Embryos of E. orbicularis exhibit temperature-dependent sex determination, based on egg incubation temperature and hormonal factors that cause gonadal differentiation. During the thermosensitive period of incubation, eggs at temperatures below 25 degrees C will become male embryos, while eggs at temperatures above 30 degrees C will become female embryos. Posthatchling growth includes body elongation and development of a streamlined body structure. The tails of young are nearly as long as the shell, but become shorter with age. Specimens about 5 inches in length are considered fully developed adults. Males of this species mature earlier and generally remain smaller than females, but they have similar growth rates. Growth is responsive to and limited by ecological factors, including hatchling size, food availability, genetic factors, and quality of their habitats. Alterations of diet and prolonged activity affect growth rate. Growth rate decreases as size increases and slows considerably following sexual maturity.
Development - Life Cycle: temperature sex determination
Hinges in the plastron allow these turtles to withdraw into the shell and close off shell openings as protection from predators. Hatchlings and eggs are preyed upon by various animals including: herons, raccoons, bears, king snakes, ghost crabs, hermit crabs, dogs, gulls, alligators, crocodiles, foxes, rats, cats, and cormorants. Young turtles are at risk of becoming prey to predacious fish species as well. Adult E. orbicularis are subject to attack by wild dogs, coyotes, carnivorous birds, and humans.
Known Predators:
Extensively variable coloration is seen within this generally small species, however there is usually some light speckling on a dark (often black) background color. The shape and coloration of the shell changes with age. Young E. orbicularis have a rounded shell, and the shields are rough and slightly keeled, uniformly dark brown above and black below, with a yellow spot on each marginal and plastral shield along the rim of the carapace. As they age, the dorsal shields become smooth and are generally spotted or striated with yellow markings on a dark background. The head, limbs, and tail are dark with yellow or light brown spots and small dots. Shell size ranges from 12 to 38 cm (5 to 15 in.) and they have 12 pairs of marginal shields. The head is covered with smooth skin and the limbs are extensively webbed. Emys orbicularis has a flexible hinged plastron that is loosely united to the carapace by ligaments. Males of this species mature earlier and generally remain smaller than females, but they have similar growth rates.
Range length: 12 to 38 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Compared to many other reptiles and amphibians, this species has a relatively long lifespan. Individuals living in northern populations tend to exhibit longer lifespans than those in more southern locations. Records have shown average Emys orbicularis turtles living fifteen years or longer and adults may potentially live for decades. Mortality is very high for hatchlings due to abundant predators and lack of protection from the elements. Captive individuals may live several years longer than those living in natural populations. The age of turtles can be determined by counting the annuli growth rings on the scutes of the shell. It is assumed that only one growth ring forms annually.
Average lifespan
Status: captivity: 27.9 years.
Average lifespan
Sex: male
Status: captivity: 11.7 years.
This species lives in freshwater areas, including ponds, lakes, slow-moving streams and other lentic regions. They select terrestrial locations with open, high, and sandy soil habitats for nesting. These turtles search for habitats in shallow, fertile areas with adequate food supplies and minimal predators.
Habitat Regions: temperate ; terrestrial ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: swamp
Other Habitat Features: riparian
Emys orbicularis, commonly known as European pond turtles, is found in southern and central Europe, northwestern Africa (roughly Morocco through to Tunisia), and in humid areas of the Middle East and Central Asia as far east as the Aral Sea. Historically the species was more common and had a wider distribution than it does today.
Biogeographic Regions: palearctic (Native )
Emys orbicularis is a generalsit carnivore diet. Most small aquatic animals are prey, and their diet may shift as they grow and can eat larger animals. Worms, insects, frogs, and fishes comprise their main sources of sustenance and they generally feed in water. These turtles attack and capture their prey, biting with a sideward turn of the head, then tearing the prey to pieces with sharp claws on the forelimbs. Generally, in the wild, their prey must be moving to be seized. In captivity, these turtles may resort to eating fruits and vegetables.
Animal Foods: amphibians; fish; insects; mollusks; aquatic or marine worms
Primary Diet: carnivore (Piscivore , Insectivore , Eats non-insect arthropods)
Emys orbicularis serves a significant role in the food web of freshwater habitats. They prey upon worms, insects, frogs, and fishes, and are in turn preyed upon by other reptiles, fish, predatory birds, and large mammals.
Freshwater turtles, including Emys orbicularis, are hunted as sources of food, used for medicinal applications, and kept as pets.
Positive Impacts: pet trade ; food ; source of medicine or drug ; research and education; controls pest population
Emys orbicularis is generally harmless and does not normally have extensive contact with humans
(Gadow 1958).
