| False gharial | |
|---|---|
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| Captive false gharial inBerlin Zoo,Germany | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauromorpha |
| Clade: | Archosauriformes |
| Order: | Crocodilia |
| Family: | Gavialidae |
| Subfamily: | Tomistominae |
| Genus: | Tomistoma Müller, 1846 |
| Species: | T. schlegelii |
| Binomial name | |
| Tomistoma schlegelii (Müller, 1838) | |
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| Range of the false gharial | |
| Synonyms | |
Pseudogavialis schlegelii | |
Thefalse gharial (Tomistoma schlegelii), also known by the namesMalayan gharial,Sunda gharial andtomistoma is a freshwatercrocodilian of thefamilyGavialidae native toPeninsular Malaysia,Borneo,Sumatra andJava. It is listed asEndangered on theIUCN Red List, as the global population is estimated at around 2,500 to 10,000 mature individuals.[2]
Thespecies nameschlegelii honorsHermann Schlegel.[3][4]
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The false gharial is dark reddish-brown above with dark brown or black spots and cross-bands on the back and tail.Ventrals are grayish-white, with some lateral dark mottling. Juveniles are mottled with black on the sides of the jaws, body, and tail. The smooth and unornamented snout is extremely long and slender, parallel sided, with a length of 3.0 to 3.5 times the width at the base. All teeth are long and needle-like, interlocking on the insides of the jaws, and are individually socketed. The dorsal scales are broad at midbody and extend onto the sides of the body. The digits are webbed at the base.Integumentary sensory organs are present on the head and bodyscalation. Scales behind the head are frequently a slightly enlarged single pair. Some individuals bear a number of adjoining small keeled scales. Scalation is divided medially by soft granular skin. Three transverse rows of two enlargednuchal scales are continuous with thedorsal scales, which consist of 22 transverse rows of six to eight scales, are broad at midbody and extend onto the sides of the body. Nuchal and dorsal rows equals a total of 22 to 23 rows. It has 18 double-crestedcaudal whorls and 17 single-crested caudal whorls. The flanks have one or two longitudinal rows of six to eight very enlarged scales on each side.[5]
The false gharial has one of the slimmest snouts of any living crocodilian, comparable to that of theslender-snouted crocodile and thefreshwater crocodile in slenderness; only that of thegharial is noticeably slimmer.[6] Three mature males kept in captivity measured 3.6 to 3.9 m (12 to 13 ft) and weighed 190 to 210 kg (420 to 460 lb), while a female measured 3.27 m (10.7 ft) and weighed 93 kg (205 lb).[7] Females are up to 4 m (13 ft) long.[8] Males can grow up to 5 m (16 ft) in length and weigh up to 600 kg (1,300 lb).[9] The false gharial apparently has the largest skull of any extant crocodilian, in part because of the great length of the slender snout. Out of the eight longest crocodilian skulls from existing species that could be found in museums around the world, six of these belonged to false gharials. The longest crocodilian skull belonging to an extant species was of this species and measured 84 cm (33 in) in length, with a mandibular length of 104 cm (41 in). Most of the owners of these enormous skulls had no confirmed (or even anecdotal) total measurements for the animals, but based on the known skull-to-total length ratio for the species they would measure approximately 5.5 to 6.1 m (18 to 20 ft) in length.[10]
Three individuals ranging from 2.9 to 4.05 m (9 ft 6 in to 13 ft 3 in) in length and weighing from 79 to 255 kg (174 to 562 lb) had abite force of 1,704–6,450 N (383–1,450 lbf).[11]
Thescientific nameCrocodilus (Gavialis) schlegelii was proposed bySalomon Müller in 1838 who described a specimen collected in Borneo.[12] In 1846, he proposed to use the nameTomistoma schlegelii, if it needs to be placed in a distinctgenus.[13]
The genusTomistoma potentially also contains severalextinct species likeT. cairense,T. lusitanicum,T. taiwanicus, andT. coppensi. However, these species may need to be reclassified to different genera as evidence suggests they may beparaphyletic.[14][15]
