Category Archives: Reptiles

Galapagos Giant Tortoise (Geochelone nigra)

Volcan-Alcedo-tortoise-in-habitat

  • Name: Galapagos giant tortoise
  • Latin: Geochelone nigra
  • Classification: Reptile
  • Origin: Galapagos Islands
  • Lifespan: 100+ years

Taxonomy

  • Kingdom: Animalia (Animals)
  • Phylum: Chordata (Vertebrates)
  • Class: Reptilia (Reptiles)
  • Order: Testudinidae (Tortoises)
  • Family: Testudinidae (Terrestrial tortoises with high domed carapace and elephantine feet)
  • Genus: Chelonoidis (Found in S.America and the Galapagos Islands)
  • Species: Geochelone nigra (Galapagos giant tortoise)

Appearance

  • Height: 4ft (1.2m)
  • Weight: 475lbs (215kg)

The Galapagos giant tortoise is the largest chelonian in the world and has around 12 subspecies, dotted along the length of the Galapagos Islands. There are variations among size and shape however, two main morphological forms exist – those with a domed carapace and those known as ‘saddle-backed’.

The domed tortoises are usually larger in size and do not have the upward thrust at the front of the carapace. They tend to live on larger and higher islands where forage is abundant and easily available.

The ‘saddle-backed’ tortoises evolved on arid islands and in response to the lack of available food during periods of drought. The front of the carapace angles upward which allows the tortoise to extend the head higher to reach vegetation.

Saddle-back carapace
Saddle-back carapace
Domed carapace
Domed carapace

Relatives

Listed below are the known subspecies of the Galapagos giant tortoise.

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  • Abingdon Island Tortoise (saddle-backed) (C.n.abingdoni) -EXTINCT-
  • Volcan Wolf Tortoise (saddle-backed and domed) (C.n.becki) -VULNERABLE-
  • Chatham Island Tortoise (saddle-backed and domed) (C.n.chathamensis) -VULNERABLE-
  • James Island Tortoise (domed) (C.n.darwini) -ENDANGERED-
  • Duncan Island Tortoise (saddle-backed) (C.n.duncanensis) -CRITICALLY ENDANGERED-
  • Sierra Negra Tortoise (domed) (C.n.guentheri) -ENDANGERED-
  • Hood Island Tortoise (saddle-backed) (C.n.hoodensis) -CRITICALLY ENDANGERED-
  • Volcan Darwin Tortoise (domed) (C.n.microphyes) -VULNERABLE-
  • Florena Island / Charles Island Tortoise (domed) (C.n.nigra) -EXTINCT-
  • Indefatigable Island Tortoise (domed) (C.n.porteri) -ENDANGERED-
  • Volcan Alcedo Tortoise (domed) (C.n.vandenburghi) -VULNERABLE-
  • Iguana Cover Tortoise (domed) (C.n.vicina) -ENDANGERED-

Habitat & Distribution

The Galapagos giant tortoise is endemic to the Galapagos Islands in the Eastern Pacific Ocean and the environment and climate of which varies from island to island. Generally, saddle-backed tortoises are found on hot and dry islands with sparse vegetation, while domed tortoises live on wetter and cooler islands, with plenty of vegetation at ground level.

Galapagos_Giant_Tortoise_Range_MapDiet

Galapagos giant tortoises are herbivorous and graze on grasses, leaves and cactus, as well as poison apple, guava, water fern and bromeliad. They have an extremely slow metabolism and can survive up to a year when deprived of both food and water by breaking down body fat to produce water as a by-product.

A thirsty tortoise can drink large amounts of water in a single sitting and store it in their bladders and ‘root of the neck’ (the pericardium). On arid island, individuals lick morning dew from boulders.

Juvenile tortoises eat on average 16.7% of their own body weight in dry matter a day and have the digestive efficiency equal to that of hind-gut fermenting herbivorous mammals, such as horses and rhinos.

Behaviour

Galapagos giant tortoises are cold blooded and will spend warm mornings basking in the sun and will spend a large part of the remainder of the day, grazing in small groups. Win the evening, when the temperature cools, they will sleep partially submerged in mud or water to keep warm and during the rainy season, they will wallow in shallow pools. This tortoise is regular in its sleeping, feeding and nesting habits and will sleep for approximately 16 hours at a time. They will travel the same path to feeding sites so regularly that paths have been cut and built into the landscape by them.

This tortoise is slow moving and moves on average 0.3 km/h. When determined to reach somewhere, such as a nesting or feeding site, they can cover around eight miles in 2-3 days.

The Galapagos giant tortoise has also formed symbiotic relationships with some other residents of the islands. For example, Galapagos finches will remove ticks and other parasites from the tortoise’s skin. This keeps the tortoise healthy while providing a meal for the finch. Galapagos hawks have also been seen using the tortoise has a watch post. This allows the hawk a moving point to scout for prey from and give protection to the tortoise.

