The brahminy river turtle or crowned river turtle (''Hardella thurjii'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Geoemydidae The Geoemydidae (formerly known as Bataguridae) are one of the largest and most diverse families in the order Testudines (turtles), with about 70 species. The family includes the Eurasian pond and river turtles and Neotropical wood turtles. Mem ...

. The species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

South Asia South Asia is the southern subregion of Asia, which is defined in both geographical Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth descr ...

Taxonomy

The genus ''Hardella'', to which the species ''Hardella thurjii'' belongs, is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus.

Geographic range

''Hardella thurjii'' is found in northern

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...

, and

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...

in the watersheds of the

Ganges The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...

Brahmaputra The Brahmaputra is a trans-boundary river which flows through Tibet, northeast India, and Bangladesh. It is also known as the Yarlung Tsangpo in Tibetan, the Siang/Dihang River in Arunachali, Luit in Assamese, and Jamuna River in Bangla. I ...

, and Indus rivers.

Description

''Hardella thurjii'' has a shell with a large, moderately flat, dark brown or black carapace (

dorsal surface Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

) and a yellow or black plastron (ventral surface). The shell is up to in length in females, and is shorter in males. The lower jaw is heavily dented.

Sexual dimorphism

''Hardella thurjii'' exhibits

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

. Mature females are three times the size of mature males. According to Das, maximum straight carapace length in females is , but in males maximum straight carapace length is only .

Reproduction

The reproductive habits of ''H. thurjii'' are unique among reptiles in that the females lay their eggs under water rather than on dry land. Their reproductive cycle follows seasonal changes in the water levels of the rivers in which they live. In autumn, females lay their eggs under water, where higher water levels submerge the eggs for 40 to 45 days. In the winter, lower water levels expose the eggs for five months. The rising water levels of spring submerge the almost mature eggs once again, and the turtles hatch in the river. Indian zoologist Dhruvajyoti Basu first documented the unique reproductive habits of the brahminy river turtle in 2011. The Prague Zoo incubated the first brahminy river turtle which was born in captivity in 2012.

Taxonomy

Geographic range

Description

Sexual dimorphism

Reproduction

References

External links

Further reading