The Common Basilisk (Basiliscus basiliscus) is a lizard found in Central and South American rainforests near rivers and streams.The basilisk is part of the corytophanid family. It is also known as the Jesus Lizard, Jesus Christ Lizard, or Lagarto de Jesus Cristo for its ability to run on the surface of water.
Taxonomy and etymology
The Common Basilisk is named for the creature of Greek mythology made up of parts of a rooster, snake, and lion which could turn a man to stone by its gaze: the Basilisk. Its generic, specific and common names all derive from the Greek basilískos (βασιλίσκος) meaning "little king". The specific epithet was given in Carolus Linnaeus' 10th edition of Systema Naturae.
Nicknamed the “Jesus Christ Lizard,” this extraordinary reptile may run on water when threatened. This spectacle can be readily witnessed; of all large lizards in Costa Rica, this species is the most commonly encountered, especially along streams and lakes. It is more numerous in the dry northwestern region of the country. Adults often bask in daylight near water when they are not foraging or resting. At night they sleep on perches close to the ground or as high as 20 m.
When startled, the Common Basilisk escapes by speeding to the nearest edge of water—and continues sprinting. The lizard runs on only its hind legs in an erect position, holding its arms to its sides. This basilisk is so adroit on water because its feet are large and equipped with flaps of skin along the toes; when moving quickly, the lizard can cross a surface of water before sinking. On water it runs an average speed of 8.4 km/h (or 5.2 mph), which is just a little slower than its speed on land. Younger basilisks can run 10 to 20 meters on water, while adults cross only a few meters before sinking. Adults do not move slowly, but they weigh more and cannot sprint for as long a time. Once a basilisk submerges, it continues swimming until it is sufficiently far from its pursuer—if the predator has followed past the bank. Although this lizard stays close to water to escape terrestrial predators, it swims only when necessary because there are aquatic animals that would be just as happy to eat the basilisk given the chance.
Range and habitat
The Common Basilisk is found throughout Central and South America usually living in low elevations, from sea level to 600 m. In Costa Rica this basilisk can be found as high as 1,200 m in some places. The species ranges from southwestern Nicaragua to northwestern Colombia on the Pacific side, and from central Panama to northwestern Venezuela on the Atlantic side. In Costa Rica it is mostly found on the Pacific side of the country. The equivalent species on the Atlantic side is the Green Basilisk, which occupies similar habitats and has similar biology. It has been introduced to Florida as a feral species.
The Common Basilisk can be distinguished from similar species within its range by its large size and the high finlike crests down its back. Males also have high crests on the head and tail. Both sexes are brown to olive, and have a white, cream or yellow stripe on the upper lip and a second stripe along either side of its body; these stripes have higher contrast in juveniles and fade as the lizards age. Hatchlings weigh a mere 2 g and are 37 to 43 mm long. Adults can grow up to two and a half feet long. Females are generally 135 to 194 and weigh half as much as males. The tails of these lizards comprise 70 to 75% of their total length: for example, on an 800 mm (or 31.5 in) long lizard, 600 mm of its length is tail.
The common basilisk has a large mouth with saw-like teeth that are on the inner sides of the jaw. They have been known to run up to 7 mph (11 km/h). While the basilisk is most known for its ability to run on water, they are also excellent climbers and swimmers; the basilisk has been known to stay underwater for up to half an hour. The average lifespan is 7 years in captivity; in the wild it tends to be less because of predators.
The Basilisk has many natural predators; large reptiles, birds, and some mammals. To avoid predators the Basilisk can conceal itself under leaves on the forest floor and can remain motionless for a long time. When the Basilisk must flee, though, its skill of running on water can help it avoid many predators.
Females lay three to four clutches of 10–20 eggs a year. Eggs hatch after about three months and the young weigh about two grams and are up to three inches long. Their outstanding camouflage allows them to remain undetected when they remain still.
Locomotion on water
The Common basilisk, along with the other members of its genus, take the nickname the "Jesus Christ Lizard" or "Jesus Lizard" because when fleeing from predators, they gather sufficient momentum to run across the water for a brief distance while holding most of their body out of the water (similar to the Biblical miracle of Jesus walking on water). Basilisks have large hind feet with scaly fringes on the sides of the third, fourth, and fifth toes. These are compressed against the toes when this lizard walks on land; but if the basilisk senses danger, they can jump into the water, opening up these fringes against the water's surface. This increases the surface area of the foot, thus allowing them to run on the water for short distances. The mechanics of this work in three steps. First there is the slap, this is the downward movement of the foot that pushes water out and away from the leg. This also created pockets of air around the foot. Next is the stroke, this is the backwards movement of the foot, which propels them forward. Next is the recovery, this is when the foot comes up and out of the water and prepares to do the slap again. Smaller basilisks can run about 10–20 m without sinking. Juveniles can usually run farther than older basilisks, while holding more of their body above the surface.
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- The Reptile Database. www.reptile-database.org.
- Robert George Sprackland (1992). Giant lizards. Neptune, NJ: T.F.H. Publications. ISBN 0-86622-634-6.
- Conant, Roger; Collins, Joseph (1991). A Field Guide to Reptiles and Amphibians Eastern/Central North America. Boston, Massachusetts: Houghton Mifflin Company. ISBN 0-395-58389-6.