DIET AND LIFESTYLE
The Komodo dragon (Varanus komodoensis), a truly imposing animal, is the largest saurian in existence today. Adult males can exceed 3.5 meters and their weight can exceed 90 kg. At birth they measure 45 cm and are exclusively arboreal.
They feed mainly on carrion, but also hunt and ambush their prey, mainly invertebrates, birds and mammals. Their ferocity is tremendous, even attacking and killing indigenous people on occasion. With their long and powerful claws they grab their prey and with their teeth curved backwards they tear the flesh.
They have about 60 teeth up to 2.5 cm long. However, their jaws are not suitable for chewing, so they swallow large pieces of meat. They can consume 80% of their body weight at one sitting. After digestion, they regurgitate a mass with non-digestible parts (hair, teeth, feathers).
Thanks to their strong limbs, they build burrows 1-3 meters deep, where they rest or hide to stalk prey. In addition, and despite their large size, they are skilled swimmers and tree climbers. They are also relatively fast, being able to reach up to 20 km/h.
Their bite is extremely dangerous for two reasons: on the one hand, their saliva harbors more than 50 bacterial strains that can generate lethal infections and, on the other hand, they possess a venom that produces changes in blood coagulation, leading to hemorrhaging and hypotension. Therefore, even if the prey were lucky enough to escape an initial attack, it would probably not get very far.
Its geographic distribution is limited to the islands of Komodo, Rinca, Gili Dasami, Gili Motang and Flores, in the Indonesian archipelago. The species was on the verge of extinction due to international trade. It is currently listed as endangered according to the IUCN Red List. It is protected by Indonesian law and in 1980 the Komodo National Park was founded to contribute to its conservation.
REPRODUCTION BY PARTHENOGENESIS
In 2006 a paper was published in Nature that demonstrated the ability of this species to reproduce by parthenogenesis, an asexual reproductive mechanism. Although the females in the study lived in captivity and had no contact with males at any time, they were able to lay some viable eggs from which hatched offspring, all of them males.
The genetic study carried out on the offspring resulted in the genotype (set of genes) of the litter being identical to that of the mother. In parthenogenesis, the egg develops without being fertilized by a spermatozoon, giving rise to an individual identical to the mother. However, in the case of the Komodo dragon, the offspring are always males. The explanation lies in the fact that the sex chromosomes of the females of this species present the combination ZW (in mammalian females it is XX), while in males it is ZZ (in mammalian males it is XY). Since in parthenogenesis the male does not contribute his chromosomes through his gamete, the female chromosome will be duplicated, resulting in ZZ (male) or WW embryos, the latter being non-viable.
Parthenogenesis is known in many other animal groups (flatworms, crustaceans, insects, some fish, and even birds). It had also been recorded in some reptiles, but this study was the first to record this type of reproduction in Komodo dragons.
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Fry, B.G., Wroe, S., Teeuwisse, W., van Osch, M.J., Moreno, K. et al. (2009). A central role for venom in predation by Varanus komodoensis (Komodo dragon) and the extinct giant Varanus (Megalania) priscus. PNAS 106, 8969-8974. https://doi.org/10.1073/pnas.0810883106
Rancho Texas Lanzarote Park (2022). Dragón de Komodo. Available in: https://ranchotexaslanzarote.com/dragon-de-komodo-varanus-komodoensis/
Redacción (2020). Un dragón de Komodo hembra engendra por sorpresa tres crías sin la ayuda de un macho. La Vanguardia [online]. March 14. Available in: https://www.lavanguardia.com/cribeo/fauna/20200314/474078377697/dragon-komodo-hembra-engendra-sorpresa-tres-crias-ayuda-macho-partenogenesis-extincion.html
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