CSL
Crocodylus porosus (SCHNEIDER, 1801)


NAMES | DISTRIBUTION | HABITAT | STATUS | APPEARANCE | IMAGES | DIET | BREEDING | CONSERVATION

FAMILY:
ALLIGATORIDAE

A. mississippiensis
A. sinensis
C. crocodilus
C. c. apaporiensis
C. c. fuscus
C. latirostris
C. yacare
M. niger
P. palpebrosus
P. trigonatus

FAMILY:
CROCODYLIDAE

C. acutus
C. intermedius
C. johnstoni
C. mindorensis
C. moreletii
C. niloticus
C. novaeguineae
C. palustris
C. porosus
C. rhombifer
C. siamensis
M. cataphractus
O. tetraspis
T. schlegelii

FAMILY:
GAVIALIDAE

G. gangeticus

DICHOTOMOUS KEY
[German]

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STATUS OF INFORMATION:
This information was most-recently updated January 2009 and is considered up-to-date. Please contact me directly regarding updates or corrections.

COMMON NAMES:
Australian Saltwater Crocodile, Estuarine Crocodile, 'Saltie', Indo-Pacific Crocodile (not generally accepted), Singapore small grain (probably due to resemblance to C. siamensis), Baya, Buaja, Buaya muara, Gator (regional Australian name, not to be confused with A. mississippiensis), Gatta Kimbula, Gorekeya, Kone huala, Jara Kaenumken, Pita Gatteya, Pukpuk (Aboriginal name), Rawing crocodile, Semmukhan Muthlelei, Sea-going crocodile, Subwater crocodile, Man-eating crocodile

NAME ETYMOLOGY:
> Crocodylus is derived from the Greek krokodeilos which means literally "pebble worm" (kroko = pebble; deilos = worm, or man) referring to the appearance of a crocodile.
> porosus means "full of callosities", derived from porosis (Greek for "callosity") + osus (Latin for "full of"), referring to the rugose and bumpy upper surface of the snout in large adults

SUBSPECIES:
C. p. minikanna has been suggested, but is not officially recognised.
Hybrids with C. siamensis exist in crocodile farms.

DISTRIBUTION:
[CLICK ON MAP FOR DETAILED RANGE]
Distribution map Australia, Bangladesh, Brunei, Myanmar (Burma), Cambodia, China, India (including Andaman Islands), Indonesia, Malaysia, Palau (Caroline Islands) , Papua New Guinea, Philippines, Singapore, Sri Lanka, Solomon Islands, Thailand, Vanuatu (Banks Islands), Vietnam. Single individuals can be found some distance from their usual range (e.g. Japan, islands in the Indian Ocean), as they can travel long distances (over a thousand km) by sea - barnacles have been found on the scales of a few stray individuals. This sea-faring ability probably helps to explain their wide distribution. Historically present on the Seychelles islands (now extinct).

HABITAT:
As its name implies, this species has a high tolerance for salinity, being found in brackish water around coastal areas and in rivers. However, it is also present in freshwater rivers, billabongs and swamps. Movement between different habitats occurs between the dry and wet season, and as a result of social status - juveniles are raised in freshwater areas, but eventually sub-adult crocodiles are usually forced out of these areas (used for breeding by dominant, territorial adults), into more marginal and saline areas. Subordinate animals unable to establish a territory in a tidal river system are either killed or forced out into the sea where they move around the coast in search of another river system. In recent years in northern Australia, saltwater crocodile populations in some areas have recovered to such an extent that increasing numbers are being forced further upstream into marginal habitat.

STATUS:
     CITES: Appendix I, except Australian, Papua New Guinea (Appendix II), Indonesia (Appendix II, annual quota for ranching)
     IUCN Red List: LRlc (LOW RISK, LEAST CONCERN)
     Estimated wild population: 200,000 to 300,000
Summary: Widely distributed and numerous in Australia and PNG, but depleted elsewhere

