Added 3 December 2000. Last updated 30 January 2006: added information for C. moreletii and updated C. acutus, and expanded Bibliography.

Crocodilians

Order CROCODILIA

Introduction

The following is a brief guide to the living crocodilian species. For further details consult the Bibliography and visit some of the Internet sites listed, especially the Crocodilian Group.

KEY: The sizes given are in feet and may be considered the "normal" length of a full-grown adult specimen. The sizes given in square brackets denote instances of some individuals, past or present, which have grown or can grow much larger.

Navigational note: to go to the Bibliography, click on B: to go back to the Quick Index, click on I.

QUICK INDEX

Family Crocodylidae

Crocodylus acutus, American Crocodile C. cataphractus, Slender-Snouted Crocodile C. intermedius, Orinoco Crocodile

C. johnstoni, Australian Freshwater Crocodile C. mindorensis, Philippines Crocodile C. moreletii, Morelet's Crocodile

C. niloticus, Nile Crocodile C. novaeguinae, New Guinea Crocodile C. palustris, Mugger Crocodile

C. porosus, Saltwater Crocodile C. rhombifer, Cuban Crocodile C. siamensis, Siamese Crocodile

Osteolaemus tetraspis, African Dwarf Crocodile

Subfamily Alligatorinae

Alligator mississippiensis, American Alligator A. sinensis, Chinese Alligator Caiman crocodilus, Spectacled Caiman

C. latirostris, Broad-Nosed Caiman Melanosuchus niger, Black Caiman Paleosuchus palpebrosus, Dwarf Caiman

P. trigonatus, Smooth-Fronted Caiman

Subfamily Gavialinae

Gavialis gangeticus, Indian Gavial Tomistoma schlegelii, False Gavial

Scientific Name Common Name Distribution Size Notes

Family Crocodylidae

Crocodylus acutus American Crocodile S USA (S Florida only), C America, northern S America (Columbia, Peru, Venezuela), Carribean 9-12' [21'] C. acutus is a somewhat timid species and fairly scarce throughout its range, including places where it was once abundant. It has not colonised areas populated by C. intermedius or M. niger. Apart from its usual range it may also occur as individuals on the Cayman and Tres Marias Islands and on Trinidad. It has a limited temperature tolerance, and in water of 65 deg F or less will sink into a torpor and drown. On the other hand it has a high tolerance of marine environments due to the 20-40 salt glands on its tongue. Anatomy: thin snout, especially in S. American individuals: this may help the latter in competition with caimans. Distinct median ridge extends along half the snout length. Maxillae have 13-14 pairs of teeth, lower jaw 15 pairs. Usually 4 large nuchal plates in a two by two arrangement: dorsal plates are arranged in 4-6 longitudinal rows comprising 15-16 transverse series. 2nd & 3rd front toes are slightly webbed: outer toes on hindfoot are united by a membrane. Subcaudal whorls of scales are interrupted by irregular groups of small scales. Coloration: adult animals are dorsally blackish-olive with yellowish underparts. Hatchlings are dorsally grey-green with blackish cross-bars (often broken into spots): 4-5 on body, 8-10 on tail. Cuban individuals lack these. Reproduction: breeding season is in northern spring. Eggs are laid mid-March to mid-May (February-May in Yucatán), peaking in April. Most hatchlings appear in late July-early August (rainy season). Nests are about 12-18" high and 10-12' wide, accommodating up to 35 eggs. They are usually located above beaches in hardwood thickets, shrubs or mangrove stands. Females will guard nests, except against humans. Incubation is about 85 days (70-80 in Yucatán). The female carries the hatchlings (9½" long) to water. Juvenile distress calls are usually answered by adults but older juveniles may sometimes be predatory. In the first month the hatchlings grow to 12", thereafter an extra inch per month. By four years old they are 4-5' in length, when they begin to employ the adult roar. B I

