Seeing as today is the first day of Hawaii Invasive Species Awareness Week, I thought it was time to write a post on the beautiful but invasive (and illegal) veiled chameleon, Chamaeleo calyptratus. Most likely introduced to the islands through the pet trade, the male lizard can get as large as two feet. It's a habitat generalist, at home in dry low elevation areas as well as upland wet forests. And when it comes to dinner, these arboreal lizards aren't fussy either: plants, flowers, insects, small mammals and even birds will do. Putting these generalist qualities all together, you can imagine the destruction they could do to native bird and insect populations. Oh, and they can have babies - lots of babies. Unlike the Jackson's chameleon which gives birth live, these females lay eggs. After digging a hole in the ground she lays down thirty to ninety-five eggs per clutch, with up to three clutches per year. Half a year later, the baby chameleons hatch, and begin what can be an eight-year life span in the wild. It seems that the veiled chameleons are isolated to just a few spots in Maui, but the public is urged to contact officials if one is observed. Non-breeding females and juvies are mostly green with some white markings; larger adults can display vertical stripes, and a crayon-box of colors are possible depending on social and environmental factors. A fringe lines the belly from snout to tail. Like other chameleons, their eyes can move independently, and their crazy long tongues can be rapidly projected to ambush an unwary meal. Their prehensile tail helps them hang tight in the trees, and their flattened bodies can do a pretty good leaf imitation when they sway. But despite their intriguing features, best to recognize that these creatures pose a veiled threat to Hawaii's native treasures.
I wish I could end the tale of the Jackson's chameleon there, but the story is just getting started. As populations of these chameleons were getting established, there was little to no research on their ecological impact. In 2009, a study was published, entitled: A reptilian smoking gun: first record of invasive Jackson’s chameleon (Chamaeleo jacksonii) predation on native Hawaiian species. In this report, the authors documented predation of native tree snails by Jackon's chameleons. Further research is needed, but let it be yet another cautionary tale about how exotic species can disrupt the delicate balance of island ecosystems.
A Honu world; shimmering, shining, splendid. This is the glorious green sea turtle of Hawaii, Chelonia mydas. No matter how many times I see one, I am always happy to be in their graceful presence. Perhaps it is their ties to both land and water that make them so special to islanders around the world (they are found in nearly every ocean). To the delight of bathers and snorkelers, honu inhabit the shallow waters around the islands, grazing primarily on limu and sea grasses. As marine reptiles, they must come up occasionally for air, and will haul out on beaches for rest and for warming their cold-blooded bodies - an unusual behavior for sea turtles. Honu are the most common of the five species that visit Hawaiian waters, and the largest of the hard-shelled turtles, getting to lengths of three feet and weighing as much as three hundred plus pounds. The "green" in green sea turtle comes from the color of the fat layer between the shell and body.
Unlike their land-dwelling relatives, their feet have been modified into flippers, and their carapace streamlined into a teardrop shape. Good thing, because it's a long swim from their feeding grounds to the French Frigate Shoals, where they breed and nest on or near their natal beaches. Females make the trip every two to four years. After mating has occurred, she hauls up on the beach and flipper-digs a hole in the sand in which to lay her clutch of one hundred or more eggs. Once they have been tucked in all snug in their sandy bed, off she goes. She will repeat this process every couple of weeks, laying an average of five clutches during a season. About two months later, the hatchlings emerge and instinctively scramble to the water. It is a perilous journey, with any number of predators, and only a small percentage of the babies will survive to adulthood. They will forage in open waters for several years, during which time they are omnivores, unlike the adults which are primarily herbivores. Eventually, the juveniles will take up life in the shallows like their parents. With luck and our protection, these gentle friends may live as long as the humans they delight.
Of the eight gecko species here in Hawaii, the house gecko, Hemidactylus frenatus, is probably the one you are most familiar with. We've all seen their gravity defying jaunts across the ceiling or watched them chasing down cockroaches and moths. Yet we may not realize just how remarkable these lizards are. For starters, they can vocalize, chirping out the familiar tuk-tuk-tuk-tuk-tuk at night, and yet vocalizations are unusual for members of the Order Squamata, the group that includes all lizards and snakes. Secondly, they'll kill it in a staring contest as their eyelids are fixed; no blinking for this guy. Instead, they clean their eyes with their tongues. Their eyes are quite beautiful, with a vertical pupil that resembles a keyhole. They are also capable of caudal autotomy, the ability to lose part of their tail, as a defense mechanism. The severed appendage will continue to wriggle, further confusing the would-be predator.
And if that's not enough, consider their extraordinary toe pads. They are covered with small hairs called setae, which are mere micrometers in diameter and spatula-shaped at their ends. This allows for a great deal of surface area contact, and generates van der Waals forces, the same forces you learned about in Chemistry class that contribute to molecular bonding. This is what allows the gecko to do its spider-man thing. Scientists around the world are working on creating a synthetic version of the gecko toe pad. "Gecko tape," as it is often referred to, is still in its early phase of development, but could one day be used to hang televisions on walls, create fumble-free football gloves, or replace sutures in surgery. Others envision it on the boots of astronauts, enabling them to walk on the space craft unencumbered by harnesses. That little friend hanging around your porch light could one day have us literally climbing the walls.
Update: Aug 26th, 2014: Seems as though there may be a color morph of the brown anole. While unusual, this red variation of Anolis sagrei has been documented. When an interestingly colored lizard showed up in the backyard of reader on Oahu, she and her husband took the time to send me a photo. Please let me know if you've seen similar lizards.
welcomes you to visit with the all the wonderful flora and fauna that we share this lovely aina with.