APPEARANCE:
[click on image for enlargement]
Head drawing The saltwater crocodile is the largest living crocodilian species based on confirmed measurements. It is also the world's largest living reptile in terms of mass. Adult males can reach sizes of up to 6 meters (20 feet) with possible reports of exceptionally rare individuals of nearly 7 metres (23 feet). However, the largest confirmed individual was measured as 20.7 feet (6.3 metres) taking into account partial tail loss. There is always a lot of interest over the largest ever recorded saltie. In general, males over 5 m (17 feet) in length are extremely rare. Females are smaller, the normal maximum adult size being 2.5 m to 3 m (8 to 10 feet). Maximum weight varies, but large salties have been known to exceed 1,000 kg as 18 to 19 foot adults. 5 metre adults are closer to 400 to 500 kg. This is a large-headed species with a heavy set of jaws. A pair of ridges run from the eye orbits along the centre of the snout, becoming more distinct with age. The upper surface of the top jaw becomes very rugose in large adult males. Scales on the flanks are more oval in shape than other species, although belly scales are rectangular, even and relatively small. Osteoderms are restricted to the back and a small nuchal cluster on the neck. Juveniles are normally pale tan in colour with black stripes and spots on the body and tail. A small percentage of animals in some regions tend to be much lighter in colour (hypomelanistic), although very dark (hypermelanistic) animals are occasionally also seen. The juvenile colouration persists for several years, growing progressively paler and less colourful with more indistinct bands which never completely disappear even in large adults (most of which are covered in mud, grime and algae and hence their base colour becomes very indistinct). Mature adults are generally dark, with lighter tan or grey areas. The ventral surface (belly) is creamy yellow to white in colour, except the tail which tends to be more grey on the underside nearer the tip. Dark bands and stripes are present on the lower flanks, but do not extend onto the belly region. Very occasionally, one or two black spots can be seen on the belly scales, but these are considered anomalous.

Dentition codeDENTITION:
4 (rarely 5) pre-maxillary; 13-14 maxillary; 15 mandibular
Total no. of teeth = 64-68

IMAGES:
[click on image for enlargement]

Click Crocodiles leaping to capture food Click Adult crocodile basking in sun Click Very large adult crocodile
Click Gomek, a very large captive adult Click Gomek being fed Click Saltie on sandbank

DIET:
Saltwater crocodiles take a wide variety of prey, although juveniles are restricted to smaller items such as insects, amphibians, crustaceans, small reptiles and fish. The larger the animal grows, the greater the variety of items that it includes in the diet, although relatively small prey still make up the majority of the diet even in large adults. Prey items include crustaceans (e.g. mudcrabs) and vertebrates (e.g. turtles, goannas/lizards, snakes, shore and wading birds). Large adults occasionally take much larger prey include buffalo and domestic livestock, wallabies, wild boar, monkeys etc.

BREEDING:
Breeding territories are usually established along tidal rivers, creeks and freshwater areas. Females reach sexual maturity at lengths of 2.2 to 2.5 m (10 to 12 years old). Males mature later (3.2 m, at around 16 years old). Females on average lay 40 to 60 eggs (this can range from 25 to 90) in mound nests made from vegetation (usually grasses and vines) and mud. These are normally constructed between the months of November and March during the wet season, but this varies slightly geographically. The mound helps to insulate the eggs from temperature extremes, hides them from predators, stops them from dehydrating, and also serves to raise the eggs above the ground to minimise the risk of flooding. Many nests are still flooded every year, however, killing all the unhatched embryos - in saltwater crocodiles flooding is the main cause of embryo mortality, not destruction by predators. If the nest is in danger of getting too dry, the female has apparently been observed to splash water onto it from a purpose-dug, adjacent pool, although the veracity of this observation is unknown. Although the female stays near the nest, eggs do occasionally fall foul of predators (e.g. monitor lizards, feral wild pigs in Australia) and human egg collectors. Juveniles normally hatch after 80 to 90 days but this varies with temperature (80 days at a sustained 32 celsius, longer if cooler). The female digs the hatchlings out of the nest when they start their characteristic
chirping sounds, assisting some of them to the water by picking them up carefully and carrying them within the mouth. A lot of research has been carried out into TSD (Temperature-dependant Sex Determination) in this species, which is of value for captive breeding programs to influence the sex ratio, and to produce faster growing males for farming purposes. The highest percentage of males are produced around 31.6°C, with more females a few degrees above and below this. It is estimated that less than 1% of hatchlings will survive to reach maturity, due to flooding, predation (e.g. turtles, goannas, C. johnstoni), competition for resources, and social pressures (territorial males will kill and eat juveniles - they are one of the limiting factors in population growth along with competition).

CONSERVATION:
Many species of crocodilians are falsely viewed as man-eaters, but fear of this species is not unfounded, with a number of people injured or killed each year, although in most cases these tragedies can be avoided with increased awareness. However, loss of life has led to a degree of antipathy towards the species, making conservation measures more difficult to implement.

Given its relatively wide distribution, control of trade has historically been difficult until recent years. The commercial value of the hide is very high (the most valuable of any crocodile species), due to the lack of ventral osteoderms which otherwise make tanning difficult, and the size and shape of the belly scales. Unregulated hunting mainly between 1945 and 1970 caused a dramatic decline throughout the range of the species. This has been controlled in some areas, notably Australia, but threats from habitat destruction still exist. Protection in some countries is often ineffective, and while illegal trade is relatively insignificant now for this species, killing due to fear is becoming an increasing problem.

