False gharial

From Wikipedia, the free encyclopedia
Jump to: navigation, search
False gharial
Tomistoma schlegelii false gharial LA zoo 03.jpg
False gharial, Tomistoma schlegelii
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Gavialidae[2]
Subfamily: Tomistominae
Genus: Tomistoma
Müller, 1846
Species: T. schlegelii
Binomial name
Tomistoma schlegelii
Müller, 1838
Tomistoma schlegelii Distribution.png
Range of Tomistoma

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". 

External links[edit]