Chinese alligator
The Chinese alligator, also known as the Yangtze alligator, China alligator, or historically the muddy dragon, is a crocodilian endemic to China. It and the American alligator are the only living species in the genus Alligator of the family Alligatoridae. Dark gray or black in color with a fully armored body, the Chinese alligator grows to in length and weighs as an adult. It brumates in burrows in winter and is nocturnal in summer. Mating occurs in early summer, with females most commonly producing 20–30 eggs, which are smaller than those of any other crocodilian. The species is an opportunistic feeder, primarily eating fish and invertebrates. A vocal species, adults bellow during the mating season and young vocalize to communicate with their parents and other juveniles. Captive specimens have reached age 70, and wild specimens can live past 50.
Living in bodies of fresh water, the Chinese alligator's range is restricted to six regions in the province of Anhui, as well as possibly the provinces of Jiangsu and Zhejiang. Originally living as far away from its current range as Japan, the species previously had a wide range and population, but beginning in 6000 BC, multiple threats, such as habitat destruction, caused the species' population and range to decline. The population in the wild was about 1,000 in the 1970s, decreased to below 130 in 2001, and grew after 2003, with its population being about 300 as of 2017. Listed as critically endangered by the International Union for Conservation of Nature, multiple conservation actions have been taking place for this species.
The Chinese alligator has been a part of Chinese literature since the third century. In the late 13th century, Marco Polo became the first person outside of China to write about it. In some writings, the Chinese alligator has been associated with the Chinese dragon. Many pieces of evidence suggest that the Chinese alligator was an inspiration for the Chinese dragon.
History and taxonomy
The oldest definitive record of the Chinese alligator is from the late Pliocene of Japan, around 3 million years old. Pleistocene fossils show that its range was once much more extensive, extending northwards to Shandong and southwards to the Taiwan Strait.Chinese alligators were mentioned in Chinese literature very early; for example, in the Classic of Poetry, whose poems were composed between the 11th and 7th centuries BCE. Marco Polo was the first person outside of China to write about the alligator, when he came to China and saw it in the late 1200s. He said that the alligator lived in "caverns" in the day and hunted at night, and that humans targeted its meat and skin, with its gall bladder having multiple medical purposes. He stated that it was found in lakes, rivers, and springs in the province "Karazan". In 1656, Martino Martini, a priest, wrote that the Chinese alligator lived in the river Yangtze and was "much feared by the local residents". Unlike Polo, Martini wrote his description using information from Chinese literature. Chinese alligators were later thought to give Buddhist priests merit if the priests were to buy alligators held in captivity and release them. In 1869, Robert Swinhoe saw a Chinese alligator in an exhibit in Shanghai and wrote the following year:
Classification
The Chinese alligator was scientifically described by French naturalist Albert-Auguste Fauvel in 1879 as Alligator sinensis; though Fauvel only noticed mentions of them in Chinese literature since about 222–227 CE. The genus Alligator had previously contained only the American alligator since its creation in 1807. Fauvel wrote a detailed description of the species in a book titled Alligators in China: Their History, Description & Identification, including information about its historical account. In 1947, it was suggested to group the Chinese alligator in a separate genus from its American relative, due to the Chinese alligator's bony plate on its upper eyelid. This bony plate is present in caimans, but is rarely present in the American alligator. At the time, the plate was thought to not appear in the American alligator at all. This produced the belief that the Chinese alligator's relationship with other crocodilians was between caimans and American alligators. Paulus Edward Pieris Deraniyagala described the genus Caigator the same year, which only contained the Chinese alligator, making its scientific name Caigator sinensis. However, paleontology has shown that the Chinese alligator has evolved from other now-extinct members of the genus Alligator. This and the fact that the American alligator does infrequently have a bony plate on its eyelid have caused Caigator sinensis to now be classified as a synonym of Alligator sinensis. There is still not a consensus among biologists that the American and Chinese alligators belong to the same genus, despite multiple studies comparing the biochemistry, histology, and various other aspects of the two crocodilians.The evolutionary relationships of alligators can be shown in the cladogram below:
Etymology
The genus, Alligator, is based on the Spanish word el lagarto. The specific name, sinensis, is from the Latin plural possessive sinaensis, meaning "belonging to China".Description
One of the smallest species of crocodilians, the Chinese alligator attains a length of and weight of as an adult. Females are roughly three-quarters the length of males. It is less than half the size of the American alligator, which typically grows to a length of for males and for females. Reports are known of alligators in China reaching in past centuries, but these are no longer thought to be accurate. The largest reported female measured and weighed, while the largest reported male measured and weighed.The Chinese alligator is almost completely black or dark gray in color as an adult. It has a short and broad snout, which points slightly upwards and narrows at the end. Its head is robust, more so than that of the American alligator, with a bony septum dividing its nostrils. It has 72–76 teeth, of which 13–14 are maxillary, five premaxillary, and 18–19 mandibular. Four specimens measuring in length and weighing had a bite force of. Unlike the American alligator, the Chinese alligator is fully armored, including its belly. It contains up to 17 rows of scales across its body, which are soft on its belly and side and rougher on its back. Its upper eyelids have bony plates on them, a feature usually not present in the American alligator. Its tail is wider than that of the American alligator. It does not have webbed feet, in contrast to the American alligator, which has extensive webbing on its toes.