Galapagos hawk perching on Galapagos giant tortoise
Galapagos hawk perching on Galapagos giant tortoise

Reproduction

Mating can occur at any time of year although it does have seasonal peaks (between January and August). Males become territorial during the mating period and rivals will size each other up by standing tall and reaching out their necks, the tallest male being dominant and thus achieving the right to mate. In mixed populations of domed and saddle-backed tortoises, the latter have an advantage over the former. Non-dominate males have been observed attempting to mate with other males and even boulders.

Males attract females by bellowing and bobbing their heads. The Male will ram the female and nip at her legs until she draws them in. Mating can last for several hours and the male will bellow occasionally throughout. The tail, which houses the penis, is then brought to the cloaca and copulation begins. The male has a concave dip to the base of his shell, which is used to lock into place with the top of the female.

After mating, the female will travel to a nesting site, which can be several kilometers away. This site is dry, sandy and often situated near the coast. The digging of the nest is done blindly with the hind legs and the process is spread out over several days, which results in a 30cm deep hole. The female then lays a clutch of 2-16 hard shelled eggs (about the size of tennis balls) and plugs the nest with a mixture of soil, leaves and urine. The female will then leave the eggs to incubate.

The young emerge from the nest after 120-140 days and each weighs approximately 80g and measures only 6cm. The temperature of the nest can affect the male to female ratio of the clutch. Low temperatures produce more males and high temperatures produce more females. Once hatched, the young must dig themselves out of the nest which can take up to a month. Sex of the young can be determined at around 15 years of age and sexual maturity is reached at around 20-25 years old. Individuals will grow slowly and will reach their adult size at around 40 years old.

Young hood island tortoise
Young hood island tortoise

Adaptations

  1. It is believed that the Galapagos giant tortoise evolved into its large size after its ancestors arrived on the islands during a time of no predators and no competition for resources, in a process known as ‘gigantism’. This large size allows the animal to house large fat and water reserves and tolerate extreme weather.
  2. The saddle-backed shell has evolved in individuals that reside on the more arid islands of the Galapagos, the shape of which allows the tortoise to reach food situated on high branches. This shape however, leaves a large gap of vulnerable skin above the head once drawn in. This suggests that the tortoise suffered little to no predation during its evolution.
  3. The domed shell is seen on individuals living on more humid islands where there is no need to reach as abundant vegetation is found at ground level. Domed tortoises tend to be larger in size and the shell shape allows for more security when the head and limbs are drawn in. This shape suggests that there may have been significant levels of predation during its evolution.
  4. Galapagos giant tortoises generally live for up to and over 100 years, a feat of which a slow metabolism is necessary. The tortoise uses little energy in its daily routine and its metabolism is not required to process energy at a consistently high rate, allowing in the long lifespan.

Threats

Throughout the 1600’s, these tortoises were often captured and stored on whaling ships as a live source of food, as they did not have to eat regularly, so sailors did not have to spend food keeping them alive. This continued throughout the 19th century as a total of over 15,000 individuals were recorded on the logs of 105 whaling ships between the years of 1811 and 1844.

Poaching of the Galapagos giant tortoise also occurs today but at a much lower level. Juvenile tortoises are primarily under threat from introduced species, such as feral dogs, cats and rats. Goats and cattle also compete with adults for resources. Some subspecies of the Galapagos giant tortoise are now extinct, including the Abingdon Island tortoise, of which the last individual ‘Lonesome George’ passed away in 2012.

Conservation

IUCN Status: Vulnerable

The Galapagos giant tortoise is listed under Appendix 1 of CITES, which only allows trade of the animal and / or its products under exceptional circumstances, and has full protection within the Galapagos National Park which was established by Ecuador in 1959. A collaboration between the Charles Darwin Foundation and the Galapagos National Park Service have been running a programme since the 1970’s, in which staff raise hatchlings from eggs until they are able to survive predation from alien species. This project has increase the population of the critically endangered Hood Island tortoise from just 13 in the 70’s to over 1,000 in the wild.

The Galapagos Conservancy are currently carrying out a project called the Giant Tortoise Restoration Initiative and state that within the next 10 years they will:

  • “Restore tortoise populations, including those considered ‘extinct in the wild’, through a combination of in-situ management, breeding and rearing tortoises where appropriate, and repopulation of an island where tortoises are extinct through the use of an analog (closely-related species).
  • Evaluate habitat conditions and restore where necessary.
  • Improve education / outreach in service of giant tortoise conservation.”

Fun Facts

  • Male: Male tortoise
  • Female: Female tortoise
  • Young: Hatchling
  • Group: Bale, Dole, Creep
  • Charles Darwin and Steve Irwin cared for the same tortoise, a female named Harriet.
  • ‘Testidunal’ means ‘pertaining to or resembling a tortoise or tortoise shell’.
  • Roman soldiers formed rows and held shields in front or above them to shelter the unit, known as the testudo formation, which is the Latin word for tortoise.