Crocodylus cataphractus Slender-Snouted Crocodile W & C Africa, Lake Tanganyika 7½-9' The Slender-Snouted Crocodile is a shy and secretive species found mainly in West and Central Africa, reaching as far east as Lake Tanganyika. It is easily distinguished from other crocodilians in its range by its long snout, which abruptly tapers to become quite slender (being 2½ times as long as wide at the level of the eyes). The end of the snout is bulbous, with two valved nostrils at the top. The tail is about 30-40% of the total length, with two raised keels. The rear toes are slightly webbed. It lives between sea level and 3,000ft (1,000m) in lakes and rivers in forest and forest-savannah mosaic, being sometimes found in savannah rivers. It will also use dams and swamps if the pools therein are large enough. Although a CITES Appendix I species, it is still threatened by hunting for bushmeat and parts for traditional medicine. When threatened it will hide in waterside vegetation rather than diving as Niles do, but it is nevertheless a fast and agile swimmer. It may use waterside holes as shelters. Specimens in Lake Tanganyika bask in secluded spots. Despite its size, C. cataphractus is primarily a fish eater, although it will take other fare such as reptiles, birds and amphibians. The young take tadpoles, frogs and insects. They are not known to be ambushers of creatures at the water's edge. A captive specimen lived 30 years in captivity. Scalation: pair of large occipital bumps form a transverse row on the neck, with a smaller bump on each side. Colour: uniform grey or brown. Specimens around Lake Tanganyika, especially in forested areas, may have black blotches or spots. Ventral surfaces are cream or yellow. Juveniles are brightly marked, being grey-green with irregular black blotches and crossbars: they also have proportionately short snouts. Reproduction: in Ivory Coast mating has been observed in February. In March-April the female constructs a nest of rotting vegetable matter on the elevated bank of a forest stream and guards it. She lays a clutch of 12-30 eggs and covers it with the rotting vegetation. At temperatures of 27-34 deg C incubation time takes 90-100 days. The juveniles enter the water quickly and spend the first part of their lives in backwaters and shallow flooded areas. B I

C. c. cataphractus 18-19 ventral shields

C. c. congicus 24-27 ventral shields

Crocodylus intermedius Orinoco Crocodile S America (Meta & Orinoco river systems) 12' [21'] The Orinoco Crocodile derives its common name from its range which is principally the Meta and Orinoco Rivers. Although a freshwater species, some individuals have been reported from Trinidad. Its closest relation is possibly C. acutus. The Orinoco Crocodile seems to prefer still waters: in the rainy season it may wander considerable distances to find still lakes and pools, while in the dry season it favours wide and deep rivers. In some areas it allegedly aestivates in caves under steep river banks. Prey is mainly fish and capybaras. The outlook for this crocodile species is difficult as it is still hunted for its hide which is considered more valuable than those of the caimans with which it is usually in competition. In addition, it is difficult to find viable populations in the wild on which observations can be made. Anatomy: long and relatively deep snout, lacks ridges but has median elevation, concave profile and unossified nasal septum. Maxillae have 13-14 pairs of teeth, lower jaw 15-16 pairs. Mandibular symphysis extends backwards to level of 6th, 7th or 8th tooth. Coloration: dorsally olive-brown, ventrally yellow. Reproduction: In January-February the female excavates a nest in sandbanks well above the water level. A clutch of 15-70 eggs is laid: these are subject to predation chiefly by tegus and black vultures. B I

Crocodylus johnstoni Australian Freshwater Crocodile N Australia (Kimberley, NE Queensland) 10' Unlike its larger congeneric, C. porosus, this species is strictly a freshwater dweller, being found in permanent areas of freshwater. It can be distinguished from the more dangerous "saltie" by its long and slender snout, which is smooth-scaled. It has enlarged nuchal shields in a single row separated from the smooth-skinned parietal area by <8 granular scales. Colour: dorsally grey or olive-brown with irregular dark mottling on the flanks and whitish ventral surfaces. Reproduction: females lay 20 eggs in sandbanks towards the end of the dry season in October-November. B I

Crocodylus mindorensis Philippines Crocodile Philippines (Luzon, Mindoro, Busuango, Masabate, Samar, Negros, Mindanao, Jolo and Culion) 4½-8' Sometimes regarded as a subspecies of the New Guinea Crocodile C. novaeguinae: Rogner points out however that the on the snout are more pronounced than in C. novaeguinae and that 80% of C. mindorensis specimens have 6 nuchal shields, as opposed to the 4 in C. novaeguinae (a characteristic admittedly shared by the other 20% of C. mindorensis individuals). Closely related to C. porosus, but differs from the latter by the presence of enlarged shields on the neck just behind the head: the ridges above the eyes are lower and more oblique. There are 16-18 very large ventral plates between the axilla and the hind limbs. Steel suggests that this is a creature of freshwater marshes, small lakes and tributaries of larger rivers, whereas Alcata does not mention marshes but cites "inland lakes and headwaters of rivers". He notes that the species, formerly abundant, was overhunted to the point of extinction. Coloration: very similar to that of C. porosus [Alcata]. Reproduction: constructs a nest in the dry season for the eggs. B I

Crocodylus moreletii Morelet's Crocodile Belize, Guatemala, Mexico 2-3½mSVL, 7½' Relatively broad-snouted species found in freshwater lakes, rivers, ponds and aguadas (bodies of water in forested areas).Invertebrates form most of the diet into subjuvenile size, while larger individuals take larger fish, birds, turtles and mammals. Anatomy: broad snout; dorsal surface of heady and body heavily armoured with bony scales; tail laterally compressed, with numerous groups of irregular small scales intercalated between caudal whorls. Coloration: adults dorsally dark brown or nearly black, lighter bleow; juveniles have lighter, yellowish dorsum with transverse black bands on body and tail. Reproduction: in the Yucatán area, females construct nests of decaying vegetation near the water in June-July. Clutch size is 20-40, incubation takes 75-80 days. B I

