Anolis aquaticus

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Anolis aquaticus
Anolis aquaticus 60099739.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Dactyloidae
Genus: Anolis
Species:
A. aquaticus
Binomial name
Anolis aquaticus
Taylor, 1956
A well-camouflaged aquarit anole Anolis aquaticus.jpg
A well-camouflaged aquarit anole
An aquatic anole in Corcovado National Park, Costa Rica

Anolis aquaticus, commonly known as the water anole, is a semi-aquatic species of anole, a lizard in the family Dactyloidae, native to southwestern Costa Rica and far southwestern Panama. [2] The species demonstrates adaptations that allows it to spend periods of time underwater up to approximately a quarter of an hour, forming an air bubble which clings to its head and serves to recycle the animal's air supply while it spends time beneath the surface. [3] Although highly unusual, similar adaptions and behavior are found in other species of semi-aquatic anoles. [4] [5]

Contents

Taxonomy

The order of the water anole is Squamata, which refers to scaled reptiles. Squamata is the largest order of reptiles, including species of lizards, snakes, and amphisbaenians. Members of this order are found on every continent other than Antarctica, and they live in a variety of habitats, while showcasing various different traits. [6]

Iguania is a suborder that includes species of chameleons, iguanas, and New World lizards such as the water anole. Most species in the Iguania suborder are arboreal, meaning they travel by tree, but many other notable species are described as being terrestrial. They typically have tongues that are non-prehensile and fleshy, with the exception of chameleons. There are fossil records of members of this suborder dating back to the Early Jurassic period, with the earliest known member being the Bharatagama which lived in modern day India around 190 million years ago. [6]

The water anole is categorized in the group Dactyloidae, which is a family under the suborder Iguania. Dactyloidae refer to lizards that are in locations ranging from Paraguay to the southeastern regions of the United States, and are commonly referred to as anoles.

Anolis refers to a genus of anoles that are native to North and South America. There are currently more than 425 species that are known, and they are under the suborder Iguania and family Dactyloidae. Anolis used to be considered to be under the family Polychrotidae, but recently they have been categorized under the family Dactyloidae. [7]

Despite being under the same genus, different species under Anolis have exhibited many differences, mostly in the context of their habitat and location. They fill up different niches due to the isolation and separation of the species into significantly different habitats, which has led to morphological changes that better fit their habitats. Examples include a difference in limb length based on the diameter of the trees that different species walk on, with thinner trees leading to lizards with shorter limbs, and wider trees leading to lizards with longer limbs. The water anole, in contrast, is terrestrial, and spends most of its time on the ground or climbing rocks and large boulders. [7]

Physical description

The order Squamata are notable for their jaw structure, which provides them flexible jaws and a powerful biting force. Members of this order have developed a movable hinge in their skull called the quadratojugal hinge, and along with increased jaw muscle development, have given these organisms a strong biting force. Squamata are divided into many different suborders, and the water anole is part of the suborder Iguania. [6]

In most species of Dactyloidae, males have a flap of skin that extends from their necks, which is often brightly colored and used for display. Despite being very distantly related, they show many similarities to geckos, such as their anatomy and the ability to break off their tail. [8]

Body coloration

Being part of the group Dactyloidae, their bodies are most often a green or brown color, but like the water anole, many species are able to change colors. The water anole has the ability to change the color of the stripes that are throughout the length of their bodies. The colors display the level of stress that they are under. It has been determined through experimentation with the lizard species that brighter colored stripes signify that they are under more stress. When the lizard is exposed to a stressor, the stripes on the lizards' body transition from a brown color to a pale blue or green. [9]

These lizards also tend to use these brighter colored stripes when they are walking over surfaces that are dull colors, such as green and brown. This is called disruptive camouflage. With the use of contrasting colors and patterns, organisms are able to make the outlines of their body less visible to predators. [9]

The brighter body coloration is also used by individuals in the species to increase their mating success. By making their colors more noticeable and conspicuous, they are able to become more noticeable by potential mates. At the same time, however, the brighter colors also make them more susceptible to being attacked by predators. Water anoles with brighter body and dewlap coloration are attacked by predators at a higher rate than those with duller colors. Therefore, the trait of body coloration is one that is under the influence of two contradicting results: an increase in reproductive success and a decrease in survival rate. [10]

Behavior

Physiological

The water anole is unusual in that it is able to stay underwater for long periods of time – a behavior that is described as "scuba diving". Experiments have confirmed that this species has the ability to remain underwater for up to 16 minutes. Since these lizards have relatively slow running speeds compared to their predators, it has been hypothesized that these lizards have adapted this "scuba diving" to enable them to avoid predators. By submerging themselves underwater for prolonged periods of time, the water anole is able to remain invisible to its predator. These lizards often endure extreme hypoxia before returning to the surface if they perceive a predator and compromise their ability for future escape ability. [4] It has also been confirmed that many of the insects found in the water anoles' stomachs live primarily underwater. The water anoles use this "scuba diving" ability to hunt prey that live underwater and would otherwise be inaccessible to the lizards. Therefore, the anoles can escape predators and forage for food with this unique "scuba diving" behavior. [11] [12]