References

Animal Corner (2003) Galapagos Giant Tortoise [Online] Available at: https://animalcorner.co.uk/animals/galapagos-giant-tortoise/ [Accessed: 3 October 2015]

Arkive (2003) Galapagos Giant Tortoise (Geochelone nigra) [Online] Available at: http://www.arkive.org/galapagos-giant-tortoise/chelonoidis-nigra/ [Accessed: 8 September 2015]

BBC Nature (2014) Galapagos Giant Tortoise [Online] Available at: http://www.bbc.co.uk/nature/life/Gal%C3%A1pagos_tortoise#intro [Accessed: 8 September 2015]

Discover Galapagos (2015) The Endangered Galapagos Giant Tortoise [Online] Available at: https://www.discovergalapagos.com/tortoise.html [Accessed: 21 October 2015]

Fernando, C (2000) Animal Diversity Web [Online] Available at: http://animaldiversity.org/accounts/Chelonoidis_nigra/#behavior [Accessed: 21 October 2015]

Galapagos Conservancy (2015) Giant Tortoises [Online] Available at: http://www.galapagos.org/about_galapagos/tortoises/ [Accessed: 3 October 2015]

Galapagos Conservancy (2015) Ecosystem Restoration: Giant Tortoise Restoration Initiative [Online] Available at: http://www.galapagos.org/conservation/tortoise-restoration/ [Accessed: 21 October 2015]

Galapagos Tortoise (2015) The Galapagos Tortoise [Online] Available at: https://edangalapagostortoise.wikispaces.com/Gal%C3%A1pagos+Tortoise [Accessed: 21 October 2015]

IUCN (2015) Chelonoidis nigra [Online] Available at: http://www.iucnredlist.org/details/9011/0 [Accessed: 21 October 2015]

National Geographic (2015) Galapagos Tortoise (Geochelone nigra) [Online] Available at: http://animals.nationalgeographic.com/animals/reptiles/galapagos-tortoise/ [Accessed: 8 September 2015]

San Diego Zoo (2010) Galapagos Tortoise, Geochelone nigra [Online] Available at: http://library.sandiegozoo.org/factsheets/galapagos_tortoise/tortoise.htm [Accessed: 8 September 2015]

Eyelash Viper (Bothriechis schlegelii)

gold eyelash viper, bothrops schlegelii, venomous, central & south america
gold eyelash viper, bothrops schlegelii, venomous, central & south america
  • Name: Eyelash Viper
  • Latin: Bothriechis schlegelii
  • Classification: Reptile
  • Origin: South America
  • Lifespan: 15-20 years
  • AKA: Eyelash Mountain Viper, Eyelash Palm-Pitviper,
  • Schlegel’s ViperEyelash Pit Viper,Eyelash Snake,Horned Palm Viper,Schlegel’s Pit Viper,

Taxonomy

  • Kingdom: Animalia (Animals)
  • Phylum: Chordata (Vertebrates)
  • Class: Reptilia (Reptiles)
  • Order: Squamata (Scaled Reptiles)
  • Family: Viperidae (Vipers)
  • Genus: Bothriechis (Venomous Pit Vipers)
  • Species: Bothriechis schlegelii (Eyelash Viper)

Appearance

  • Length: 45-75cm (18-30in)
  • Weight: 4.5-6.8kg (10-15lbs)

The eyelash viper is named for the bristly scales above its eyes and are one of the smallest poisonous snakes in Central America. They have a wide, triangular shaped head and can be yellow, green, brown or red in colouration. They have good binocular vision with vertical pupils along with large fangs which are located in the maxible and fold back when not in use. The eyelash viper is slightly sexually dimorphic as the females are bigger in size than the males; both have a prehensile tail used for locomotion through the trees.

Relatives

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  • Red Adder (Bitis rubida) -DATA DEFICIENT-
  • Saw Scaled Viper (Echis carinatus) -LEAST CONCERN-
  • Desert Viper (Daboia deserti) -LEAST CONCERN-
  • Rock Viper (Vipera raddei) -NEAR THREATENED-

Habitat & Distribution

The eyelash viper can be found inhabiting densely wooded, sea level forests, wooded cloud and montane forests and rainforests. They are arboreal and their local range is close to a source of water. They can be found in the canopy, in vine tangles and shrubbery.

Their global range extends from the south of Mexico, through Central America and down to Colombia, Ecuador and western Venezuela.

Map of Distribution of the Eyelash Viper
Map of Distribution of the Eyelash Viper

Diet

Adult eyelash vipers have a varied diet which includes small mammals, birds, nestlings, lizards and frogs (juveniles feed primarily on frogs). They are a typical ambush predator, can strike quick enough to capture hovering hummingbirds and kill by injecting hemotoxic venom into their prey.

These snakes are also known to return to selected ambush sites every year in time for the spring migration of birds. Studies have also indicated that ambush snakes can learn to improve the accuracy of their strikes over time (Webb et al 2001).

Eyelash vipers have also been known to partake in ‘caudal luring’ in which they move their prehensile tail in worm-like motions to encourage potential prey to move within striking distance.

Behaviour

The eyelash viper is largely nocturnal, arboreal and generally solitary. They are not known to be an aggressive serpent but will strike if harassed. Like most snakes, they routinely ‘flick’ their tongue in order to sense chemical changes in the air. The eyelash viper is an elusive animal and as such not much is known about the communication between individuals.