Populations of Emys orbicularis have been declining over the past century. Their geographic range has diminished and it will most likely continue to decrease duet to habitat destruction. Several solutions may be successful in replenishing these populations. Governmental and ecological organizations will need to regulate turtle hunters and egg collectors, protect habitats, and reduce destructive factors, including pollution and siltation.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: lower risk - near threatened
During the mating season members of this species emit short piping sounds. Other possible vocalizations include whistles, chirps, and groans, which are often used in stressful situations. Head movements are also used to communicate. Auditory stimuli may be involved in mating rituals.
Communication Channels: visual ; tactile ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Emys orbicularis is the only species in this genus. E. orbicularis was previously named Testudo orbicularis and Testudo europaea. This is the only species in the Emydidae to reach geographic ranges above 45 degrees latitude.
Once a pair-bond is formed, courtship and copulation follow. Mating may occur in sandy areas if not hidden within foliage. Most males and females cohabitate peacefully, but some adults are more aggressive toward each other.
After reaching sexual maturity at age 5 to 6 years, adult Emys orbicularis mate and the female produces approximately eight to ten white, hard-shelled, elongate eggs per clutch, averaging 15 to 25 mm in length, which are laid on land. The pregnant female selects a suitable spot of hard soil free from grass and other dense vegetation and prepares and moistens the ground. Then the female uses her stiff tail to bore a hole into the ground approximately five inches deep. The hind-limbs dig out the hole, and the eggs are laid at the bottom in one layer, and are divided and distributed by the feet. The female covers the hole with the removed soil, stamps the soil firm and flat, and abandons the nest. After approximately 90 to 100 days of incubation, the young hatch according to locality and seasonal conditions. Some embryos hibernate within the egg overwinter and do not hatch until the following spring when conditions are more favorable. These turtles mate repeatedly and may produce multiple clutches per year.
Breeding season: spring to early summer
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Males in this species make no parental investement, and female investment in her offspring ends when she lays her eggs and covers her nest.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)
The European pond turtle (Emys orbicularis), also called commonly the European pond terrapin and the European pond tortoise, is a species of long-living freshwater turtle in the family Emydidae.[3] The species is endemic to the Western Palearctic.
The following 14 subspecies are recognized as being valid.[2]
A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Emys.
The subspecific name eiselti is in honor of Viennese herpetologist Josef Eiselt (1912–2001).[4]
The subspecific name fritzjuergenobsti is in honor of German herpetologist Fritz Jürgen Obst (1939–2018).[4]
The subspecific name lanzai is in honor of Italian herpetologist Benedetto Lanza.
E. orbicularis is found in southern, central, and eastern Europe, West Asia and parts of Mediterranean North Africa. In France, there are six remaining populations of significant size; however, they appear to be in decline. This turtle species is the most endangered reptile of the country.[5] In Switzerland, the European pond turtle was extinct at the beginning of the twentieth century but reintroduced in 2010.[5]In the early post-glacial period, the European pond turtle had a much wider distribution, being found as far north as southern Sweden and Great Britain,[6] where a reintroduction has been proposed by the Staffordshire-based Celtic Reptile & Amphibian, a group specialising in the care, research, and rehabilitation of native European and British herpetiles.[7] In 2004, the European pond turtle was found in the former Soviet territories of Estonia, which are currently under Russian jurisdiction.[8]
Fossil evidence shows that E. orbicularis and Testudo hermanni were both present in Sardinia during the Pleistocene, but molecular evidence suggests the extant populations of both species on the island were introduced in modern times.[9]
E. orbicularis prefers to live in wetlands that are surrounded by an abundance of lush, wooded landscape. They also feed in upland environments.[10] They are usually considered to be only semi-aquatic (similar to American box turtles), as their terrestrial movements can span 1 km (0.62 mi). They are, occasionally, found travelling up to 4 km (2.5 mi) away from a source of water.[10]
The European pond turtle is a medium-sized turtle, and its straight carapace length varies quite a bit across its geographic range, from 12 to 38 cm (4.7 to 15.0 in). The carapace is dark brown to blackish, with a hint of green. The head and legs are spotted with yellow. The plastron is yellowish.