Australia has been the centre for most of the extensive research carried out on this species, and several model breeding and conservation programs exist there. It is estimated that there are at least 100,000 to 150,000 crocodiles in the northern three states of Australia (Western Australia, Queensland and Northern Territory where the largest population base exists), so the problem has now shifted to one of persuading landowners and public alike of the value of the species which is otherwise only seen as destructive. Sustainable use programs have been implemented in the Northern Territory, and have proven to be highly successful in giving people an incentive to preserve not only the crocodiles but more importantly the habitat which supports them. These primarily involve collection of eggs from wild nests, with payment for the eggs being given to the landowners. The hatchlings are then sold to crocodile farms for raising and skin production. Extensive surveys are conducted with the harvesting, which has demonstrated no detectable impact of the harvesting program on population growth. A trial harvest of wild, adult crocodiles involving aboriginal communities was started in 1997 - the first time crocodiles had been legally hunted in the Northern Territory for 26 years. Some discussion of safari-style hunting is now taking place, directed by traditional Aboriginal landowners, but such programs are yet to be implemented.

Although populations are recovering in some areas, others are less positive. Habitat destruction and illegal hunting can be major problems (e.g. Irian Jaya). The population in Sri Lanka is in grave danger of extirpation due to local fears and attitudes, linked with habitat removal. Feral buffalo populations in Australia were responsible for destroying a lot of nesting habitat in the Northern Territory in the 1970s and 1980s, although feral eradication programs have reduced this problem considerably. Restocking programs in India (Bhitarkanika National Park in Orissa) have met with success, showing potential for other areas, although these need to be found. A sustainable use program established in Papua New Guinea has set the standard for similar projects in this and other species of crocodilian. These are based upon both wild cropping and ranching schemes. Farming in other areas (particularly Australia) is now performed on a large scale. Despite this, basic survey information is still lacking in other parts of this species' range (e.g. Indonesia).

The future of the species seems to be very secure at the moment, given the large population bases in Australia and Papau New Guinea. However, it is likely that the range of the species will be severely reduced through extirpation of many small populations in various countries unless management programs can be implemented, or more effective control and protection set up. The idea of sustainable use remains controversial, yet it is has been clearly demonstrated to be effective in the conservation of this species. The only areas where the species is likely to disappear are those where proper management and conservation programs do not sufficiently protect the wild populations.

MORE INFORMATION:
For more information on distribution and conservation issues for this species,see the CSG
Action Plan resource.

SIGNIFICANT REFERENCES:

  • Messel, H, & Vorlicek, GC (1989). Ecology of Crocodylus porosus in northern Australia. In: Crocodiles. Their Ecology, Management and Conservation. A Special Publication of the IUCN/SSC Crocodile Specialist Group. IUCN, Gland, Switzerland. pp. 163-184
  • Ortega, G, & Regoniel, P (1993). Conservation, management and farming of crocodiles in the Philippines. CFI News 6(1): 4-11
  • Solmu, GC (1994). Status of Crocodylus porosus and Crocodylus novaeguineae population in Papau New Guinea, 1981-1994. In: Crocodiles. Proceedings of the 12th Working Meeting of the Crocodile Specialist Group. IUCN, Gland, Switzerland. pp. 77-102
  • Webb, GJW, Manolis, SC & Ottley, B (1994). Crocodile management and research in the Northern Territory: 1992-94. In: Crocodiles. Proceedings of the 12th Working Meeting of the Crocodile Specialist Group. IUCN, Gland, Switzerland. pp. 167-180
  • Webb, GJW, Hollis, GJ & Manolis, SC (1991). Feeding, growth, and food conversion rates of wild juvenile saltwater crocodiles (Crocodylus porosus). J. Herpetology 25(4): 462-473
  • Webb, GJW & Manolis, SC (1989). Crocodiles of Australia. Reed Books Pty. Ltd., NSW, Australia. pp. 160
  • Webb, GJW & Messel, H (1978). Morphometric analysis of Crocodylus porosus from the North Coast of Arnhem Land, Northern Australia. Aust. J. Zool. 26: 1-27
  • Webb, GJW, Sack, GS, Buckworth, R & Manolis, SC (1983). An examination of Crocodylus porosus nests in two northern Australian freshwater swamps, with an analysis of embryo egg mortality. Aust. Wildl. Res. 10: 571-605
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