Mute turtles
| Mute turtles | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Black- buttoned mute turtles, Graptemys nigrinoda hatchlings |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Graptemys | ||||||||||||
| Agassiz , 1857 |
The turtle genus of the mute turtles ( Graptemys ) found in the rivers of the eastern United States comprises 12 species, which are divided into two species groups, the broad-headed and narrow-headed mute turtles. Their closest relatives are the ornamental tortoises and tortoises , with which they form the Chrysemys complex (named after the genus of ornamental tortoises). The diamond turtles ( Malaclemys ) living in the brackish water of the river deltas had a common ancestor with the mute turtles. Thus, the system is a sister taxa .
features
Mute turtles have greenish to black skin covered with light yellow to orange lines. The olive-green to dark-brown back armor ( carapace ) is flat and has a conspicuous keel along the center line. In all species except for the false map mute turtle ( Graptemys geographica ), this keel is shaped into more or less prominent humps on the first three vertebral shields, depending on the species. The rear edges of the armor are also jagged. The belly armor ( plastron ) is light yellow and has dark markings in some species. Although this genus includes several species that remain small, some mute turtles reach a shell length of almost 30 centimeters.
habitat
Mute turtles are found mainly in calcium-rich rivers with moderate to strong currents, depending on the species. The banks should be covered with thick vegetation and weed below the water level. Tree trunks or stones have to protrude from the water as places in the sun, as mute turtles prefer to seek out places surrounded by the water.
height
The maximum body size of some broad-headed species is 30 centimeters carapace length. Some adult males of narrow-headed species, however, grow to just 8 centimeters.
Gender differences
In addition to the primary gender characteristic of the different position of the cloaca , which is typical for turtles, the difference in size between males and females is particularly noticeable in mute turtles. Females sometimes grow to three times the length of their male counterparts. As a result, the females occupy a separate ecological niche in their biotope for a large part of the year . They live mainly in the deep areas in the middle of the river, whereas young animals and males inhabit the bank zones. In addition, the tail of female turtles is significantly thicker than that of males. Adult males, on the other hand, have much longer claws.
Life expectancy
In the absence of more precise statistics, observations of individual animals in captivity suggest that mute turtles can live to be around 60 years old.
Way of life
Their way of life is similar to that of all tortoises (see there ). They spend the day looking for food and sunbathing to regulate their body temperature. As soon as the temperatures remain permanently below 20 ° C, the animals begin to hibernate, although there are large differences due to their geographical origin. While they fall into a rigidity in the northern range at temperatures below 10 ° C, they remain moderately active in the south during winter.
nutrition
Mute turtles, with their powerful jaws, are often specialized in eating snails , but otherwise consume many types of animal food, such as fish , mollusks and insects . Vegetarian food complements your menu.
The food intake takes place exclusively in the water. However, it was observed that individual animals drew food from the land into the water.
Reproduction
In autumn and spring the males and females seek mating. After successful fertilization, the females remain fertile for several years. They lay soft-shelled eggs in spring, often in four clutches per year, around four eggs depending on the species. Preferred egg-laying sites are sunny bank zones with a slightly sandy bottom well above the water surface. The pregnant female seeks out these spots early in the morning or when it gets dark for oviposition (laying eggs). There she digs a bottle-shaped pit, which she carefully closes after laying eggs so that it can no longer be distinguished from its surroundings. The eggs are incubated for around three months. The sex of the young depends on the incubation temperature, with a species-specific value of over 28 ° C often producing females.
Systematics
Broad-headed species
The broad-headed mute turtles grow larger than the other species. They are mainly found in grassy, calm stretches of river with opportunities to sunbathe on stones or tree trunks protruding from the water.
- Barbour's mute turtle ( Graptemys barbouri Carr & Marchand, 1942)
- Escambian mute turtle ( Graptemys ernsti Lovich & Mccoy, 1992)
- Map mute turtle also map turtle ( Graptemys geographica (Le Sueur, 1817))
- Pascagoula mute turtle ( Graptemys gibbonsi Lovich & Mccoy, 1992)
-
Ouachita mute turtle ( Graptemys ouachitensis Cagle, 1953)
- Ouachita mute turtle ( Graptemys ouachitensis ouachitensis Cagle, 1953)
- Sabine bump turtle ( Graptemys ouachitensis sabinensis Cagle, 1953) - sometimes referred to as separate species Graptemys sabinensis construed
-
False map mute turtle ( Graptemys pseudogeographica (Gray, 1831)) - both subspecies are often kept in terrariums
- Missouri mute turtle ( Graptemys pseudogeographica pseudogeographica (Gray, 1831))
- Mississippi Mute Turtle ( Graptemys pseudogeographica kohnii (Baur, 1890))
- Jewelery mute turtle also Alabama mute turtle ( Graptemys pulchra Baur, 1893)
- Graptemys pearlensis Ennen, Lovich, Kreiser, Selman & Qualls, 2010
Narrow-headed species
The narrow-headed Map turtles are among the smallest turtles in general. They inhabit chalk-rich river sections with sometimes considerable currents. The possibility of sunbathing on stones or tree trunks protruding from the water must be guaranteed.
The first three species have evolved from a species that resembled the modern mute turtle after the last ice age .
- Yellow-spotted mute turtle ( Graptemys flavimaculata Cagle, 1954)
-
Black- buttoned mute turtle also known as black- bumped mute turtle ( Graptemys nigrinoda Cagle, 1954)
- Black- buttoned mute turtle also known as black-
- Delta black- buttoned mute turtle also known as southern black- bumped mute turtle ( Graptemys nigrinoda delticola Folkerts & Mount, 1969)
literature
- Carl H. Ernst, Jeffrey E. Lovich, Roger W. Barbour: Turtles of the United States and Canada. Smithsonian Books, New York 2000, ISBN 1-56098-823-1
