The organ of propulsion for crocodilians is their tail, for swimming, and the
limbs are relatively small. The forelimbs have five fingers, with no webbing
between them. The hindlimbs have four prominent toes and the rudiments of a
fifth. Three of the toes are clawed, with strong webbing between them.
When swimming, the limbs are held against the body, and the swimming action is
an undulating wave from the head to the end of the tail. However, when diving,
the front limbs are lifted up almost vertically, and protrude well above the
level of the shoulder. This is an action that directs the head downward.
The hindlimbs are sometimes used as stabilisers. Crocodilians floating or
swimming very slowly will often have the hind limbs splayed out in the water
with the toes and toe webbing extended. The head is on the surface, but the body
lies almost vertically in the water, with the hind limbs splayed out. An upward
movement of these spread limbs and the crocodile submerges rapidly backwards,
with barely a ripple.
Movement on land is a cumbersome affair. Crocodilians tend to avoid
long-distance movements over land, but occasionally are forced to do so (eg when
waterholes dry up). Some species (eg Australian Freshwater Crocodile, Mugger and
caimans) regularly move overland between drying pools, whereas most species tend
to select habitats where there is deep and permanent water. Crocodilians rapidly
become exhausted when moving on land, and must frequently stop and rest.
"High walking" is the most common gait. The limbs are held erect beneath the
body and the tail drags as the animal walks at about 2-4 km/h. When crocodilians
need to move rapidly on land, usually to get back to the water, they often use a
sprawling gait in which the front and back legs on one side meet when the body
curves in that direction, then separate when the body curves in the other
direction. The tail thrashes from side to side in synchrony with these
movements. When coming down steep, mud banks, crocodiles sometimes just slide,
dragging their limbs, while the tail moves from side to side giving extra
propulsion.
The most spectacular gait is galloping, but few species appear to use it.
Australian Freshwater Crocodiles gallop almost every time they need to move
rapidly on land. Galloping allows animals to jump over rocks and logs between
them and the water. The front limbs go out and forward as the hind limbs propel
the body forward. The tail tends to move up and down rather than from side to
side. Maximum speed attained when galloping is about 18 km/h, although
crocodiles become totally exhausted before they have covered 100 m.
Sources: G. Webb and C. Manolis (1989). “Crocodiles of Australia” (Reed Books:
Sydney);
K. Richardson, G. Webb and C. Manolis (2000). “Crocodiles: Inside and
Out” (Surrey Beatty and Sons: Sydney).
When swimming, the limbs are held against the body, and the swimming action is
an undulating wave from the head to the end of the tail. However, when diving,
the front limbs are lifted up almost vertically, and protrude well above the
level of the shoulder. This is an action that directs the head downward.
The hindlimbs are sometimes used as stabilisers. Crocodilians floating or
swimming very slowly will often have the hind limbs splayed out in the water
with the toes and toe webbing extended. The head is on the surface, but the body
lies almost vertically in the water, with the hind limbs splayed out. An upward
movement of these spread limbs and the crocodile submerges rapidly backwards,
with barely a ripple.
Movement on land is a cumbersome affair. Crocodilians tend to avoid
long-distance movements over land, but occasionally are forced to do so (eg when
waterholes dry up). Some species (eg Australian Freshwater Crocodile, Mugger and
caimans) regularly move overland between drying pools, whereas most species tend
to select habitats where there is deep and permanent water. Crocodilians rapidly
become exhausted when moving on land, and must frequently stop and rest.
"High walking" is the most common gait. The limbs are held erect beneath the
body and the tail drags as the animal walks at about 2-4 km/h. When crocodilians
need to move rapidly on land, usually to get back to the water, they often use a
sprawling gait in which the front and back legs on one side meet when the body
curves in that direction, then separate when the body curves in the other
direction. The tail thrashes from side to side in synchrony with these
movements. When coming down steep, mud banks, crocodiles sometimes just slide,
dragging their limbs, while the tail moves from side to side giving extra
propulsion.
The most spectacular gait is galloping, but few species appear to use it.
Australian Freshwater Crocodiles gallop almost every time they need to move
rapidly on land. Galloping allows animals to jump over rocks and logs between
them and the water. The front limbs go out and forward as the hind limbs propel
the body forward. The tail tends to move up and down rather than from side to
side. Maximum speed attained when galloping is about 18 km/h, although
crocodiles become totally exhausted before they have covered 100 m.