Reproduction

Eyelash vipers used the chemical sensing pits located on their heads to find potential mates. As part of courtship the males will partake in a ‘dance of the adders’ as competition for females, in which they will face one another in an upright position. They will then entwine with each other, trying to push the other’s head to the ground. This is typically a non-dangerous sport as biting does not occur and may continue for many hours.

Eyelash vipers will reproduce throughout the year in warm environments and the act of mating occurs at night. One fertilised, the females will incubate the eggs internally for approximately six months. These snakes are ovoviviparous, meaning the eggs will hatch inside the body where the young will complete their development. The brood size ranges from 2-20 young and they measure 15-20cm at birth. After birth, the mothers will invest very little time in raising the young as they are born to be immediately independent. The young will reach sexual maturity at 2 years of age.

Young Eyelash Viper
Young Eyelash Viper

Adaptations

  1. The ‘eyelashes’ of the viper breaks up the outline among the foliage and aids its camouflage.
  2. The eyelash viper has complex structures known as pit organs located in their heads. These are heat sensitive organs and help to identify the direction of potential prey, very useful for the snake when hunting at night.
  3. This snake has a prehensile tail which is used for locomotion through the trees. It also uses is for caudal luring, in which it will wiggle it in a worm-like motion to encourage prey to move within striking distance.
  4. The eyelash viper has rough scales which provide protection from rough branches and offer a ‘Velcro-like’ grip on the tree branches.

Threats

The eyelash viper suffers habitat loss from increased deforestation which is carried out for timber, agriculture and urbanisation. They are also often collected from the wild to stock the pet trade. Its natural predators include large mammals, other snakes and large raptors.

Conservation

IUCN Status: Not Evaluated

The eyelash viper is not considered a threatened species in any way and was removed from the CITES Appendix III in 2002.

Fun Facts

  • Male: Male snake
  • Female: Female snake
  • Young: Hatchling, Snakelet
  • Group: Bed, Nest, Pit
  • Has been inadvertently been sent throughout the world in banana shipments.
  • Was named after the German ornithologist, Hermann Schlegel.
  • There is a myth on some areas of South America, that the eyelash viper will wink, flashing its eyelashes at a victim, following a venomous strike.
  • It is one of the most common arboreal vipers collected and kept in captivity.

References

Bothriechis schlegelii [Online] Available at: http://en.wikipedia.org/wiki/Bothriechis_schlegelii [Accessed: 13 January 2014]

Bothriechis schlegelii Eyelash Viper [Online] Available at: http://animaldiversity.ummz.umich.edu/accounts/Bothriechis_schlegelii/ [Accessed: 14 January 2013]

Eyelash Viper [Online] Available at: http://www.theanimalfiles.com/reptiles/snakes/viper_eyelash.html [Accessed: 13 January 2014]

Eyelash Viper [Online] Available at: http://www.bbc.co.uk/nature/life/Bothriechis_schlegelii [Accessed: 13 January 2014]

Fact Sheets [Online] Available at: http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Eyelashpalmpitviper.cfm [Accessed: 13 January 2014]

Golden Eyelash Viper [Online] Available at: http://winghamwildlifepark.co.uk/animal/golden-eyelash-viper [Accessed: 14 January 2014]

Adder (Vipera berus)

Adder amongst heather

(http://www.arkive.org/adder/vipera-berus/)

  • Name: Adder
  • Latin: Vipera berus
  • Classification: Reptile
  • Origin: Europe
  • Lifespan: 15 years
  • AKA: Common European adder, common viper

Taxonomy

  • Kingdom: Animalia (animals)
  • Phylum: Chordata (vertebrates)
  • Class: Reptilia (reptiles)
  • Order: Squamata (scaled reptiles)
  • Family: Serpentes (snakes)
  • Genus: Vipendae (vipers)
  • Species: Vipera berus (adder)

Apperance

  • Length: Male=60cm Female=75cm
  • Weight: Male=50-60gm Female=80-100gm

The adder has a distinct ‘V’ or ‘X’ marking on its head and have vertically slit pupils. They can be creamy white to rusty brown and have a long black diamond pattern running along their back.
The females tend to be larger than the males and have a brown, yellow or brick red background colouration, while the males are usually white or grey.

Male-adder-curled-up-on-moss-
Male adder
Adder-coiled-up-
Female adder

Relatives

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  • Black asp (Vipera aspis atra) -VULNERABLE-
  • Desert viper (Macrovipera deserti) -NEAR THREATENED-
  • Palestine saw-scaled viper (Echis coloratus) -NOT EVALUATED-
  • Horned bush viper (Atheris ceratophora) -VULNERABLE-  

Habitat & Distribution

The adder prefers rough and open countryside and can often be seen in woodland edge habitats. They are the most frequently seen of the three British snakes as they are less likely to disappear into the undergrowth.

The adder is the most northerly distributed reptile and can even be found within the edges of the Arctic Circle. They live across Europe, as east as the mountains of Russia and as south as the Mediterranean. The UK is its westerly extreme, although they are absent from Ireland.