Crocodylus niloticus Nile Crocodile Africa 9-12' [18'] Along with the saltwater crocodile C. porosus, the Nile crocodile is one of those species potentially fatal to man, with hundreds of humans being killed or injured by them each year (although, in fairness, more humans are killed within this range by the hippopotamus). Within their range they can be easily distinguished from other species by their size and long jaws and prominent teeth. The eyes and valved nostrils are located on the top of the head and jaws. The plates on top of the head are fused to the skull. Hind feet are webbed. The tail makes up about 40% of the total length and has two raised dorsal keels. Young Niles eat small prey, often out of the water, but subadults prefer swamps and backwaters. Full adults take not only fish but also large mammals, a favourite tactic being to ambush animals coming to drink at the edge of waterholes. In some places they are able to take advantage of the seasonal migrations of large herds of such creatures as wildebeest. Colour: the young are greenish with irregular black markings on the dorsum and flanks and ventrally a straw-yellow. Adults are darker, olive to grey, with yellow or cream ventral surfaces. Reproduction: Niles reach sexual maturity in 12-15 years when they are about 2-3m in length. The breeding season commences in May when males start to establish a dominance hierarchy. Courtships take place in July-August. The female selects a sunny sandbank for her nest, which she will use for the rest of her life. In November she digs a hole 12-18" (30-45cm) deep and lays 16-80 white hard-shelled eggs. During this time the male remains in the vicinity but is not allowed near the nest. Time to hatching is 84-90 days. While still in the eggs the hatchlings emit high peeps which alert the mother, who opens the nest and carries the young in her mouth to the water. For the first 6-8 weeks the young remain in a sort of "creche", but later they dig burrows (sometimes communally) which they use as a shelter for 4-5 years. The reproductive biology and care of Nile crocodiles is reminiscent of avian species and has been studied for possible clues to the reproduction and care of young of extinct archosaurs, especially the dinosaurs. B I

Crocodylus novaeguinae New Guinea Crocodile New Guinea 18'

Crocodylus palustris Mugger/Marsh Crocodile W Pakistan, India, Bangladesh, Sri Lanka 7½' [12'] A largeish species found in large water bodies in the plains and up to 600m above sea level across its range. Although difficult to distinguish at sight from the more dangerous C. porosus, the two species do not occur together. Daniel claims that captive breeding for the skin trade has had some success. Other individuals may live in a semi-captive state in association with a religious establishment such as a temple. In the wild the animals usually make burrows for habitation: these may have a diameter of up to 80cm and lead for up to 4½m to a roomier chamber. The burrows may be situated in the sides of waterside hills, beneath rocks or at the foot of trees. Most hunting is done in the water and the diet is largely fish, but other vertebrates may be taken: scavenging has also been reported. However, the species is rarely dangerous to man, although Daniel notes that it will feed on corpses. A captive reportedly buried meat and fish given to it. Ecologically it has been reported that the muggers may perform a useful function in keeping numbers of coarse fish in check which otherwise thrive at the expense of commercially useful species: a similar claim has been made for Nile Crocodiles. Description: the snout is broad and lacks distinct ridges in front of the eyes; there is a row of 4 distinct and sharply raised post occipitals behind the head; the back is armoured with 16-17 transverse and 6 (sometimes 4) longitudinal rows of scutes embedded in the skin: ventrally the species lacks armour. The tail has two rows of flattened vertical scales that merge and continue as a single row to the tip. The toes are webbed. Coloration: dorsally olive, speckled with black: the black speckling is more distinct in young specimens. Ventrally white or yellowish white. Reproduction: in India, breeding takes place mid-January to March, depending partly on location. A hierarchy at least among males during breeding season is observed during this time. The female lays 3-40 eggs in a clutch (depending mainly on her age and size) and guards the nest she has built, as well as sometimes moistening it with water or urine from her cloaca. Hatching takes 2-3 months. Rogner notes that the Sri Lankan population is classified as the subspecies C. palustris kimbula, but that this distinction is somewhat questionable. B I

Crocodylus porosus Saltwater Crocodile Indo-Pacific, N Australia 20' [30'] The largest, most spectacular and probably most dangerous species of living crocodile, with a wide distribution and the ability to swim across sea if necessary. In recent history 30ft individuals were known, but human persecution (or in some cases defence) has reduced the normal size of a full-grown adult to 20'. That this is still a fearsome predator can be illustrated by the fact that at least a couple of years ago, one individual in the Malaysian peninsula had taken about 40 human victims and still not been caught. Alcata also mentiones that in the Philippines this animal is hated and feared. Normally, however, humans do not feature in their diet, but extreme caution must be taken in areas where C. porosus is known to live. It is found in coastal areas but also travels far inland. Anatomy: in appearance C. porosus can be distinguished by its large size and a short, blunt and granular-scaled snout. The enlarged nuchal shields are in 2 rows separated from the parietal area by >8 granular scales. Colour: grey, brown or almost black, with irregular dark mottling and whitish ventral surfaces. Reproduction: in Australia, females lay 60 eggs high up on river banks in the wet season. B I

