By Nikoma Boice
Geographic Range
This species of crocodile is found in the Northern Territory of Australia and Queensland, and also in northern and western Australia.
Biogeographic Regions:
australian 
(native ).
Habitat
This species occupies various fresh water areas such as lagoons, rivers, billabongs, and swamps.
Aquatic Biomes:
lakes and ponds; rivers and streams.
Physical Description
Crocodylus johnsoni can reach a maximum length of three meters. It has a light brown body with darker bands on its body and tail and lighter brown bands on its snout. It has a morphologically distinct narrow snout with approximately 68-72 teeth total consisting of 5 premaxillary teeth, 14-16 maxillary, and 15 mandibular teeth. The body is covered with scales that are generally large and provide wide armor on the back.
Some key physical features:
ectothermic ; bilateral symmetry .
Reproduction
The females nest in holes that are exposed on sandbars during the dry season from August through September. Mating occurs three to six weeks before laying. Clutches average in size between 13-20 eggs and hatch in about 65-95 days. Egg laying usually occurs at night. Eggs are faced with predation by monitor lizards and feral pigs. High and low temperatures (33-34C) produce female embryos while intermediate temperatures (32C) produces male embryos. The nests of eggs are left unguarded, but the mothers reappear in late October. At the end of the incubation period, the mothers carry the newly hatched young to the water in their mouths. The mothers then stay close to the young and protect them for a short period of time. In addition to being hole nesters, they are also sometimes called "pulse nesters" because all females in a given population nest within a brief three week period each season. Individuals reach reproductive maturity when they reach 1.5 meters in length.
Key reproductive features:
gonochoric/gonochoristic/dioecious (sexes separate).
Behavior
When hunting, these animals use a sit-and-wait method of grabbing prey with a swift sideways motion of the head.
Key behaviors:
motile .
Food Habits
This creature eats fish, insects, small invertebrates, amphibians, mammals, birds, and other small vertebrates. Large individuals may consume terrestrial prey.
Economic Importance for Humans: Negative
Occasional attacks on humans have been reported.
Economic Importance for Humans: Positive
Humans benefit from this species by using it for its meat, eggs, and its leather-producing hide.
Conservation Status
Long-term aboriginal hunting did not significantly affect the population despite advances made in tanning processes at the end of the 1950s that allowed the skins of this species, instead of those of the preferred saltwater crocodile, to be used as leather. Hunting did cause a decrease in populaton size but protective measures were taken in the early 1960s. In western Australia they were protected by law in 1962, and in 1964 in the Northern Territory. Queensland did not pass its protective laws until 1974. Illegal hunting continues but the main threat is the destruction of habitat. Small scale ranching and farming of these crocodiles exists.
Other Comments
Other common names include: Johnson's/Johnston's (river) crocodile, "Freshie", and fish crocodile. There are no recognized subspecies although darker-colored dwarf specimens have been identified. Also called Crocodylus johnstoni.
Contributors
Nikoma Boice (author), University of Michigan.
