Overview

Brief Summary

Biology

Very little is known about the ecology of this species. Females appear to construct mound-nests of dry leaves and peat onto which an average of 20 to 30 large eggs are laid (2). Unusually amongst crocodilians, there is no direct evidence that hatchlings receive any parental care and consequently mortality is thought to be high (2).  The slender snout is well adapted for catching fish but the false gharial exhibits a more generalised diet; also eating insects, crustaceans and small mammals (2).
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Description

The false gharial is an unusual freshwater crocodilian (a group that includes alligators, crocodiles, caimans and the gharial) about which very little is known. Like the gharial (Gavialis gangeticus) from which it gets its common name, this species has a slender snout (2). Juveniles are dark/chocolate brown with black banding on the tail and body, a creamy white belly and dark blotches on the jaws; much of this colouration is retained into adulthood (2). Controversy over the taxonomy of this species remains, as morphological features (other than the snout shape) suggest it belongs in the family Crocodylidae where it is currently placed, but recent biochemical and immunological evidence suggests a closer relationship with the gharial, indicating it should also be placed in the family Gavialidae (3).
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Distribution

Range Description

Data gathered between 1994 and 1998 indicates that T. schlegelii is widespread, although at a low density, throughout large areas of Sumatera, Kalimantan, and Sarawak, and still persists in peninsular Malaysia. Current information and sightings are now available from 39 localities in 10 different river drainages. Sebastian (1994) notes an additional three drainages in Borneo where the species is reported.
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Continent: Asia
Distribution: Indonesia (Sumatra, Borneo, Kalimantan, Java, Sulawesi),  Malaysia (Malay Peninsula), S Thailand, Vietnam  
Type locality: Karau river and Lake Lamoeda on river Doeson, Southern Borneo.
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Historic Range:
Malaysia, Indonesia

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Range

Historically found in South East Asia throughout the Malay Peninsula and also on Sumatra and Borneo (3). Today the false gharial appears to be extinct in Thailand and is seen only at low densities (although populations are widespread) in Malaysia and Indonesia (3). There are unconfirmed reports of sightings in Vietnam and Sulawesi (3).
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Swamps, rivers and lakes. Terrestial nest sites and basking areas.

Systems
  • Terrestrial
  • Freshwater
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Inhabits freshwater swamps, rivers and lakes, preferring slow-moving water and heavily vegetated habitats (2).
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Life History and Behavior

Life Expectancy

Lifespan, longevity, and ageing

Maximum longevity: 24.7 years (captivity)
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Tomistoma schlegelii

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 2 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

AATCGCTGACTTTTCTCCACCAACCACAAAGACATCGGCACCCTTTACTTTATCTTCGGAGCCTGAGCGGGAATAGTTGGAACAGCCCTA---AGCCTCCTTATTCGCACAGAACTAAGTCAACCCGGACCCCTCATAGGAGAC---GACCAAATCTATAATGTTATTGTTACCGCACATGCCTTTATTATGATTTTCTTCATAGTAATACCTATTATAATTGGGGGATTTGGAAACTGACTACTACCACTAATG---ATTGGCGCACCCGACATAGCATTCCCACGAATAAATAATATAAGCTTCTGATTACTCCCACCATCATTCACCTTACTGCTTTTCTCCGCTTTCATCGAAACTGGGGCTGGAACCGGATGAACAGTCTATCCGGCCCTAGCAGGAAACCTAGCCCACGCCGGACCCTCCGTAGACTTA---ACCATTTTCTCCCTTCACCTCGCAGGAGTATCTTCAATCTTAGGGGCAATTAACTTTATTACCACAGCCATTAACATAAAACCCCCAGCAATATCACAATACCAAACACCTCTTTTTGTATGATCTGTATTAATTACAGCTGTGCTTCTCCTACTTTCCCTACCAGTATTAGCTGCA---GGAATCACCATACTACTCACCGATCGAAACCTAAATACAACCTTCTTTGACCCCTCAGGCGGCGGAGACCCTATCCTATATCAACATCTCTTCTGATTCTTCGGCCACCCAGAAGTTTATATCCTTATCCTCCCAGGGTTTGGAATAATCTCCCATGTAGTCACCTTCTACTCAGGAAAAAAA---GAACCATTCGGGTATATGGGAATAGTGTGAGCCATAATATCAATTGGCTTCCTGGGTTTCATTGTTTGAGCTCATCACATATTTACAGTAGGAATAGACGTTGATACCCGAGCATATTTTACTTCCGCTACAATAGTAATCGCTATCCCCACCGGAGTAAAAGTATTCAGCTGGCTA---GCAACAATCTACGGAGGA---ATTATAAACTGACAAGCCCCCATACTCTGAGCATTAGGCTTTATTTTCTTATTTACAGTAGGAGGACTAACAGGAATCGTCCTAGCCAACTCATCACTAGACATTATTCTCCACGACACTTATTACGTAGTAGCACACTTCCACTACGTA---CTATCAATAGGGGCAGTATTCGCCATTATAAGTGGATTTACCCACTGGTTCCCCCTATTCACAGGATTTACCCTTCACCCAGCATGAACAAAAGCCCAATTCGCAATCATATTCACAGGAGTAAATCTAACCTTCTTCCCACAACACTTCTTAGGCCTTTCCGGGATGCCACGA---CGATATTCAGACTACCCAGACGCATATTCA---TTCTGAAATATATTATCATCAATTGGGTCGTTAATTTCTATAGTCTCTGTAATTCTCCTCATATTCATTGTATGAGAAGCATTCTCTTCAAAACGTAAAATT---GAGACACCAGAAATAACCATCACAAAT
-- end --