Crocodylus rhombifer Cuban Crocodile C Cuba, Isle of Pines 7½' Very rare species of which there are several hundred individuals living in an area of contiguous marshland on the island. Despite this the future of the species seems brighter as the Cuban government is working hard to conserve it. The Cuban Crocodile seems to be more adept at moving about on dry land than some other crocodiles, raising itself higher above the ground. B I

Crocodylus siamensis Siamese Crocodile Thailand, Indochina, Java and Borneo 10-11½'

Osteolaemus tetraspis African Dwarf Crocodile W Africa 4½-6'

Subfamily Alligatorinae

Alligator mississippiensis American Alligator SE Mexico, Guatemala, Honduras, El Salvador 10-12' [18']

Alligator sinensis Chinese Alligator China 4-7' A very endangered species: some sources claim that only 130-150 individuals are still left in the wild. B I

Caiman crocodilus Spectacled Caiman S America ?' Name derives from the bony ridges around the eyesockets, giving the appearance of a pair of glasses. B I

Caiman latirostris Broad-nosed Caiman S America 6-7½' [9']

Melanosuchus niger Black Caiman S America (Amazonia and central S America) 9-13½ [18']'

Paleosuchus palpebrosus Dwarf Caiman NE S America as far east as Sao Paolo and as far south as Paraguay: range includes Columbia, British Guyana, Surinam and the mouth of the Amazon. 5'

Paleosuchus trigonatus Smooth-fronted Caiman Columbia, Venezuela, the Guyanas, Ecuador, Peru, Bolivia, the Amazon and Orinoco Rivers as far south as 10 deg lat. [Rogner] 4½-5' [7']

Subfamily Gavialinae

Gavialis gangeticus Indian Gavial Indian subcontinent, Burma 13½' [21'] An easily recognisable species thanks to its long snout full of teeth. Formerly these were common animals in the river systems of the subcontinent and Burma but are now seriously endangered and mostly confined to the Chambal, Girwa, Rapti and Narayani rivers of the Ganga river system. For most of the year they inhabitat deep pools at river junctions and bends and deep gorges in hilly country, but spread out with the monsoon flood waters, only to return to their normal habitat at the end of the season. They are not good movers on land and stay close to the river. Diet is mainly fish but opportunistically take other creatures, including corpses. Description: the jaws have 27-29 undifferentiated teeth on each side of the upper jaw and 25-26 on each side of the lower: the first 3 of the latter fit into notches in the upper jaw. Males can be distinguished by a large cartiliginous mass on the end of the snout. Coloration: adults are dark- or brownish olive, ventrally white or yellowish white. The young are greyish brown with 5 irregular transverse bands on the body and 9 on the tail. Reproduction: mating takes place December-January in the water. Nesting follows in March-April, the nests usually being sited on sand: the nesting season is said to not vary each year by more than 10 days, with all females in an area nesting within a week [Daniel]. A clutch may consist of anything between 10-96 eggs but is on average 40: incubation lasts 72-92 days. Sexual maturity is reached in females at lengths of 2½m and males at 3m.

Tomistoma schlegelii False Gavial S Thailand, Malaysia, Sumatra and Borneo 9-11½' .

Bibliography

The information above was culled from a number of sources as follows:

Crocodiles of the World, Rodney Steel. Invaluable overview of the crocodilians, giving a breakdown on the individual species as well as their evolutionary history and fossil remains of extinct crocodilians. We freely acknowledge our debt to this book!

General Care & Maintenance of Alligators, Caiman, and other Crocodilians, by Dan Malone and Theresa Moran, a slim (24-page) volume printed 1998 by ECO in the USA. Despite its slender size it is quite useful for the price, as long as you realise that it is an introduction rather than a complete guide. As an aside, I found it interesting that the authors chose to preface their book with the quotation from the Book of Job (Old Testament) where God points to the crocodile as one of the superlative mysteries of his creation. The Bible has often been cited as the source of much antipathy to reptiles, but in the passage the crocodile's awesome attributes are seen as only praiseworthy.

Echsen [Lizards] II, Manfred Rogner, Verlag Eugen Ulmer, 1992. It may seem surprising to find crocodilians listed in a book entitled Lizards, but in German crocodiles are (or were formerly) also known as Panzerechsen (literally "armoured lizards", and Rogner has some useful details on the anatomical differences to distinguish the various species and their care (though he stresses that crocodiles are really for zoological institutions rather than the private keeper).

