Coming in a variety of colors, such as blue, orange, green, and gray, the Komodo dragon is the largest extant lizard species. Male individuals can weigh up to 100 kg, and can grow up to 3 m (10 feet) in length. The largest individual ever recorded was 3.13 m and weighed 166 kg, although a more common weight is 70 kg. Female individuals are smaller, usually only about 1.8 m (6 feet) in length. Aside from the obvious size difference, there are no major morphological differences between the sexes (National Geographic). Despite their impressive size, they are very small when born, about 0.1 kg. The body of the lizard is long and flat, with short bowed legs. At the end of each leg are long sharp claws, which are used for both hunting and digging nests. The tail of the Komodo dragon is long and powerful (Smithsonian National Zoological Park). Much like snakes, Komodo dragons have a forked tongue they use to “smell.” This tongue is flicked out and tastes the air to detect prey, as well as which direction it is coming from.
While being impressive in size, the most interesting aspect of the Komodo dragon is its mouth. This dragon has a dorsoventrally flattened rostrum, which means it has a long, flat snout and its mouth is filled with long, curved and serrated teeth. The jaw contains several movable joints, such as the intramandibular hinge, which allows the Komodo dragon to open its mouth very wide, and quickly swallow its food (Smithsonian National Zoological Park). Despite its intimidating mouth, the Komodo dragon has a relatively weak bite force compared to other large predators (e.g. saltwater crocodiles, lions, hyenas). This bite force did correlate positively with body size, with larger individuals having a stronger bite but bite force did not correlate with mouth width (D’Amore et al, 2011). The Komodo dragon’s teeth and claws are not its main weapon however. Located within the mandible are glands that secrete powerful venom. This venom acts as both a neurotoxin and an anti-coagulant (Fry et al, 2009). The neurotoxin causes the prey to go into shock, which allows the dragon to rest after hunting without fear of the prey escaping. The anti-coagulant effect will cause the animal to bleed out very quickly, should it manage to escape. The stomach of the Komodo dragon is very accommodating, allowing up to 80% of the animal’s body weight to be consumed (National Geographic).
The sexual maturation of both male and female komodo dragons typically occurs between 5 and 7 years of age. A typical komodo dragon mating season occurs between May and August. Dominant males often engage in wrestling matches in an upright position, balancing on their tails and hind legs in order to determine courtship over a female. The winning wrestler signals the beginning of the courtship by flicking his tongue on a female’s snout and then over the rest of her body (Smithsonian National Zoological Park). Stimulation is both palpable and chemical, through skin gland secretions. Mating occurs very quickly and, due to the female Komodo dragon’s adversarial behavior, males must be able to completely restrain the female to avoid the risk of injury.
A typical Komodo dragon gestation period will last around 9 months. Subsequently, a komodo dragon will lay anywhere between 15-30 eggs in September (Ciofi, 1999).Females will lie on the nests to protect their potential offspring, but they do not care for them after they hatch. In fact, as soon as they hatch, the young will scatter and climb up trees in order to avoid being cannibalized by the mother or other dragons. The hatchlings will weigh less than 3.5 ounces and average only 16 inches in length. They will feed on a diverse diet of insects, small lizards, snakes, and birds. If they make it to five years of age, their chance of survival increases dramatically.
Female Komodo dragons are capable of having “virgin births” or parthenogenesis. This has been observed both in the wild and in captivity. This means that Komodo dragons can reproduce asexually as well as sexually (Yam, 2006). This trait has been observed in varying species of reptiles. Parthenogenesis is extremely rare among vertebrates, occurring in a mere 0.1 percent of all vertebrates. Furthermore, Komodo dragons have a unique variation in their sex determination. The presence of two identical sex chromosomes results in a male komodo dragon, while two different ones results in a female. Komodo dragon gender is determined by incubation temperature. It is believed that the ability to reproduce both sexually and parthenogenetically is a natural response resulting from the Komodo dragon’s isolated habitat. Researchers speculate that this ability enabled female Komodo dragons to establish new colonies when washed up alone on neighboring shores during storms (Yam, 2006).
Komodo dragons are solitary animals that generally meet only to reproduce and eat. They are primarily diurnal, which means they are most active during the day. They tend to be most active during the wet season. Komodo dragons prefer hot and dry places with open grassland, as well as tropical forests at low elevations. In regards to territorial behavior, there is a dominance hierarchy determined by size and sex. The largest and strongest males get first priority when eating. Males often wrestle in an upright position to determine mating and feeding orders. Hissing is a common vocalization that indicates defensive behavior and is often used during feeding, fighting, and repeatedly by females during mating season (San Diego Zoo, 2016). Additionally, the feces of a female komodo dragon emits pheromones that alert the males that they are ready to mate.
Komodo dragons are quadrupeds and possess the ability to sprint briefly at speeds of up to 20 kph. As a result, its hunting strategy relies primarily on strength and stealth. It is common for them to spend hours in a single spot, waiting for a deer, boar, goat, or other potential prey (Smithsonian National Zoological Park). Komodo dragons act as both predators and scavengers. They have venomous glands packed with toxins that lower blood pressure, cause massive bleeding, prevent clotting and induce shock in prey (National Geographic). When combined with the dragon’s serrated teeth and powerful neck muscles, this leads to huge gaping neck wounds in their prey that weakens and immobilizes them.
Young komodo dragons are exceptional tree climbers, but they tend to lose this ability after a year. It is primarily a defense mechanism to avoid being cannibalized by their mother. As Komodo dragons mature, they begin to transition into a semi-aquatic lifestyle. When hunting, komodo dragons rely heavily on their sense of smell for finding food. This is utilized through scent-detecting glands at the tips of their tongues (Smithsonian National Zoological Park).
The Komodo dragon is found only on 5 islands in the lesser Sundas region of southeastern Indonesia, including Komodo, Rinca, Gili Motang, Gili Dasami, and Flores (Jessop et al, 2004; San Diego Zoo, 2016). These islands are volcanic in origin, and covered in many habitat types, but mainly forest and savannah. Most of the Komodo dragons live on Komodo Island, from which their name is derived (Jessop et al, 2004). The temperatures during the daytime in the dry season can reach up to 35 degrees Celsius. In addition to these high temperatures, the islands can reach up to 70 percent humidity (San Diego Zoo, 2016).
Komodo dragons live in three main habitat types: coastal mangroves, open savannahs, and fragmented shade forests. Juveniles are typically arboreal, while adult dragons typically are terrestrial (Harlow et al, 2010). Most komodo dragons prefer to live in savannahs with tall grasses and bushes, where they wait to ambush prey, but they are found all across the islands. Other types of habitats they can be found in are beaches and mountaintops. Within their habitats, Komodo dragons build themselves one of three types of nests for living and egg-laying: ground nests, hill nests, or mound nests. Ground nests are deep burrows that are horizontal to the ground. Hill nests are large burrows built into the face of a hill, in one or more tiers. Mound nests are nests that were previously used by other animals (such as orange-footed scrub fowl or other dragons) that have been repurposed by Komodo dragons. These nests tend to be constructed more often within a fragmented deciduous forest than any other type of habitat (Jessop et al, 2004). Upon hatching, komodo dragons are arboreal until about 8 months of age. After 8 months of age, they leave the trees for the ground where they spend most of their time, although they are also excellent swimmers (National Geographic).
