have three eyelids, with the third being referred to as the nictating membrane
cleans the eye on land, and protect the eye whilst underwater
osteoderms covered in thick keratinous skin provide armour to the neck, trunk, and tail
crocodilian hearts possess four-chambers
completely divided ventricle with two pumping chambers
lung circulation and body circulation are separated
foramen of panizza allows the mixing of blood from outside the ventricles
allows for enhanced oxygen transport whilst underwater
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Crocodylia Reproduction
all crocodilians are oviparous, with clutches averaged between 12 and 48 eggs
clutch size increases with female size both between species and within species
all crocodilians use internal fertilisation
all crocodilians use temperature-based sex determination
two types used in Crocodylia: type 1b and type 2
eggs deposited either in mounds, on floating vegetation in shallow water, or in burrows
all crocodilians display parental care, but the level varies
common trait among archosaurs
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Crocodylia Lifespan
can live long periods (up to 120 years), but do stop growing
lose their power in old age like other animals, so not immortal as some reports claim
can repair parts of their body, e.g., their tail
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Ecology & Behaviour of Crocodylia
predators that ambush prey in shallow waters or at waterside
semiaquatic and spend much of their life in the water, but do spend time out of the water
regularly bask on the shoreline
construct territorial nests for incubation of eggs
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Crocodylia Diversity
GAVIALIDAE: a family containing the Indian gharial and the false/Malayan gharial
contains two species in two genera
genera split 20 million years ago
CROCODYLIDAE: a family of crocodilians in which the fourth tooth of the lower jaw fits into a notch in the upper jaw, being visible when the mouth is closed
CROCODYLINAE: subfamily of true crocodiles, containing all species except the dwarf and slender-snouted crocodiles
OSTEOLAEMINAE: subfamily of true crocodiles, containing the dwarf and slender-snouted crocodiles
ALLIGATORIDAE: family of crocodilians that have a broad, flat snout in which the fourth tooth of the lower jaw fits into a pit in the upper jaw and cannot be seen when the mouth is closed
ALLIGATORINAE: subfamily of Alligatoridae which contains the alligators and their closest extinct relatives, consisting of one genus (Alligator)
CAIMANINAE: subfamily of Alligatoridae which contains the caimans and their closest extinct relatives,consisting of three genera
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Crocodylia Conservation
status reports show that crocodilians are in serious decline globally
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