Emys orbicularis

Description

Although this species exhibits variations in coloration throughout its range, there is usually some light (yellow or light brown) speckling on a dark (usually black) background color. The head, limbs, and tail are dark with yellow or light brown spots and small dots. The head is covered with smooth skin and the limbs are extensively webbed. Some populations can be nearly entirely black with very few yellow markings at all.

The shape and coloration of the shell changes with age. Young 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 color of the male's iris varies from region to region, from red, brownish-yellow and yellow to pure white, while the eyes of females are generally yellow but occasionally also white.

Shell size ranges from 5 to 15 inches, and there are 12 pairs of marginal shields. It has a flexible hinged plastron that is loosely united to the carapace by ligaments, which allows it to withdraw its head and limbs into the shell. Males of this species mature earlier and generally remain smaller than females.

There are currently 14 described regional subspecies, which differ in size, colour and markings. In general, individuals from the north of the range tend to be markedly larger and darker than their southern counterparts.

Distribution and Habitat

As its name suggests, the European pond turtle is found in southern and central Europe, but its range also extends into northwestern Africa and humid areas of the Middle East and Central Asia, as far east as the Aral Sea.

It inhabits a variety of freshwater areas, including ponds, lakes, slow-moving streams and other still water regions with adequate food supplies and minimal predators.

Diet

This turtle feeds primarily on worms, insects, frogs, and fishes. It generally feeds in the water, attacking and capturing the 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.

Reproduction

Mating season begins immediately following hibernation at the end of March and ends around May, depending on the latitude. Male turtles "wake up" earlier and actively seek out female partners, using water-soluble pheromones secreted by receptive females as a positional cue. Both males and females prefer larger partners, as these promise a reproductive advantage.

3 to 16 (9-10 average) white, hard-shelled, elongate eggs, averaging 0.5 to 1 inch are laid on land in 1-3 separate ovipositions in May and June (but up to July). The pregnant female selects a suitable spot of hard soil free from grass and other dense vegetation and prepares and moistens the ground. She then 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.

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.

The European pond turtle is sexually mature at 5-6 years, and can live more than 100 years in the wild.

Other Habits and Behaviors

During the day, these turtles bask with their bodies stretched out for long periods of time upon stones or banks lying motionless. From underwater, they survey the area and prey with just the nose and eyes emerged above the surface, or conceal themselves behind or within floating vegetation.

This species exhibits male dominance hierarchies, particularly during breeding seasons. They may also exhibit territoriality and agonistic behaviors during food competition. Their behavioral movements include head extension, bobbing, biting, and similar activities. They have been known to assume dominant and subordinate postures. In captivity they become very tame, but in their native habitats they are extremely shy and cautious.

Most males and females cohabitate peacefully, but some adults are more aggressive toward each other.

Adults exhibit pair-bonding and live in small groups. Their activities and behaviors are altered by changes in season and environmental conditions. For example, feeding decreases with decreased temperatures. Generally, this species performs regional migration, emigration, and active foraging.

European pond turtles can remain below water for many hours before returning to the surface.

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.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Reptilia
order Chelonia
family Emydidae
genus & species Emys orbicularis

SOURCE
Animal Diversity Web animaldiversity.org/accounts/Emys_orbicularis/

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This page was last updated on June 16, 2017.