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Statistics of barcoding coverage: Tomistoma schlegelii

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
C1

Version
2.3

Year Assessed
2000
  • Needs updating

Assessor/s
Crocodile Specialist Group

Reviewer/s

Contributor/s

Justification
Unconfirmed reports from Vietnam and Sulawesi. Widespread though at low densities. From current information available from 39 different localities in ten different river drainages the population is estimated at below 2,500 mature individuals.

History
  • 1996
    Data Deficient
    (Baillie and Groombridge 1996)
  • 1996
    Data Deficient
  • 1994
    Endangered
    (Groombridge 1994)
  • 1990
    Endangered
    (IUCN 1990)
  • 1988
    Endangered
    (IUCN Conservation Monitoring Centre 1988)
  • 1986
    Endangered
    (IUCN Conservation Monitoring Centre 1986)
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Current Listing Status Summary

Status: Endangered
Date Listed: 06/14/1976
Lead Region: Foreign (Region 10) 
Where Listed: Entire


Population detail:

Population location: Entire
Listing status: E

For most current information and documents related to the conservation status and management of Tomistoma schlegelii , see its USFWS Species Profile

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Status

Classified as Endangered (EN - C1) on the IUCN Red List 2002 (1), and listed on Appendix I of CITES (4).
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Population

Population
A total population estimate is not possible but an estimate of below 2,500 mature adults was agreed by a consensus of active researchers as a cautious figure.
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Threats

Habitat destruction caused by the construction of dams, channelling and deforestation amongst others has been the main cause of the decline of this species and continues to be its main threat to this day (3). Intensive hunting in some areas, especially Sumatra, in the mid 20th Century also contributed greatly to the decline in population numbers (3). Further threats come from fishing practices, with false gharials either becoming caught in nets, poisoned by toxins used to kill fish, or else loosing their food source to local fishermen (2).
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Management

Conservation Actions

Conservation Actions
It is listed on CITES Appendix I.
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Conservation

International trade in the false gharial is prevented by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (1), and many of the known populations occur within protected areas (3). Recent population estimates of the false gharial are under 2,500 mature adults but data on distribution is still insufficient (2). Before a successful conservation management plan can be implemented more information needs to be collected on the current status of this species in Malaysia and Indonesia. Further research into behaviour and ecology must be carried out in order to identify priority habitats and population needs (3). A Tomistoma Task Force has recently been set up under the umbrella of the IUCN-SSC Crocodile Specialist Group (5).
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Wikipedia

False gharial

The false gharial (Tomistoma schlegelii), also known as the Malayan gharial, or false gavial is a freshwater crocodilian with a very thin and elongated snout. The false gharial is listed as a vulnerable species by IUCN as the population is estimated at below 2,500 mature individuals.[1]

Characteristics[edit]

Close-up of false gharial
Tomistoma skull at the Zoological Museum of the Zoological Institute of the Russian Academy of Sciences, St. Petersburg

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 body scalation. 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 enlarged nuchal scales are continuous with the dorsal 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-crested caudal 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.[3]

The snout is even slimmer than the snout of the slender-snouted crocodile and comparably as slender as that of the gharial .[citation needed] The false gharial is a large crocodilian, measuring only a bit smaller than the gharial. 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).[4] In some cases, males can reportedly grow to as much as 5 m (16 ft) in length.[5] Adult males weigh 150 to 250 kg (330 to 550 lb), while females are about 3.2 m (10 ft) long and weigh an average of 90 kg (200 lb).[citation needed]