Field Guide to the Reptiles of East Africa by Stephen Spawls, Kim Howell, Robert Drewes and James Ashe. Detailed and invaluable review of all reptile species in the region. Good details on the African species (all of which are just about included within the range).

Field Guide to Snakes and Other Reptiles of Southern Africa, Bill Branch, Struik, Cape Town 1998. Good details on C. niloticus.

Reptiles and Amphibians of Australia, Harold Cogger, 6th edition. Useful short accounts on C. porosus and C. johnstoni.

Guide to Philippine Flora and Fauna. Volume X, Amphibians and Reptiles, Prof. Angel C Alcala, Natural Resources Management Centre, Ministry of Natural Resources and University of the Philippines, 1986. Very useful field guide to the herps of this area, which is usually under-represented in literature. One slight drawback is that the photographs are black-and-white and the descriptions of colour for many species are drawn from preserved specimens: otherwise this book is to be recommended if you can obtain a copy. Contains short accounts of C. mindorensis and C. porosus.

The Book of Indian Reptiles and Amphibians, J C Daniel, Bombay Natural History Society, Oxford University Press, Oxford, 2002. Has good details on C. palustris, C. porosus and G. gangeticus.

Field Guide to Amphibians and Reptiles of the Maya World, Julian C Lee, Cornell University Press, 2000. Contains details for C. acutus and C. moreletii in the Yucatán area.

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Family Crocodylidae
Crocodylus acutus, American Crocodile	C. cataphractus, Slender-Snouted Crocodile	C. intermedius, Orinoco Crocodile
C. johnstoni, Australian Freshwater Crocodile	C. mindorensis, Philippines Crocodile	C. moreletii, Morelet's Crocodile
C. niloticus, Nile Crocodile	C. novaeguinae, New Guinea Crocodile	C. palustris, Mugger Crocodile
C. porosus, Saltwater Crocodile	C. rhombifer, Cuban Crocodile	C. siamensis, Siamese Crocodile
Osteolaemus tetraspis, African Dwarf Crocodile
Subfamily Alligatorinae
Alligator mississippiensis, American Alligator	A. sinensis, Chinese Alligator	Caiman crocodilus, Spectacled Caiman
C. latirostris, Broad-Nosed Caiman	Melanosuchus niger, Black Caiman	Paleosuchus palpebrosus, Dwarf Caiman
P. trigonatus, Smooth-Fronted Caiman
Subfamily Gavialinae
Gavialis gangeticus, Indian Gavial	Tomistoma schlegelii, False Gavial