The reason that these lizards are able to remain submerged for long periods of time is their ability to create a bubble of air over heads while underwater. These anoles are semi-aquatic and when threatened or searching for prey they will jump from trees or rocks into water. When submerged, the lizards exhale and form an air bubble on the end of their snouts. Researchers have suggested that this species inhales and exhales the oxygen in the air bubble for a lengthy time period - a mechanism that ultimately permits their prolonged submersion. Researchers have also measured the oxygen saturation inside the air bubble over time and have found that it decreases with time underwater. This suggests the lizards are rebreathing through the air bubble. [12] In addition, it has been suggested that the lizard simultaneously uses the air bubble to remove carbon dioxide from its body. The inspiration of carbon dioxide shortens the duration of the dive and the air bubble can serve as a way to get rid of waste carbon dioxide. Carbon dioxide is highly soluble in water and because the partial pressure of carbon dioxide is much higher in the bubble than in the surrounding water, the carbon dioxide can easily be cleared from the bubble. [4] The formation of an air bubble in water anoles is likely facilitated by the highly hydrophobic character of their skin. [5] In 2024, the idea that these lizards use air bubbles for rebreathing was empirically tested by applying an emollient to their skin to prevent bubble formation. Lizards that could rebreathe normally were able to stay underwater an average 32% longer than those which could not. [13]

Social

The water anole exhibits the behavior of residing in different locations based on age and gender. These locations are determined based on their distance from the river, and their height above the river. Members of the species prefer to be located as close to the river as they can. Those of higher social or demographic class reside on higher perches, and live closer to the river. These perches are occupied by adult males, who tend to live on the highest perches and live closest to the river. Juvenile lizards and male lizards tend to live in exposed areas beside the river, while adult female lizards tend to choose areas that have cover. [14]

Reproduction

The reproductive season for this species is year round. On average, their clutch size is around one or two eggs per reproductive cycle. Female water anoles reach sexual maturity at an earlier age than their male counterparts, and also have a smaller snout-anus length than males do at their sexual maturity. Males have a larger growth rate than females, and they reach a greater body size than females when they are of the same age. Site selection has been determined to be carried out by the female, meaning that the male approaches the female in the mating process. Complete copulation takes from around 90 seconds to 105 seconds, and they do not exhibit any courtship behaviors after the copulation has concluded. The water anoles lay their eggs in cracks and openings in rocks and earth. The average incubation temperature is from 19° to 23 °C in natural conditions, and the average incubation time is from 75 to 82 days. [15]

Predators

There are three species that have been documented to be preying on the Anolis aquaticus: one species of crab and two species of bird. [16] When threatened, the Anolis aquaticus partakes in a combination of surface swimming and "scuba diving". These anti-predatory behaviors allow this lizard to migrate between the banks and boulders of its habitat into nearby streams. These behaviors may also allow the water anole to swim a short distance with upstream current or with the downstream current to a different location. In both scenarios, the water anole's ability to remain underwater for a prolonged period enables them to engage in both of these effective anti-predatory strategies. [17]

Population

There is some notable activity within the water anole species that can be seen by analyzing characteristics within the species' populations. The sex ratio in the population remains at around 1:1 between males and females. Females reach sexual maturity at around 4 to 6 months of age, and males reach sexual maturity at around 5 to 7 months of age. This means that on average, females reach sexual maturity earlier than males. Males in the species tend to keep one to three females in their territory, and these females do not allow other females from entering the territory. There is significant sexual dimorphism that can be seen by the size difference between males and females in the species, with males being larger than females. Although male adults grow to a larger size than female adults, their growth rates after they have reached adulthood is about the same. The growth rate of a juvenile male is therefore significantly greater than the growth rate of a juvenile female. [18]

The abundance of all members of a population, including males, females, and juveniles, fluctuates based on the season, with drier seasons yielding larger population sizes. The population sizes have been seen ranging from 86 individuals to 575 individuals, which would lead to different population densities based on the season. In populations of this species, there tends to be greater numbers of individuals that are mature and large in size compared to the relatively fewer individuals that are still considered juvenile. New members are introduced to a population and recruited at a rate of around 25% to 37% of the population size before recruitment. On average, more males are recruited than females, and males also tend to outlive and survive for a longer time than females. [16]