Distribution and habitat[edit]

False gharials are native to Peninsular Malaysia, Sarawak, Sumatra, and Borneo, but were extirpated in Thailand. It is unclear if they remain in Java. Apart from rivers, they inhabit swamps and lakes.[1] In the 1990s, information and sightings were available from 39 localities in 10 different river drainages, along with the remote river systems of Borneo.[citation needed]

Prior to the 1950s, Tomistoma occurred in freshwater ecosystems along the entire length of Sumatra east of the Barisan Mountains. The current distribution in eastern Sumatra has been reduced by 30-40% due to hunting, logging, fires, and agriculture.[6]

Ecology and behaviour[edit]

Diet[edit]

Until recently, very little has been known about the diet or behavior of the false gharial in the wild; as a result of research by biologists details are slowly being revealed. In the past, the false gharial was thought to have a diet similar to its relative the gharial (only fish and very small vertebrates), but new evidence and occurrences have proven, despite the false gharial's narrow snout, it has a generalist diet. In addition to fish and smaller water animals, mature adults will prey on larger vertebrates, including proboscis monkeys, long-tailed macaques, deer, water birds, and reptiles.[7]

At the end of 2008, a 4-m female false gharial attacked and ate a fisherman in central Kalimantan; his remains were found in the gharial's stomach.[7] This was the first verified fatal human attack by a false gharial, although at least one other is suspected.[7]

Reproduction[edit]

False gharials are mound-nesters. Females lay small clutches of 13 to 35 eggs per nest, and appear to produce the largest eggs of extant crocodilians. Sexual maturity in females appears to be attained around 2.5 to 3 m (8.2 to 9.8 ft), which is large compared to other crocodilians.[6]

It is not known when they breed in the wild or when the nesting season is. Once the eggs are laid, and construction of the mound is completed, the female abandons her nest. Unlike most other crocodilians, the young receive no parental care and are at risk of being eaten by predators such as mongooses, tigers, leopards, civets, and wild dogs. The young hatch after 90 days and are left to fend for themselves.

Threats[edit]

The false gharial is threatened with extinction throughout most of its range due to the drainage of its freshwater swamplands and clearance of surrounding rainforests. The species is also hunted frequently for its skin and meat, and the eggs are often harvested for human consumption.[7]

Conservation[edit]

The false gharial is listed on CITES Appendix I.[1]

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.[7]

Yayasan Ulin (The Ironwood Foundation) is currently attempting to manage a wetland area in East Kalimantan which is known to contain the gharials.[8]

Taxonomy[edit]

Tomistoma petrolicum, an extinct relative of the false gharial from China

From a morphological standpoint, it was originally placed within the family Crocodylidae, but numerous molecular studies have consistently indicated that it is the nearest relative (the sister taxon) of the gharial.[2] Along with close fossil relatives such as Maroccosuchus, it is thus increasingly classed in the family Gavialidae.[9]

References[edit]

  1. ^ a b c d Crocodile Specialist Group (2014). "Tomistoma schlegelii". IUCN Red List of Threatened Species. Version 2014.1. International Union for Conservation of Nature. 
  2. ^ a b Willis, R. E.; McAliley, L. R.; Neeley, E. D.; Densmore Ld, L. D. (June 2007). "Evidence for placing the false gharial (Tomistoma schlegelii) into the family Gavialidae: Inferences from nuclear gene sequences". Molecular Phylogenetics and Evolution 43 (3): 787–794. doi:10.1016/j.ympev.2007.02.005. PMID 17433721.  edit
  3. ^ Brazaitis, P. (2001) A Guide to the Identification of the Living Species of Crocodilians. Science Resource Center, Wildlife Conservation Society
  4. ^ [1]
  5. ^ [2]
  6. ^ a b Bezuijen, M.R., Webb, G.J.W., Hartoyo, P., Samedi, Ramono, W.S., Manolis, S.C. (1998) The False Gharial (Tomistoma schlegelii) in Sumatra. In: Crocodiles. Proceedings of the 14th Working Meeting of the Crocodile Specialist Group, IUCN. The World Conservation Union, Gland, Switzerland and Cambridge, UK. Pp. 10–31.
  7. ^ a b c d e Rachmawan, D., Brend, S. (2009).Human-Tomistoma interactions in central Kalimantan, Indonesian Borneo Crocodile Specialist Group Newsletter January 2009 – March 2009. Volume 28 No. 1: 9–11.
  8. ^ http://www.speciesconservation.org/projects/Siamese-Crocodile/309
  9. ^ "Molecular Systematics of the Order Crocodilia". 
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