The Asian giant softshell turtle (''Pelochelys cantorii)'', also known commonly as Cantor's giant softshell turtle and the frog-faced softshell turtle, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

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

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Trionychidae Trionychidae is a family of turtles, commonly known as softshell turtles or simply softshells. The family was described by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to li ...

. The species is native to

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

. The species is critically endangered and in the 20th century has disappeared from much of its former range.

Taxonomy

''P. cantorii'' is not found in

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

, while the two other members of the genus '' Pelochelys'', '' P. bibroni'' and '' P. signifera'' are both restricted to New Guinea. ''P. cantorii'' is relatively unstudied, and the current species may actually be composed of several

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

. One study from 1995 showed that what was once thought to be ''P. cantorii'' in New Guinea was actually ''P. bibroni'', and the earlier studies of ''P. cantorii'' only described populations farther to the west. The classification of P. cantorii is Family: Trionychidae, Order: Testudines. A genome study revealed that several genes related to tumor resistance, growth, and aging were more active in P. cantorii. The genes found were VWA5A, ABCG2, A2M, and IGSF1.They are related to tumor resistance, growth, and aging. P. cantorii fits into turtle evolution because P. cantorii became separate from its closest turtle relatives about 59 million years ago. Turtles split from the common ancestor of birds and crocodiles around 256 million years ago. The populations of Asian giant softshell turtles in the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

"may be distinct" based on genetic analysis, implying the possibility of unique genetic traits in this population. More research is needed to confirm if the critically-endangered Philippine population is a distinct species.

Description

The Asian giant softshell turtle has a broad head, and small eyes close to the tip of its snout. The

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

is smooth and olive-colored. Juveniles may have dark-spotted carapaces and heads, with yellow around the carapace. Despite reports that it can grow up to in length and is the world's largest extant freshwater turtle, this maximum size and title is murky at best. Apparently the largest specimen carapace length, , known is considered suspect and the heaviest specimen known (weighing approximately was actually a misidentified Yangtze giant softshell turtle. A more realistic range of carapace length for this species is reportedly and it is one of about a half-dozen giant softshell turtles from three genera that reach exceptionally large sizes, i.e. in excess of in mass.

Behavior and reproduction

''P. cantorii'' is an

ambush predator Ambush predators or sit-and-wait predators are carnivorous animals that capture their prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey u ...

and primarily

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

, feeding on

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

mollusks Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The num ...

and fish (although some aquatic plants may also be eaten). The turtle spends 95% of its life buried and motionless, with only its eyes and mouth protruding from the sand. It surfaces only twice a day to take a breath, and lays 20–28 eggs sized around in diameter in February or March on riverbanks.

Morphological variation

Asian Giant Softshell Turtle at Philippine National Museum

Morphological differences in neural bone count have been noted between specimens of ''P. cantori'' found in the Philippines and specimens found in mainland Asia.

Etymology

The specific name, ''cantorii'', is in honor of Danish zoologist

Theodore Edward Cantor Theodore Edward Cantor () (1809–1860) was a Danish physician, zoologist and botanist. He described several new species of reptiles and amphibians, and six species have been named in his honor. Cantor was born to a Danish Jewish family; his m ...

. Additionally, they are named for their softshells because they have soft, leathery shells that are completely devoid of scales.

Geographic range and habitat

The species ''P. cantorii'' is primarily found in inland, slow-moving, freshwater rivers and streams. Some evidence indicates that its range extends to coastal areas, as well. It occurs in eastern and southern

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...

Burma Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and ha ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

Laos Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...

Cambodia Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline ...

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

, eastern and southern

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, the

(

Luzon Luzon ( , ) is the largest and most populous List of islands in the Philippines, island in the Philippines. Located in the northern portion of the List of islands of the Philippines, Philippine archipelago, it is the economic and political ce ...

and

Mindanao Mindanao ( ) is the List of islands of the Philippines, second-largest island in the Philippines, after Luzon, and List of islands by population, seventh-most populous island in the world. Located in the southern region of the archipelago, the ...

), and

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

(

Kalimantan Kalimantan (; ) is the Indonesian portion of the island of Borneo. It constitutes 73% of the island's area, and consists of the provinces of Central Kalimantan, East Kalimantan, North Kalimantan, South Kalimantan, and West Kalimantan. The non-Ind ...

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

, and

Sumatra Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...

Conservation

The Asian giant softshell turtle is classified as a

Critically Endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

and has been forced out through habitat destruction, disappearing from much of its range. Prior to 2007, it was last seen in Cambodia in 2003. A 2007 survey of one area of the

Mekong River The Mekong or Mekong River ( , ) is a transboundary river in East Asia and Southeast Asia. It is the world's List of rivers by length, twelfth-longest river and List of longest rivers of Asia, the third-longest in Asia with an estimated l ...

in Cambodia found the turtle in abundance along a stretch of the river. In the Philippines, a juvenile Cantor's turtle known as "cagot" appeared and was captured by a fisherman along the Addalam River, Cabarroguis, Quirino, Isabela. In 2001, this turtle was sent to

Chicago Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...

and its identity confirmed. The geographic range of the turtle was initially murky in the Philippines, but recent studies have confirmed their range in at least two islands, Luzon and Mindanao. Unfortunately, the invasive

Chinese softshell turtle The Chinese softshell turtle (''Pelodiscus sinensis'') is a species of softshell turtle that is native to mainland China (Inner Mongolia to Guangxi, including Hong Kong) and Taiwan, with records of escapees—some of which have established intr ...

has become present in these two islands due to illegal introductions from mainland

. The

Department of Environment and Natural Resources The Department of Environment and Natural Resources (DENR; ) is the Executive Departments of the Philippines, executive department of the Philippine government responsible for the conservation, management, development, and proper use of the cou ...

lists the Asian giant softshell turtle as a protected species and its trade is illegal under Philippine law, while it allows, through specific legal processes, the culling and catching of the invasive Chinese softshell turtle for import purposes, as to reduce the number of the invasive species, especially in areas where the indigenous Asian giant softshell turtle is present. Unfortunately, not all locals are aware of the difference between the two species which look similar, and this has led to the illegal catching of Asian giant softshell turtles in some instances. The department has yet to resolve this key issue in the conservation of Asian giant softshell turtles in the Philippines, where genetic studies have confirmed that the Philippine populations have distinct features from other populations in Asia. The reptile has been evaluated as an

EDGE species Edge or EDGE may refer to: Technology Computing * Edge computing, a network load-balancing system * Edge device, an entry point to a computer network * Adobe Edge, a graphical development application * Microsoft Edge, a web browser developed by ...