Scientific Name	Common Name	Distribution	Size	Notes
Family Crocodylidae
Crocodylus acutus	American Crocodile	S USA (S Florida only), C America, northern S America (Columbia, Peru, Venezuela), Carribean	9-12' [21']	C. acutus is a somewhat timid species and fairly scarce throughout its range, including places where it was once abundant. It has not colonised areas populated by C. intermedius or M. niger. Apart from its usual range it may also occur as individuals on the Cayman and Tres Marias Islands and on Trinidad. It has a limited temperature tolerance, and in water of 65 deg F or less will sink into a torpor and drown. On the other hand it has a high tolerance of marine environments due to the 20-40 salt glands on its tongue. Anatomy: thin snout, especially in S. American individuals: this may help the latter in competition with caimans. Distinct median ridge extends along half the snout length. Maxillae have 13-14 pairs of teeth, lower jaw 15 pairs. Usually 4 large nuchal plates in a two by two arrangement: dorsal plates are arranged in 4-6 longitudinal rows comprising 15-16 transverse series. 2nd & 3rd front toes are slightly webbed: outer toes on hindfoot are united by a membrane. Subcaudal whorls of scales are interrupted by irregular groups of small scales. Coloration: adult animals are dorsally blackish-olive with yellowish underparts. Hatchlings are dorsally grey-green with blackish cross-bars (often broken into spots): 4-5 on body, 8-10 on tail. Cuban individuals lack these. Reproduction: breeding season is in northern spring. Eggs are laid mid-March to mid-May (February-May in Yucatán), peaking in April. Most hatchlings appear in late July-early August (rainy season). Nests are about 12-18" high and 10-12' wide, accommodating up to 35 eggs. They are usually located above beaches in hardwood thickets, shrubs or mangrove stands. Females will guard nests, except against humans. Incubation is about 85 days (70-80 in Yucatán). The female carries the hatchlings (9½" long) to water. Juvenile distress calls are usually answered by adults but older juveniles may sometimes be predatory. In the first month the hatchlings grow to 12", thereafter an extra inch per month. By four years old they are 4-5' in length, when they begin to employ the adult roar. B I
Crocodylus cataphractus	Slender-Snouted Crocodile	W & C Africa, Lake Tanganyika	7½-9'	The Slender-Snouted Crocodile is a shy and secretive species found mainly in West and Central Africa, reaching as far east as Lake Tanganyika. It is easily distinguished from other crocodilians in its range by its long snout, which abruptly tapers to become quite slender (being 2½ times as long as wide at the level of the eyes). The end of the snout is bulbous, with two valved nostrils at the top. The tail is about 30-40% of the total length, with two raised keels. The rear toes are slightly webbed. It lives between sea level and 3,000ft (1,000m) in lakes and rivers in forest and forest-savannah mosaic, being sometimes found in savannah rivers. It will also use dams and swamps if the pools therein are large enough. Although a CITES Appendix I species, it is still threatened by hunting for bushmeat and parts for traditional medicine. When threatened it will hide in waterside vegetation rather than diving as Niles do, but it is nevertheless a fast and agile swimmer. It may use waterside holes as shelters. Specimens in Lake Tanganyika bask in secluded spots. Despite its size, C. cataphractus is primarily a fish eater, although it will take other fare such as reptiles, birds and amphibians. The young take tadpoles, frogs and insects. They are not known to be ambushers of creatures at the water's edge. A captive specimen lived 30 years in captivity. Scalation: pair of large occipital bumps form a transverse row on the neck, with a smaller bump on each side. Colour: uniform grey or brown. Specimens around Lake Tanganyika, especially in forested areas, may have black blotches or spots. Ventral surfaces are cream or yellow. Juveniles are brightly marked, being grey-green with irregular black blotches and crossbars: they also have proportionately short snouts. Reproduction: in Ivory Coast mating has been observed in February. In March-April the female constructs a nest of rotting vegetable matter on the elevated bank of a forest stream and guards it. She lays a clutch of 12-30 eggs and covers it with the rotting vegetation. At temperatures of 27-34 deg C incubation time takes 90-100 days. The juveniles enter the water quickly and spend the first part of their lives in backwaters and shallow flooded areas. B I
C. c. cataphractus				18-19 ventral shields
C. c. congicus				24-27 ventral shields
Crocodylus intermedius	Orinoco Crocodile	S America (Meta & Orinoco river systems)	12' [21']	The Orinoco Crocodile derives its common name from its range which is principally the Meta and Orinoco Rivers. Although a freshwater species, some individuals have been reported from Trinidad. Its closest relation is possibly C. acutus. The Orinoco Crocodile seems to prefer still waters: in the rainy season it may wander considerable distances to find still lakes and pools, while in the dry season it favours wide and deep rivers. In some areas it allegedly aestivates in caves under steep river banks. Prey is mainly fish and capybaras. The outlook for this crocodile species is difficult as it is still hunted for its hide which is considered more valuable than those of the caimans with which it is usually in competition. In addition, it is difficult to find viable populations in the wild on which observations can be made. Anatomy: long and relatively deep snout, lacks ridges but has median elevation, concave profile and unossified nasal septum. Maxillae have 13-14 pairs of teeth, lower jaw 15-16 pairs. Mandibular symphysis extends backwards to level of 6th, 7th or 8th tooth. Coloration: dorsally olive-brown, ventrally yellow. Reproduction: In January-February the female excavates a nest in sandbanks well above the water level. A clutch of 15-70 eggs is laid: these are subject to predation chiefly by tegus and black vultures. B I