Map showing the distribution of the Adder taxa

(http://www.bbc.co.uk/nature/life/Vipera_berus)

Diet

The diet of the adder is very varied and can include voles and other small rodents, lizards, bird’s eggs, insects and snails. To hunt, they strike at the prey, injecting a lethal dose of venom, and then they wait patiently for it to die. It will then find the prey by following its scent and then begin the lengthy swallowing process.

Like other snakes, the adder will swallow its prey whole. The jaw bones can move independently as they are connected by extensible connective tissue, also the ribs are not joined at the bottom, allowing them to open right up. This allows the adder to eat prey much larger than the width of its head. The teeth are also designed to grip the prey while it is being swallowed. The adder also has a very powerful digestive fluid which can digest flesh and bones almost completely. Only the hair and teeth pass through intact.

Behaviour

In the north of their range, adders tend to be diurnal, and near the south, they are more crepuscular. They tend to be terrestrial but they will climb up banks and into low bushes to bask or search for prey.

They are the only venomous snake in Britain but will rarely attack. Instead, they rely on their camouflage to keep them hidden and will disappear into the undergrowth if they feel the vibrations of a threat approaching. The venom of the adder is quite strong, however, they do not inject a large amount at one time nor do they strike repeatedly which makes them less of a risk to humans.
In Britain, the males will hibernate for 150 days and the females for 180 days. On mild winter days, the adder will travel across the snow to patches where it has melted to bask. 15% of adults and 30-40% of juveniles will die during hibernation.

Reproduction

Courtship and mating of the adder takes place around April-May and are so preoccupied with such that they will often completely ignore the presence of a human. The males will circle the female in jerky movement and flicking his tongue all over her body. This allows the male to determine whether she is receptive. Mating takes place in dense undergrowth and can take up to two hours.

After mating, the male will ‘mate-guard’ the female, staying close to her side, this insures that no rival males mate with her. Intruding males will be challenged. They begin by sizing each other up, by moving parallel to each other. During combat, the males will intertwine their bodies, attempting to force the head of their opponent to the ground. This is known as the ‘Dance of the Adders’ and can often last several minutes. The defeated male will shoot away and the victor will return to the female.

Adders are viviparous, giving birth to live young, and the eggs develop and hatch within the body of the female. The young adders are born in mid-summer. Around 8-10 babies are born with an average length of 6-7 inches. The adder has a slow reproductive rate, only giving birth once every other year.

Immature female adder
Immature female adder

(http://www.arkive.org/adder/vipera-berus/image-A7212.html)

Adaptations

  • Like other snakes, the jaws of the adder can move independently of each other and the ribs are not connected at the bottom allowing it to open is mouth incredibly wide. This allows the adder to eat food many times the width of its head.
  • The adder has excellent camouflage. The dark diamond pattern running along its back keeps it invisible in the undergrowth. The adder uses this as its primary method of avoiding detection by predators.
  • Adders are almost deaf and would not be able to hear an approaching threat. They can however, feel vibrations in the earth. They will take off of they feel the vibrations of an approaching animal.
  • The adder has very powerful venom which it uses to kill its prey. It is not fatal to humans however medical help is given soon after an attack.

Threats

The adder has a few predators including birds of prey, such as the buzzard, and other adult snakes. Also, they can be killed and eaten by rodents during hibernation. They suffer habitat loss in a number of areas throughout Europe because of scrub encroachment, development, agriculture and afforestation.

Outside of Britain, they are collected for the pet trade and in Romania, they are killed for illegal collection of their venom.

Conservation

  • IUCN Status: Least Concern

In the UK, the adder is protected under the Wildlife and Countryside Act 1981 which makes it illegal to kill, injure, harm or sell the adder. They are also classified as a priority species under the UK Biodiversity Action Plan, a proposed action being to educate the public in order to dispel fears and reduce deliberate persecution.

They are listed on Annex II of the Bern Convention which aims to conserve wild flora and fauna in their natural habitats. They occur in protected areas throughout their range and are protected by national legislation in many countries.

Fun Facts

  • Male: Male snake
  • Female: Female snake
  • Young: Hatchling
  • Group: Nest
  • Snakes do not have eyelids.
  • Snakes are found on every continent, except Antarctica.
  • Snakes can smell with their tongue.
  • There are 3,000 different species of snake.
  • Snake have flexible jaws, allowing them to eat prey much larger than themselves.

Gharial (Gavialis gangeticus)

Gharial, view from behind

(http://www.arkive.org/gharial/gavialis-gangeticus/image-G113436.html)

  • Name: Gharial
  • Latin: Gavialis gangeticus
  • Classification: Reptile
  • Origin: India
  • Lifespan: 50-60 years

Taxonomy

  • Kingdom: Animalia (animals)
  • Phylum: Chordata (vertebrates)
  • Class: Reptilia (reptiles)
  • Order: Crocodilia (crocodiles)
  • Family: Gaviadlidae (gharial)
  • Genus: Gavialis (gharial)
  • Species: Gavialis gangeticus (gharial)

Apperance

  • Length: (Female) 2.5-4 meters, (Male) 3-6 meters
  • Weight: 150-250kg

Gharials are long and slender animals. Their colouring is light olive tan with dark blotches or bands running down their body and tail. Their webbed feet and strong tail make it an excellent swimmer; however their limbs are weak, keeping them from making extensive overland journeys that their fellow crocodilians make. Gharials are the largest of crocodiles.

