Crocodiles

Crocodile heart

4 chambered

High pressure of left ventricle sends high pressure oxygenated blood across foramen of panizza so it goes to both systemic arches

Mixing of ventricle blood occurs to ensure entire body gets all available oxygen

Crocodilian characteristics

-Has dermal scutes with osteoderms that provide protection and thermoregulation

-Thecodont (in sockets) dentition

-Polyphyodonty, takes weeks to a year to replace teeth

Gizzards

Organ in digestive tract/stomach, Crocodilian gizzards are often filled with rocks for use in grinding up food (since they cannot chew!)

Half-bound

Small species of crocodiles can do this, more of a gallop

Land movement

Crocodiles are not adept on land, revert to a high walk due to femur. Rarely take prey more than 13ft from water's edge other than foraging on carrion.

Crocodile eyes

Have vertical pupils allows for nocturnal or day vision

Tapetum has guanine crystals that create eyeshine!

Secondary palate

Separates buccal and respiratory passages, allows for breathing while drowning prey.

Crocodile lungs

Well developed alveoli, unique from other reptiles.

Each lung has its own pleural cavity, unique muscles pull liver back which sucks air in. Contraction of abdominal flank muscles increases pressure.

Crocs use a piston pump and a primitive costal aspiration pump

Crocodile senses

Have dome pressure receptors to sense vibrations in water

Have pits for osmoregulatory function.

Salt glands are present in tongues of non-alligatoroids, which explains why crocodiles have wide distributions

Crocodylus porosus

Largest living reptile - the saltwater crocodile

Sex determination

Temperature dependent!

Crocodilian reproduction

Females and some males often protect nests.

Mothers will stay with babies for months to over a year!

Tomistoma

False gharial

Alligatoridea: Alligatoridae

Alligators and caimans

Teeth of lower jaw fit into pits in upper jaw and CANNOT be seen when jaw is closed. Scales on underside of body have no sensory pits.

NO lingual salt glands

Alligatorinae

"True" alligators. TWO species. Both live in areas where seasonal temps drop below freezing!

American alligator

Males are 4m, females are 2.8m

Caiman crocodilus

Common/spectacles caiman. Introduced in FL

Paleosuchus

Dwarf caimans - Leave water at night to forage, diets consist of a lot of terrestrial game! Have dog-like snouts

Crocodyloidea

Notch in upper jaw accomodates 4th tooth of lower jaw. Sensory pits in scales on underside of body.

HAVE salt glands - wide distribution!

Gavialidae

Elongate narrow snouts, narrowest jaws among all crocs. Piscivorous (fish eating). Males have a boss/ghara (pot) when they mature

Crocodylidae

True crocs. 1st mandibular tooth often penetrates the premax. Some have broad snouts while some are slender.

C. johnsoni

Freshwater crocodile. Half-bounds!

C. porosus

Saltwater crocodile. Largest living reptile. 7m, 2000+ lbs.

C. niloticus

Also C. suchus. Nile crocodile! Kills 300-400 people per year

Crocodylus acutus

American crocodile - has a hump in front of eye, lives in costal habitats around rivers and lakes.