Crocodylus johnstoni	Australian Freshwater Crocodile	N Australia (Kimberley, NE Queensland)	10'	Unlike its larger congeneric, C. porosus, this species is strictly a freshwater dweller, being found in permanent areas of freshwater. It can be distinguished from the more dangerous "saltie" by its long and slender snout, which is smooth-scaled. It has enlarged nuchal shields in a single row separated from the smooth-skinned parietal area by <8 granular scales. Colour: dorsally grey or olive-brown with irregular dark mottling on the flanks and whitish ventral surfaces. Reproduction: females lay 20 eggs in sandbanks towards the end of the dry season in October-November. B I
Crocodylus mindorensis	Philippines Crocodile	Philippines (Luzon, Mindoro, Busuango, Masabate, Samar, Negros, Mindanao, Jolo and Culion)	4½-8'	Sometimes regarded as a subspecies of the New Guinea Crocodile C. novaeguinae: Rogner points out however that the on the snout are more pronounced than in C. novaeguinae and that 80% of C. mindorensis specimens have 6 nuchal shields, as opposed to the 4 in C. novaeguinae (a characteristic admittedly shared by the other 20% of C. mindorensis individuals). Closely related to C. porosus, but differs from the latter by the presence of enlarged shields on the neck just behind the head: the ridges above the eyes are lower and more oblique. There are 16-18 very large ventral plates between the axilla and the hind limbs. Steel suggests that this is a creature of freshwater marshes, small lakes and tributaries of larger rivers, whereas Alcata does not mention marshes but cites "inland lakes and headwaters of rivers". He notes that the species, formerly abundant, was overhunted to the point of extinction. Coloration: very similar to that of C. porosus [Alcata]. Reproduction: constructs a nest in the dry season for the eggs. B I
Crocodylus moreletii	Morelet's Crocodile	Belize, Guatemala, Mexico	2-3½mSVL, 7½'	Relatively broad-snouted species found in freshwater lakes, rivers, ponds and aguadas (bodies of water in forested areas).Invertebrates form most of the diet into subjuvenile size, while larger individuals take larger fish, birds, turtles and mammals. Anatomy: broad snout; dorsal surface of heady and body heavily armoured with bony scales; tail laterally compressed, with numerous groups of irregular small scales intercalated between caudal whorls. Coloration: adults dorsally dark brown or nearly black, lighter bleow; juveniles have lighter, yellowish dorsum with transverse black bands on body and tail. Reproduction: in the Yucatán area, females construct nests of decaying vegetation near the water in June-July. Clutch size is 20-40, incubation takes 75-80 days. B I
Crocodylus niloticus	Nile Crocodile	Africa	9-12' [18']	Along with the saltwater crocodile C. porosus, the Nile crocodile is one of those species potentially fatal to man, with hundreds of humans being killed or injured by them each year (although, in fairness, more humans are killed within this range by the hippopotamus). Within their range they can be easily distinguished from other species by their size and long jaws and prominent teeth. The eyes and valved nostrils are located on the top of the head and jaws. The plates on top of the head are fused to the skull. Hind feet are webbed. The tail makes up about 40% of the total length and has two raised dorsal keels. Young Niles eat small prey, often out of the water, but subadults prefer swamps and backwaters. Full adults take not only fish but also large mammals, a favourite tactic being to ambush animals coming to drink at the edge of waterholes. In some places they are able to take advantage of the seasonal migrations of large herds of such creatures as wildebeest. Colour: the young are greenish with irregular black markings on the dorsum and flanks and ventrally a straw-yellow. Adults are darker, olive to grey, with yellow or cream ventral surfaces. Reproduction: Niles reach sexual maturity in 12-15 years when they are about 2-3m in length. The breeding season commences in May when males start to establish a dominance hierarchy. Courtships take place in July-August. The female selects a sunny sandbank for her nest, which she will use for the rest of her life. In November she digs a hole 12-18" (30-45cm) deep and lays 16-80 white hard-shelled eggs. During this time the male remains in the vicinity but is not allowed near the nest. Time to hatching is 84-90 days. While still in the eggs the hatchlings emit high peeps which alert the mother, who opens the nest and carries the young in her mouth to the water. For the first 6-8 weeks the young remain in a sort of "creche", but later they dig burrows (sometimes communally) which they use as a shelter for 4-5 years. The reproductive biology and care of Nile crocodiles is reminiscent of avian species and has been studied for possible clues to the reproduction and care of young of extinct archosaurs, especially the dinosaurs. B I
Crocodylus novaeguinae	New Guinea Crocodile	New Guinea	18'