The males have a large, bulbous mass on the end of their snout known as the ghara. This is the Indian word for ‘pot’. The function of the ghara is unknown but it is thought to produce a loud buzzing noise when it vocalizes.

The eyes are set high on its head and its jaws are equipped with sharp, pointed teeth that point forward and slightly outward. They have 54 teeth on its upper jaw and 48 on the lower. They have a tough hide which is sought after by hunters and poachers. Their legs are proportionally longer than other crocodiles but they are clumsy on land. Their leg musculature doesn’t allow them to raise their body or tail off the ground. However, they can belly-slide quite quickly.

Relatives

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  • Saltwater crocodile (Crocodylus porosus) -LEAST CONCERN-
  • Cuban crocodile (Crocodylus rhombifer) -CRITICALLY ENDANGERED-
  • Dwarf crocodile (Osteolaemus tetraspis) -VULNERABLE-
  • Orinoco crocodile (Crocodylus intermedius) -CRITICALLY ENDANGERED-

Habitat & Distribution

Gharials are adapted to live in riverines, in the calmer areas of the deep, fast flowing rivers. Their physical attributes do not make it good for moving about on land. In fact, the only reason it leaves the water at all is to bask in the sunlight and to nest in the sandbanks of the river.

In India, the Gharial can be found living at the National Chambal Sanctuary, the Katarniaghat Wildlife Sanctuary, the Son River Sanctuary and the Satkosia Gorge Sanctuary. In Nepal, they live at the Chiwan National Park and the Bardia National Park.

Due to poaching, they are now extinct in the Indus River of Pakistan, the Brahmaputra or Bhutan and Bangladesh and the Irrawaddy River of Myanmar.

(http://www.theanimalfiles.com/reptiles/crocodiles_alligators/gharial.html)

Diet

The diet of the Gharial changes as it grows from a juvenile to an adult. The juveniles eat a variety of invertebrate prey such as insects, plus smaller vertebrates such as frog, but primarily they eat small fish.

The adults are fish eaters, for which their jaws and teeth are perfectly adapted. The thin, narrow shape of the snout gives it low resistance in the water. Also, their teeth are perfectly suited to keeping grip on struggling prey, such as slippery fish.

Behaviour

Like most crocodiles, Gharials get along well with each other and like to live in groups. They stay in the water most of the time, occasionally coming out to bask in the shore. At the slightest sign of threat, they will dive back into the safety of the water. On especially warm days, the Gharial will open its mouth wide to cool off. This serves the same purpose as panting does for a dog.

The mating season for the Gharial arrives in December and January. During this time the adult males begin fighting each other to set up territories in the shallow water. Two males will lie side by side, life their heads up out of the water and being pushing each other with their snouts. The winner is the one who can topple the other over. Sometimes, the fights can become more violent, where the males being to bite each other.

A male with a good sized territory can attract several females to mate with. The ghara is also important during mating season. It produces a loud buzz which is attractive to females and warns other males to stay away.

Reproduction

A female gharial will lay her eggs sometime between March and May. They dig their nests in the dry ground on the bank of the river at least 5ft (1.5m) above water level. Females are very fussy about the location of their nests and will change their minds several times, even after they have begun to dig. They are territorial over their nests and stay near most times, defending from predators if necessary, however, they will share beaches will other females.

After digging a hole in the sand, the female will lay her eggs inside and carefully cover them. The smallest females lay as few as a dozen eggs and many first-time mothers lay eggs that never hatch at all. The largest females will lay almost 100 eggs.

A typical gharial egg is 2.2inches (5.5cm) wide, 2.4inches (8.6cm) long and weighs 5.5ounces (156g). The eggs will hatch around 53-92 days after being lain. Eggs in the warmest nests usually tend to hatch sooner than eggs in cooler ones. The temperature of the nest also affects the gender of the young. Warm nests produce more males, and cool nests produce more females.
After the babies have hatched the mother will help them out of the nest and then she, and even possibly the father, will watch over them. However, many of the females young do not survive, despite this care. The eggs are often eaten by animals such as pigs, hyenas, monitor lizards and even by humans, and the babies are hunted after by birds and turtles. Also, the young are born during the monsoon season and can drown in floods.

Females can be ready to mate when they are at least 8 years old and are 10ft (3m) long. Males however must wait till they are 15 years old and about 11.5ft (3.5m) long until they can mate.

Adaptations

  • The gharial’s jaw is long and slender with interlocking teeth. This provides speed and grip for catching slippery fish.
  • The gharial’s tail is flattened on the sides. This helps the gharial to be quick underwater.
  • The eyes and nostrils of the gharial are positioned high on the head. This means that it can stay completely submerged underwater whilst being able to see and breathe.
  • The male gharial has a growth on the end of his nose known as a bulbous. This organ makes a low rumbling noise which is thought of as a way of attracting females.

