Geometric tortoise
Kingdom
Phylum
Subphylum
Class
Order
Suborder
Superfamily
Family
Genus
SPECIES
Psammobates geometricus
Weight
270-600
9.5-21.2
goz
g oz 
Length
120
5
mminch
mm inch 

The geometric tortoise is a critically endangered species of tortoise and one of three members of the genus Psammobates. It is found in a very small section in the South-Western Cape of South Africa.

Di

Diurnal

He

Herbivore

Fo

Folivore

To

Torpor

Zo

Zoochory

Te

Terrestrial

So

Solitary

Ae

Aestivation

No

Not a migrant

G

starts with

Appearance

It has a very strong, black and yellow patterned carapace, used for defence against predators. The patterns are arranged in ray-like markings and help the tortoise blend in with its environment. From a birds eye view the shell has geometrical symbols on it thus giving it its name. This tortoise is very small, and a full grown tortoise can only reach about 5 to 6 inches in diameter. The tortoise is one of the rarest species of tortoise of earth, only about 2,000 to 3,000 are alive today. However, because of its cryptic coloration and lack of activity, it makes it hard to create an accurate estimate of the population size.

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While it shares much of its superficial outer appearance with its relatives in the genus Psammobates, it can be distinguished by the distinctively brightly coloured yellow stars of its shell scutes, the small nuchal and single axillary, the lack of buttock tubercles, and the only slightly upturned rear margins of the shell.

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Distribution

Geography

Continents
Countries
Biogeographical realms

The geometric tortoise is naturally restricted to the far south-western corner of the Western Cape Province, South Africa. It used to occur as far north as Piketberg, as far south as Gordons Bay and eastwards into the Breede River valley. The habitat type of geometric tortoise is known as the renosterveld, which is located at the extreme southwestern part of the Western Cape Province of South Africa. The renosterveld forms part of the Fynbos Biomes, a vegetation zone characterized by a Mediterranean climate. There is a fusion of heathlands and shrublands with beginning and ending points hard to distinguish. Shrublands can then be further broken down into strandveld, coastal renosterveld and intercoastal renosterveld.

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The geometric tortoise is able to have specific dietary preferences, adaptation to wet habitats and topographical factors to survival in the habitat. The distribution range of the geometric tortoise lies within a winter rainfall area, which has 350–600 mm annual precipitation. The agriculture utilization and urban development of the renosterveld are the major factors responsible for the massive decline on the number of tortoises. The destruction of renosterveld reduced the habitat of geometric tortoises to less than 3% of its original size, which has only 4000-5000 hectares remaining. Namely food, cover, nesting and the ability to move around in the habitat are four main biological factors, which are important for the survival of geometric tortoises in their habitat. Geometric tortoises prefer low-lying and well-drained areas, which have a higher percentage of shrub cover and canopy cover at 50 cm above ground level.

The last population in Cape Town died out in the tiny Harmony Flats Reserve. The species was believed to be extinct in the 1960s, but a surviving population was discovered in 1972 and it now occurs in three isolated pockets where it is conserved. A population in the Ceres valley, one in the Tulbagh-Worcester valley, and a group surviving on the coastal lowlands to the southwest.

These colourful tortoises live only in lowland fynbos and renosterveld vegetation, meaning that their populations are easily isolated by mountains which they cannot cross.

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Habits and Lifestyle

They are said to aestivate in the months of June through September, or when their natural environment is not normal, or when in captivity. Little is known about their reproductive behaviour. When the female is ready to lay eggs, she digs a hole in the ground and covers it with grass or other vegetation. The geometric tortoise tends to feed during cooler parts of the morning and afternoon. They tend to be shy and seek shelter when they notice observers.

Seasonal behavior

Diet and Nutrition

The geometric tortoise's diet consists mainly of the leaves, geophytes, flowers, and shoots of a wide range of indigenous fynbos and renosterveld plant and grass species. Some of its more common food plants include Crassula ciliata, Oxalis species, local geophyte species, such as Cyanella hyacinthoides, Babiana angustifolia and Lachenalia contaminata ; as well as a variety of grass species such as Themeda triandra, Briza maxima, Cynodon dactylon, Ehrharta calycina, Pentaschistis curvifolia and Eragrostis curvula. A failure to have the full range of these, and other specific local plant species, means that the geometric tortoise soon dies when taken out of its natural habitat or kept in captivity. The specific diet, together with climate, humidity and soil differences, are the principal reasons why the species does not survive for long outside of its habitat. It also means that the geometric tortoise is restricted to south-western Cape alluvial fynbos and shale renosterveld vegetation types. The geometric tortoise consumes at least 14 plant species as food, which includes 64% of Aspalathus species, 60% of Oxalis species and 66% of Berkheya species occur in West Coast renosterveld. Since the distribution range of geometric tortoise lies within a winter rainfall area, the annual grasses, geophytes and other herbaceous taxa are important food items during winter. During the summer, the annual green component is reduced and therefore the perennial grass, shrub and succulent components would serve geometric tortoise as the major food resource. Food sources tend to have a higher concentration of iron and had lower failure load and tensile strength than non-food plants. When eating the tortoise uses a grab and pull method that tends to be used more in larger herbivores. They take small bites that increase surface area to be exposed to enzymes making digestion easier.

Mating Habits

PREGNANCY DURATION
120 to 210 days
BABY CARRYING
2 to 8

References

1. Geometric tortoise Wikipedia article - https://en.wikipedia.org/wiki/Geometric_tortoise
2. Geometric tortoise on The IUCN Red List site - https://www.iucnredlist.org/species/18398/173894530

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