Ecology
The Chinese alligator brumates in burrows during winter. After this period of dormancy, it frequently spends time in the sun before summer begins. It is nocturnal throughout summer, feeding at night and sheltering in the daytime, to avoid both humans and the summer heat. This behavior gives it the ability to live in areas where humans are common. A docile species, it generally does not intentionally hurt humans.Burrowing
This alligator brumates from late October to mid-April, emerging in early May. It constructs its burrows next to ponds and other small bodies of water, using its head and front legs to dig into the ground. They can be large and complex, containing multiple rooms, water pools, and entrances. Most of them are long, with each room having enough space for alligators to turn around after entering. Outside of winter, the burrows serve as retreat sites for the alligators and in summer are where they take shelter in the daytime. The temperature inside them is never colder than. The burrows can be problematic for farmers, as they cause destruction of farm dykes.Life cycle
The breeding season of the Chinese alligator is early summer, with the rate of mating being highest in mid-June. The alligator breeds earlier in the year if temperatures are higher. During the time of mating, males commonly search around ponds to find a mate and both male and female specimens are often aggressive to each other. The species exhibits polygamy, with single males mating with multiple females and/or a single female mating with several males. A study of 50 clutches showed multiple paternity in 60% of them, with up to three males contributing. Nests are typically built about 2–3 weeks after mating, from July to late August. Constructed by the females, they are composed of rotting plants, such as leaves, and are high. Females prefer to assemble them in areas that have a thick canopy and are far from human disturbance. Because islands frequently satisfy both of these conditions, they are often used as nesting sites. Nests are always near water sources. Individuals often return to the same nesting site yearly, although intraspecific competition and environmental changes can force them to change nesting sites.Generally laid at night, mating typically produces 20–30 eggs, although according to the International Union for Conservation of Nature, clutch size ranges between 10 and 40 eggs. After the eggs are laid, the females sometimes leave the nest, but other times stay to protect the eggs. The eggs are about in length, in diameter, and in weight, making them smaller than the eggs of any other crocodilian. They are typically incubated for about 70 days. On average, the temperature of incubation is, including the day and night. This temperature controls whether a young alligator will be male or female, a feature present in many other reptiles. A higher incubation temperature also increases the hatching rate. Young hatch in September, assisted by their mothers.
Newborn alligators, like their eggs, are the smallest of any crocodilian, with a length of and weight of. Unlike adults, they have light speckles on their bodies and heads. Mothers help them leave the nest and bring them to the water after hatching. They grow very little in their first year, due to being able to feed for only about 2 months after hatching before the winter. A 2002 study showed that the Chinese alligator is two-thirds the length of the American alligator and one-half its weight at birth, but is one-half its length and one-tenth its weight after one year. Young depend on their mothers to protect them during their first winter, as their small size makes them an easy prey target.
The alligator grows quickly in its first few years, with its growth rate slowing at age five. According to the National Zoological Park, females reach maturity roughly four to five years after birth, although other sources estimate that they mature at age six to seven. It can live to over 50 years, and has been known to reach age 70 in captivity. It cannot breed past its 50s.