Crocodylus palustris	Mugger/Marsh Crocodile	W Pakistan, India, Bangladesh, Sri Lanka	7½' [12']	A largeish species found in large water bodies in the plains and up to 600m above sea level across its range. Although difficult to distinguish at sight from the more dangerous C. porosus, the two species do not occur together. Daniel claims that captive breeding for the skin trade has had some success. Other individuals may live in a semi-captive state in association with a religious establishment such as a temple. In the wild the animals usually make burrows for habitation: these may have a diameter of up to 80cm and lead for up to 4½m to a roomier chamber. The burrows may be situated in the sides of waterside hills, beneath rocks or at the foot of trees. Most hunting is done in the water and the diet is largely fish, but other vertebrates may be taken: scavenging has also been reported. However, the species is rarely dangerous to man, although Daniel notes that it will feed on corpses. A captive reportedly buried meat and fish given to it. Ecologically it has been reported that the muggers may perform a useful function in keeping numbers of coarse fish in check which otherwise thrive at the expense of commercially useful species: a similar claim has been made for Nile Crocodiles. Description: the snout is broad and lacks distinct ridges in front of the eyes; there is a row of 4 distinct and sharply raised post occipitals behind the head; the back is armoured with 16-17 transverse and 6 (sometimes 4) longitudinal rows of scutes embedded in the skin: ventrally the species lacks armour. The tail has two rows of flattened vertical scales that merge and continue as a single row to the tip. The toes are webbed. Coloration: dorsally olive, speckled with black: the black speckling is more distinct in young specimens. Ventrally white or yellowish white. Reproduction: in India, breeding takes place mid-January to March, depending partly on location. A hierarchy at least among males during breeding season is observed during this time. The female lays 3-40 eggs in a clutch (depending mainly on her age and size) and guards the nest she has built, as well as sometimes moistening it with water or urine from her cloaca. Hatching takes 2-3 months. Rogner notes that the Sri Lankan population is classified as the subspecies C. palustris kimbula, but that this distinction is somewhat questionable. B I
Crocodylus porosus	Saltwater Crocodile	Indo-Pacific, N Australia	20' [30']	The largest, most spectacular and probably most dangerous species of living crocodile, with a wide distribution and the ability to swim across sea if necessary. In recent history 30ft individuals were known, but human persecution (or in some cases defence) has reduced the normal size of a full-grown adult to 20'. That this is still a fearsome predator can be illustrated by the fact that at least a couple of years ago, one individual in the Malaysian peninsula had taken about 40 human victims and still not been caught. Alcata also mentiones that in the Philippines this animal is hated and feared. Normally, however, humans do not feature in their diet, but extreme caution must be taken in areas where C. porosus is known to live. It is found in coastal areas but also travels far inland. Anatomy: in appearance C. porosus can be distinguished by its large size and a short, blunt and granular-scaled snout. The enlarged nuchal shields are in 2 rows separated from the parietal area by >8 granular scales. Colour: grey, brown or almost black, with irregular dark mottling and whitish ventral surfaces. Reproduction: in Australia, females lay 60 eggs high up on river banks in the wet season. B I
Crocodylus rhombifer	Cuban Crocodile	C Cuba, Isle of Pines	7½'	Very rare species of which there are several hundred individuals living in an area of contiguous marshland on the island. Despite this the future of the species seems brighter as the Cuban government is working hard to conserve it. The Cuban Crocodile seems to be more adept at moving about on dry land than some other crocodiles, raising itself higher above the ground. B I
Crocodylus siamensis	Siamese Crocodile	Thailand, Indochina, Java and Borneo	10-11½'
Osteolaemus tetraspis	African Dwarf Crocodile	W Africa	4½-6'
Subfamily Alligatorinae
Alligator mississippiensis	American Alligator	SE Mexico, Guatemala, Honduras, El Salvador	10-12' [18']
Alligator sinensis	Chinese Alligator	China	4-7'	A very endangered species: some sources claim that only 130-150 individuals are still left in the wild. B I
Caiman crocodilus	Spectacled Caiman	S America	?'	Name derives from the bony ridges around the eyesockets, giving the appearance of a pair of glasses. B I
Caiman latirostris	Broad-nosed Caiman	S America	6-7½' [9']
Melanosuchus niger	Black Caiman	S America (Amazonia and central S America)	9-13½ [18']'
Paleosuchus palpebrosus	Dwarf Caiman	NE S America as far east as Sao Paolo and as far south as Paraguay: range includes Columbia, British Guyana, Surinam and the mouth of the Amazon.	5'
Paleosuchus trigonatus	Smooth-fronted Caiman	Columbia, Venezuela, the Guyanas, Ecuador, Peru, Bolivia, the Amazon and Orinoco Rivers as far south as 10 deg lat. [Rogner]	4½-5' [7']
Subfamily Gavialinae
Gavialis gangeticus	Indian Gavial	Indian subcontinent, Burma	13½' [21']	An easily recognisable species thanks to its long snout full of teeth. Formerly these were common animals in the river systems of the subcontinent and Burma but are now seriously endangered and mostly confined to the Chambal, Girwa, Rapti and Narayani rivers of the Ganga river system. For most of the year they inhabitat deep pools at river junctions and bends and deep gorges in hilly country, but spread out with the monsoon flood waters, only to return to their normal habitat at the end of the season. They are not good movers on land and stay close to the river. Diet is mainly fish but opportunistically take other creatures, including corpses. Description: the jaws have 27-29 undifferentiated teeth on each side of the upper jaw and 25-26 on each side of the lower: the first 3 of the latter fit into notches in the upper jaw. Males can be distinguished by a large cartiliginous mass on the end of the snout. Coloration: adults are dark- or brownish olive, ventrally white or yellowish white. The young are greyish brown with 5 irregular transverse bands on the body and 9 on the tail. Reproduction: mating takes place December-January in the water. Nesting follows in March-April, the nests usually being sited on sand: the nesting season is said to not vary each year by more than 10 days, with all females in an area nesting within a week [Daniel]. A clutch may consist of anything between 10-96 eggs but is on average 40: incubation lasts 72-92 days. Sexual maturity is reached in females at lengths of 2½m and males at 3m.
Tomistoma schlegelii	False Gavial	S Thailand, Malaysia, Sumatra and Borneo	9-11½'	.