The false gharial's snout broadens considerably towards the base and so is more similar to those of truecrocodiles than to thegharial (Gavialis gangeticus), whoseosteology indicated a distinct lineage from all other living crocodilians.[6] However, although moremorphologically similar toCrocodylidae based on skeletal features, recent molecular studies usingDNA sequencing consistently indicate that the false gharial and by inference other related extinct forms traditionally viewed as belonging to the crocodylian subfamilyTomistominae actually belong toGavialoidea and Gavialidae.[16][17][18][19][20][21][14][22]
Fossils of extinctTomistoma species have been found in deposits ofPaleogene,Neogene, andQuaternary ages inTaiwan,Uganda,Italy,Portugal,Egypt andIndia, but nearly all of them are likely to be distinct genera due to older age compared to the false gharial.[23]
The belowcladogram of the major living crocodile groups is based on molecular studies and shows the false gharial's close relationships:[17][20][21][14][22]
The following cladogram shows the false gharial's placement within the Gavialidae; it is based on atip dating study, for whichmorphological,DNA sequencing andstratigraphic data were analysed:[14]
The false gharial is native toPeninsular Malaysia and the islands ofBorneo andSumatra; it is locally extinct inSingapore,Vietnam andThailand.[2] It inhabits peat swamps and lowlandswamp forests.[24]
Prior to the 1950s,Tomistoma occurred in freshwater ecosystems along the entire length of Sumatra east of theBarisan Mountains. The current distribution in eastern Sumatra has been reduced by 30-40% due to hunting, logging, fires, and agriculture.[25]The population has been estimated to comprise less than 2,500 mature individuals as of 2010.[24]
Until recently, very little was known about the diet or behaviour of the false gharial in the wild. Details are slowly being revealed. In the past, the false gharial was thought to have a diet of only fish and very smallvertebrates, but more recent evidence indicates that it has ageneralist diet despite its narrow snout. In addition to fish and smaller aquatic animals, mature adults prey on larger vertebrates, includingproboscis monkeys,long-tailed macaques,deer,water birds, andreptiles.[26] There is an eyewitness account of a false gharial attacking acow inEast Kalimantan.[24]
The false gharial may be considered an ecological equivalent toNeotropical crocodiles such as theOrinoco andAmerican crocodiles, which both have slender snouts but a broad diet.[6]
The false gharial is a mound-nester. Females lay smallclutches of 13–35 eggs per nest and appear to produce the largest eggs of living crocodilians. They attain sexual maturity at a length of around 2.5 to 3 m (8 ft 2 in to 9 ft 10 in), which is large compared to other crocodilians.[25]Courtship coincides with periods of rainfall in November to February and from April to June.[7]
In 2008, a 4-m female false gharial attacked and ate a fisherman in centralKalimantan; his remains were found in the gharial's stomach. This was the first verified fatal human attack by a false gharial.[26] However, by 2012, at least two more verified fatal attacks on humans by false gharials had occurred indicating perhaps an increase of human-false gharial conflict possibly correlated to the decline of habitat, habitat quality, and natural prey numbers.[27]
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The false gharial is threatened by habitat loss in most of its range due to thedrainage of freshwater swamps and conversion for commercial plantation of oil palms.[2]It is also hunted for its skin and meat, and its eggs are often harvested for human consumption.[26]Population surveys carried out in the mid 2000s indicated that the distribution of individuals is spotty and disconnected, with a risk ofgenetic isolation.[28]Some population units in unprotected areas do not bear viable breeding adults.[29]
The false gharial is listed onCITES Appendix I.[2]
Steps have been taken by the Malaysian and Indonesian governments to prevent its extinction in the wild. There are reports of some populations rebounding in Indonesia, yet with this slight recovery, mostly irrational fears of attacks have surfaced amongst the local human population.[26]
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