Threats

Agriculture: In India, riverbanks are being taken over for agricultural use. This is limiting the nesting and basking areas of gharials.

Sand mining: Sand extraction is allowed outside of protected areas, but continues along the riverbanks of the National Chambal Sanctuary. This destroys areas required by the gharials for nesting and basking.

Livestock grazing: Cattle, water buffalo and goats graze along the riverbanks of gharial habitat areas which cause destruction to gharial nests.

Disturbance: Gharials are shy and wary creatures. So human activity and livestock grazing will cause disturbance to the natural gharial activity of nesting and basking, and drive them from their habitats.

Pollution and Siltation: Polluted Rivers damage the fish stocks that the gharials depend upon, as well as threatening the other species of animals and plants within the river ecosystem.
Dams, barraged and irrigation projects: These man-made dams change the courses and water levels of the rivers. In some areas, it drastically lowers the river level and makes former habitats inhospitable for gharials. In other areas, it makes the water level so high that the rivers flood and washes gharials away from protected areas. This is thought to be a significant source of mortality in hatching gharials.

Fishing and Turtle Poaching: Gharials are often caught in fishing nets. Their snouts can become entangled in the nets, and then drown as they can’t resurface to breathe. Sometimes a trapped gharial can break free but the nets remain tangled around their snouts and the gharial will starve to death. Often, when gharials are found entangled in fishing nets their heads or snouts are cut off by fishermen. A gharial can survive for many months without a snout but will eventually die of starvation.

Conservation

  • IUCN Status: Critically endangered

The most successful group dedicated to helping the gharial numbers increase is the Gharial Conservation Alliance (GCA). They carry out a number of different activities including scientific population surveys, captive, breeding, wild restocking programmes and education, awareness and government lobbying. All created to help the numbers of gharials increase and to protect existing ones.

In 1975, Project Crocodile was set up with the Indian Government and the United Nations Development Programme Food and Agriculture Organization (UNDP-FAO). 240km of habitat was set aside in 6 gharial sanctuaries, and 16 rearing centres were set up for ‘head-starting’ programmes.

In 1975-1992, 5,000 head-started gharial release.

Fun Facts

  • Male: Male Crocodile
  • Female: Female Crocodile
  • Young: Hatchling, Irwin
  • Group: Float, Bask, Congregation, Nest
  • The gharial is the longest crocodilian species.
  • The snout becomes longer and thinner as the gharial gets older.
  • They have 54-58 teeth on the upper jaw and 50-52 on the lower jaw.
  • Humans are the main predator of the gharials.
  • Gharials are also known as Gavial, Indian Gharial, Indian Gavial, Fish-eating crocodile and Long-nosed crocodile.

Komodo Dragon (Varanus komodoensis)

File:Komodo dragon with tongue.jpg

(http://en.wikipedia.org/wiki/File:Komodo_dragon_with_tongue.jpg)

  •  Name: Komodo dragon
  • Latin: Varanus komodoensis
  • Classification: Reptile
  • Origin: Asia
  • Lifespan: Up to 50 years

Taxonomy

  • Kingdom: Animalia (animals)
  • Phylum: Chordata (vertebrates)
  • Class: Reptilia (reptiles)
  • Order: Squamata (scaled reptiles)
  • Family: Varanidae (carnivorous lizards)
  • Genus: Varanus (monitor lizards)
  • Species: Varanus komodoensis (Komodo dragon)

Appearance

  • Length: Male – 8-10ft (2.4-3m) Female – Up to 8ft (2.4m)
  • Weight: Male – 300-500lbs (136-226kg) Female – Up to 200lbs (90kg)

The Komodo dragon is the heaviest lizard in the world. They are dull black, grey or green in colour. Their heads look similar to snakes, with a rounded snout and a forked tongue. They have a heavy tail which can be the same length as its body. They also have bowed legs with long, curved claws on all four feet.

Young Komodos differ in appearance as they are dark in colouration but have patches of yellow, white, green and black on their scaled skin.

Relatives

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  • Bengal monitor (Varanus bengalensis) -LEAST CONCERN-
  • Lace monitor (Varanus varius) -LEAST CONCERN-
  • Yellow-headed water monitor (Varanus cumingi) -LEAST CONCERN-
  • Yellow monitor (Varanus flavescens) -LEAST CONCERN-

Habitat & Distribution

Populations of the Komodo dragon can be found on a few volcanic islands of the Lesser Sunda group such as Komodo, Rintja, Pandar and Flores. It mainly occurs in the harsh climates of tropical savannah forests where there is very little rainfall and temperatures can reach 82’F (27’C). Komodo dragons can range from the beaches to ridge tops of its islands homes in search of food.

Map showing the distribution of the Komodo dragon taxa

(http://www.bbc.co.uk/nature/life/Komodo_dragon)

Diet

Komodo dragons are carnivorous and eat mainly carrion. Their diet can include invertebrates, other reptiles, birds and their eggs, goats, deer, water buffalo, feral pigs and other reptiles. They can also display cannibalistic behaviour and eat young Komodo dragons. The young Komodos will eat insects, eggs and small lizards and mammals.

