers freshwater swamps
 the scales have a "pebbled" appearance
 sometimes displays terrestrial hunting.
 snout is broad with a thick upper-jaw and large teeth
sometimes displays pack-hunting
prey - small to medium sized vertebrates.
 Critically Endangered

40. Nile crocodile
Sc name- crocodylus niloticus
Found in sub saharan africa
 large and aggressive species with a broad snout,
especially in older animals.
dark bronze coloration and darkens as the animal
matures. Lives in a variety of freshwater habitats but is
also found in brackish water.
 capable of taking a wide array of African vertebrates,
including large ungulates and other predatorsi
listed as Least Concern

41. Siamese crocodile-
(Crocodylus siamensis)
Small crocodile,prefers freshwater habitats
relatively broad snout and olive-green to dark
green coloration
Found in indonesia

42. Dwarf crocodile (Osteolaemus tetraspis)
 found in western africa
smallest of all living crocodiles.
 heavily armoured species with uniform black
coloration in adults
 juveniles have a lighter brown banding.
 Lives in the tropical forests of Western Africa.
 diet-small vertebrates and large aquatic
invertebrates.
fairly terrestrial species and exhibits terrestrial
hunting, especially at night.
classified as Vulnerable

43. New guinea crocodile
Crocodylus novaeguineae
 grey-brown colour and dark brown
to black markings on the tail.
young have a narrower V-shaped
snout that becomes wider as the
animal matures.
Prefers freshwater habitats, even
though is tolerant to salt water, in
order to avoid competition and
predation by the saltwater crocodile.
 feeds on small to mid-sized
vertebrates.

44. Common diseases
very sensitive to stress
Viral diseaese-
Caiman pox
crocodile pox
adenoviral infection
 Newcastle disease caused by
paramyxovirus
 Eastern encephalitis virus,
 influenza C virus
 coronavirus infections

45. Bacterial diseases
salmonellosis, mycoplasmosis, chlamydiosis,
mycobacteriosis, Erysipelothrix infection, clostridiosis,
dermatophilosis and nonspecific septicaemia
Protozoal infections-
coccidiosis, cryptosporidiosis,
hepatozoonosis, Progarnia sp.
infection, Trichomonas spp., Giardia sp.
and Leishmania sp., trypanosomiasis and infections
by Entamoeba sp. and Blastocystis sp.

46. Parasitic infections
Endoparasites-ascaridoids, capillarioids, trichinellae,
filariae, eustrongylids, rhabditids, hookworms, trematodes
and tapeworm cysts.
 ectoparasites -leeches, biting insects, ticks and mites

47. Crocodile attacks in india
vicious animals known for their ferocious attacks, have attacked
humans for prey across many places in India
Years
August 2010
August 2013
July 2013
Dec 2012