An important factor that affects the development of E. orbicularis is temperature and thermal conditions. It has been reported that differential growth rates of the same species occur, including variation of body size and clutch size, because of varying temperatures in certain areas.[11] Due to evident patterns of sexual dimorphism, E. orbicularis adult males are always found to be smaller than females. In males, smaller plastra offer them a wider mobility compared to females. In females, due to their differential diet and foraging habits, there may be a correlation to an adaptive effect on their skull and head morphology.[11]
E. orbicularis eats a mixed diet of plants and animal matter that can increase the efficiency of its digestive process.[10] It has been reported that an adult's diet starts from a carnivorous diet and progresses to a more herbivorous diet as it ages and grows in size. This is similar to other omnivore emydid turtles.[10] As E. orbicularis grows in age and becomes an adult, the amount of plant material consumption increases during the post breeding period. E. orbicularis may prefer less energetic food after the breeding season, a period of time where most of its energy is spent to recover from reproduction.[10]
Most freshwater turtles lay their eggs on land, typically near a water source, but some species of Emys have been found to lay their eggs no less than 150 m (490 ft) from water.[3] The search for nesting areas, by adult females, can last several hours to several days. Once an appropriate site is found, females take their time with the construction of the nest, painstakingly excavating a small pit out of the soft substrate purely by usage of her small forelimbs. Once satisfied with the depth of the nest, she will turn around (facing away from the nest) and proceed with egg-laying, gently dropping the eggs down and into a small pile. This process varies in duration; laying can take merely half an hour or upwards of several hours, depending on weather, interference by other animals, humans, etc. When laying is complete (and still facing away from the nest), the female turtle will use her back limbs this time, to cover and close the nest. This is another variable routine which can take up to another four hours.[12]
Nest fidelity is a characteristic that is unique to female European pond turtles—selecting a nesting site based on its ecological characteristics—and then returning there for future laying, so long as the site has not changed.[3] E. orbicularis females tend to look to a new nesting site if there are visible changes to the original nest’s surroundings, or because of dietary and metabolic changes. If an E. orbicularis female must change from nest to nest, she will typically select a site in relatively close proximity.[3] In addition, females may also lay eggs in an abandoned nesting site if the conditions are an improvement, and deemed to be better suited for egg survival. If the environmental conditions of a nesting site change, this may influence the development of the eggs, the survival of the hatchlings and/or their sex ratio. Due to unforeseen ecological changes, such as thick vegetation growing over a season (and blocking sun to the nest), a nest site may become inadequate for incubating eggs. Females that do not exhibit nesting fidelity, and continue to lay in the same area for long periods of time—even with the ecological changes—may end up producing more male offspring, as the cooler and darker conditions promote more males developing.[3] Since the sex of these turtles is temperature-dependent, a change in temperature may produce a larger number of males or females which may upset the sex ratio.[3]
Climate has an effect on the survival of E. orbicularis hatchlings. Hatchlings are only able to survive under favorable weather conditions, but due to regular annual clutch sizes and long lifespan, E. orbicularis adults, along with many freshwater turtles, balance out loss of hatchlings due to climate.[12]
The species E. orbicularis has become rare in most countries even though it is widely distributed in Europe. The building of roads and driving of cars through natural habitats is a possible factor that threatens the populations of the European pond turtle. Road networks and traffic often carry complex ecological effects to animal populations such as fragmenting natural habitats and creating barriers for animal movement. Mortality on the road is most likely due to females selecting nests near roads which places a potential danger for the hatchlings as well. Hatchlings that wander too closely to roads are more likely to be killed and put the future population in danger. Although the possibility of roads being a major causation for the mortality of E. orbicularis is a rare phenomenon, long-term monitoring is necessary.[12]
Introduced exotic species such as Trachemys scripta scripta and T. s. elegans, known commonly as Florida turtles, also put in danger the native Emys species in many parts of Spain (and possibly in other parts of southern Europe), since these exotic turtles are bigger and heavier than the native pond turtles.[13][14] The usual life span of E. orbicularis is 40–60 years. It can live over 100 years, but such longevity is rare.
E. orbicularis hosts several species of parasites, including Haemogregarina stepanovi, monogeneans of the genus Polystomoides, vascular trematodes of the genus Spirhapalum, and many nematode species.
Historically, E. orbicularis had been maintained as pets; however, this practice has been restricted due to protection laws. Ownership of wild caught specimens is prohibited. Only registered captive bred specimens may be owned by private individuals. Due to human impact, the European pond turtle has been found to be relocated in areas distant from its origin. However, it is possible to localize and indicate a region of origin with genetic testing.[15]
The population of E. orbicularis in Ukraine is listed under Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).[16]
The European pond turtle (Emys orbicularis), also called commonly the European pond terrapin and the European pond tortoise, is a species of long-living freshwater turtle in the family Emydidae. The species is endemic to the Western Palearctic.