These dragons have sharp teeth that resemble that of a shark. Any animal that escapes the jaws of a dragon will only die later on from blood infection as its saliva is full of bacteria. It has also been recently discovered that these lizards have a venom gland in their jaw, however, it has not yet been confirmed if their bites are venomous.

Large prey will be torn into chunks by the dragon when eating it. Smaller prey (such as goats) can be eaten whole due to their loosely articulated jaws, flexible skulls and expandable stomachs. It will take a komodo dragon 10-20 minutes to swallow a small mammal during which can breathe through a small tube under the tongue leading to the lungs. A dragon can eat as much as 80% of its body weight in one sitting. Typically the vegetable content of the stomach and intestines are left untouched.

After eating, the Komodo dragon will sit in a sunny spot to speed up digestion. If left undigested for long, food in the stomach can rot and poison the animal. Their slow metabolism means they can survive on as little as 12 meals a year. After digestion has been completed, the dragon will regurgitate a pellet made up of horns, hair and teeth.

Occasionally, the Komodo dragon will consume human corpses dug from shallow graves. This has caused the villagers of Komodo to mode their graveyards from sandy to clay ground and pile rocks on top of the individual graves to deter the lizards.

Behaviour

Komodo dragons can be active during day or night and are solitary, gathering together only to breed or at large meals. They can sprint at speeds of 20kph for short distances, are good swimmers (can dive 4.5m deep) and can use their large claws to climb trees.

These dragons use their powerful forelegs and claws to dig holes for shelter, around 1-3m wide. By resting in these holes, they can maintain body heat during the night and reduce sunbathing time in the morning. The komodo dragons tend to take shelter during the hottest part of the day. Their hiding places located within the reach of a sea breeze, little vegetation and tend to have the inhabitants dung scattered about. These hiding places are also excellent places to wait for deer and strike from.

Reproduction

For the Komodo dragons, mating occurs between May and September. During this time, the males will fight over females and territory by scrapping with each other on their hind legs, the loser will eventually be pinned to the ground. Before a fight, the males have been known to vomit or defecate. The victor will then flick his tongue over the female to gain information about her receptivity.

During early courtship, the females will resist with their teeth and claws so to avoid injury, the male must fully restrain the female during coitus. Other behaviours displayed during courtship include licking and hard scratches along the back. These dragons can also be monogamous and form ‘pair bonds’, a behaviour rare in reptiles.

Clutches of eggs are laid in September and are laid in either a burrow dug into the side of a hill or in an abandoned nesting mount of orange-footed scrubfowl. The average clutch size is 20 eggs and incubation can last between 7 and 8 months.

The young hatch from their shells using an egg tooth which falls off shortly after. They are born defenceless and vulnerable to predation by animals including adults of their own kind. The young spend most of their first few years in the trees and will often roll in the faeces of other animals to deter predators. Komodo dragons take 3-5 years to mature and can have a total lifespan of up to 50 years.

Female komodo dragons are also able to reproduce sexually or asexually depending on their environmental conditions. Parthogenesis, the ability for an unfertilized egg to develop to maturity, occurs in 70% of all vertebrate species.

Adaptations

  • It has been recently discovered that the Komodo dragon has a venom gland located in its jaw. This venom rapidly decreases blood pressure, expedites blood loss and sends the victim into shock, slowing it down enough to be killed by the dragon.
  • The saliva of the komodo dragon is full of bacteria that can kill small animals and make their larger prey feel very sick. There are 50 kinds of bacteria in the dragons saliva.
  • The main food source of the komodo dragon is deer. To ensure the food source does not run dry, the komodo dragon has adapted to survive on only 1/10 of the food intake of carnivorous mammals.
  • The komodo dragon has the ability to regrow any lost teeth several times over, not unlike that of a shark.

Threats

There are around 5,000 individual komodo dragons in the world, only 350 or which are breeding females. Their population is thought to be only a fraction of what it was 50 years ago. Their main reasons for decline are habitat loss, loss of prey species and hunting.

They are susceptible to storms, fires and disease and are sought after by trophy hunters. The skins and feet are used to make novelty items. In the past, they have been trapped for sale to zoos and private collectors. Since the 1970’s, no komodo dragons have been seen on the island of Padar.

Conservation

  • IUCN Status: Vulnerable

The Komodo dragon has been protected by law since the 1930’s and has become an increasingly popular animal. This flagship species brings in over 18,000 tourists a year to the area, helping to raise funding for all the animals on the islands.

They are protected by CITIES (Appendix I) which prohibits all international trade in the animal. They are also part of an EEP breeding programme working to create an insurance population amongst zoos around the world.

Fun Facts

  • Male: Bull
  • Female: Cow, lizardess
  • Young: Hatchling, pup
  • Group: Lounge, clan
  • The komodo dragon is the largest and most powerful lizard in the world.
  • It is immune to its own venom.
  • The komodo dragon can throw up the contents of its stomach to make itself lighter when it feels the need to flee.
  • It is also called the ‘land crocodile’ by locals.

References