Crocodilians

Question 1

What parenting style do crocodilians have?

Answer 1

Extensive parental care

Question 2

Are crocodiles endo- or ecto- therms?

Answer 2

ectotherms (evolution of endothermy happened between them and birds)

Question 3

How many species of extant crocodile are there?

Answer 3

23

Question 4

Where are most crocodiles found?

Answer 4

tropics or subtropics, but have ranges extending into the temperate zone

Question 5

What are the 3 lineages?

Answer 5

Alligatoridae, Crocodylidae, Gavialidae

Question 6

Where does alligatoridae live?

Answer 6

Freshwater

Question 7

Where does crocodylidae live?

Answer 7

Saltwater, mangrove swamps, lower regions of large rivers

Question 8

How big does a saltwater crocodile grow?

Answer 8

7m

Question 9

What groups are in Alligatoridae include and what is their main characteristic?

Answer 9

Alligators and caimans. Broad-snouted forms with varied diets

Question 10

What is the main characteristic of Crocodylidae?

Answer 10

Range of snout widths, the widest of which are almost as broad as those of Alligatoridae

Question 11

What type of food do broad-snouted crocodiles eat?

Answer 11

Turtles, fishes, terrestrial animals

Question 12

what type of food do narrow-snouted crocodiles eat?

Answer 12

Fish

Question 13

What species does the Gavialidae family contain? What is the main characteristics?

Answer 13

Just one! The gharial. Narrowest snout of any crocodilian

Question 14

How many gharials are left?

Answer 14

Less than 250, making them critically endangered

Question 15

What is the most unique feature of the gharial?

Answer 15

Mandibular symphysis (fusion between the mandibles at the anterior end of the lower jaw) extends back to the level of the 23rd or 24th tooth in the lower jaw

Question 16

How do crocodilians move?

Answer 16

Semi-aqautic, but have well-developed limbs and can make extensive movements on land. Some species can gallop

Question 17

Where do crocodiles hunt?

Answer 17

Water

Question 18

Why are crocodile faces more sensitive than human fingertips?

Answer 18

Upper and lower jaws are covered with small bulges that are insanely sensitive pressure receptors. In complete darkness, alligators can lunge toward a single drop of water

Question 19

What is the main way crocodilians ambush prey?

Answer 19

Wait at water’s edge. After seizing an animal, crocodilian drags it underwater to drown. When prey is dead, it bites off large pieces to swallow whole

Question 20

What are 3 ways crocodilians rip pieces off their prey?

Answer 20

• May wedge prey into tangled branches to hold it steady.
• May use inertia of large prey: rotates when biting (log roll)
• May leave large prey to decompose for a few days before eating

Question 21

What do crocodilians use sound and vocalizations for?

Answer 21

Courtship, territorial displays. Important in dense swamp habitats where territories are often out of sight of other crocodilians. They can roar, males produce subaudible noises.
-hatchlings emit distress squeaks

Question 22

To what extent do crocodilians provide parental care?

Answer 22

Extensive.

• construct elaborate nests w/ large number of eggs (20-70)
• adults protect nest and eggs
• babies vocalize before emerging from eggs, so parents help them out

Question 23

How long do baby crocodilians stay near their mother?

Answer 23

2-3 years. These young feed on small pieces of food dropped by mom, but are not fully dependent on parents for eating.

Question 24

What temperatures determine which sex in all crocodilian species?

Answer 24

Female at low temp, male at high temp. Natural nests are large and have enough variation to produce both

Question 25

Are nests in human structures warmer or colder than those in natural habitats? What does this lead to?

Answer 25

They are warmer in human structures, meaning they produce 100% males