Evolution and adaptation

Diving lizards, such as the Anolis aquaticus, are believed to have evolved to be able to respire while staying underwater by holding air between their cuticles and the water that they are surrounded with. This is a development that was necessary for the lizards, that were initially terrestrial creatures restricted only to breathing directly through the air, to be able to dive underwater, which aids them in concealing themselves from predators. It is through this mechanisms that these semi-aquatic anoles are able to stay underwater for such long periods of time. These lizards have developed a method known as "rebreathing", in which they are able to breathe in and out using a nasal air bubble, which is made possible by a layer of air between the water and hydrophobic skin of the lizard. This hydrophobic skin, however, is a trait that can be seen among terrestrial anole species as well, that may benefit them in their ability to effectively dive. This suggests that a shift in function, or exaptation, may have occurred over the course of the anoles' evolution. [4]

Related Research Articles

<span class="mw-page-title-main">Dactyloidae</span> Family of reptiles

Dactyloidae are a family of lizards commonly known as anoles and native to warmer parts of the Americas, ranging from southeastern United States to Paraguay. Instead of treating it as a family, some authorities prefer to treat it as a subfamily, Dactyloinae, of the family Iguanidae. In the past they were included in the family Polychrotidae together with Polychrus, but the latter genus is not closely related to the true anoles.

<i>Anolis</i> Genus of lizards

Anolis is a genus of anoles, iguanian lizards in the family Dactyloidae, native to the Americas. With more than 425 species, it represents the world's most species-rich amniote tetrapod genus, although many of these have been proposed to be moved to other genera, in which case only about 45 Anolis species remain. Previously, it was classified under the family Polychrotidae that contained all the anoles, as well as Polychrus, but recent studies place it in the Dactyloidae.

<i>Anolis carolinensis</i> Species of reptile

Anolis carolinensis or green anole is a tree-dwelling species of anole lizard native to the southeastern United States and introduced to islands in the Pacific and Caribbean. A small to medium-sized lizard, the green anole is a trunk-crown ecomorph and can change its color to several shades from brown to green.

<span class="mw-page-title-main">Brown anole</span> Species of lizard

The brown anole, also known commonly as the Cuban brown anole, Bahaman anole, or De la Sagra's anole, is a species of lizard in the family Dactyloidae. The species is native to Cuba and the Bahamas. It has been widely introduced elsewhere, via the importation and exportation of plants where the anole would lay eggs in the soil of the pots, and is now found in Florida and other regions of the United States including southern Georgia, Texas, Louisiana, Tennessee, Mississippi, Alabama, Hawaii, North Carolina, and Southern California. It has also been introduced to other Caribbean islands, Mexico, and Taiwan.

<span class="mw-page-title-main">Knight anole</span> Species of lizard

The knight anole is the largest species of anole in the Dactyloidae family. Other common names include Cuban knight anole or Cuban giant anole, highlighting its native country, but it has also been introduced to Florida. In its native Cuba, this large anole is called chupacocote.

<span class="mw-page-title-main">Blue anole</span> Species of lizard

The blue anole is a species of lizard in the family Dactyloidae. A. gorgonae falls into the genus Dactyloa, which are all highly arboreal, but differ in size, coloration, and perch preferences. The blue anole specifically occupies higher perches. It is a small species which is "near threatened" and found only on the island of Gorgona, in the Colombian Pacific.

<i>Anolis cristatellus</i> Species of reptile

Anolis cristatellus is a small species of anole, belonging to the Dactyloidae family of reptiles. The species is native to Puerto Rico and the U.S. and British Virgin Islands, with introduced populations in locations around the Caribbean. The males of A. cristatellus are easily recognizable by the fin running down the top of the tail, which is known as a "caudal crest". The females also have this crest, but it is smaller than that of the males. The species is often quite common in many areas on Puerto Rico, where it can be seen during the day passing the time on the lower parts of tree trunks, or on fences and the walls of buildings in urban areas, sometimes venturing down onto the ground in order to lay eggs, have a snack, or do other cursorial activities. Like many anoles, this species displays the characteristic behaviour of doing push-ups as well as inflating a pizza-like flap of coloured skin on its throat, known as a dewlap, in order to show others how dominant it is, and thus attract mates or intimidate rivals.

<i>Anolis garmani</i> Species of lizard

Anolis garmani, also known commonly as the Jamaican giant anole, the Jamaican anole, and the Jamaica giant anole, is a species of lizard in the family Dactyloidae. The species is endemic to Jamaica, but has been introduced to Florida.

<i>Anolis cybotes</i> Species of reptile

Anolis cybotes, the large-headed anole, Tiburon stout anole, or Hispaniolan stout anole, is a species of anole endemic to the Tiburon Peninsula of Haiti. Reports from other places likely refer to other species that were formerly included in Anolis cybotes. This species gets its name from the male's strangely large head. It is often brownish in color with lighter stripes on the flanks.

<i>Anolis barbatus</i> Species of lizard

Anolis barbatus is a species of anole lizard from Western Cuba. Adults have a typical snout–vent length of about 18 cm (7 in), with tails that are slightly shorter than their bodies, and demonstrate little sexual dimorphism. It is one of six species called "false chameleons" that sometimes are recognized as their own genus Chamaeleolis or as the Cuban clade in Xiphosurus. These are all native to Cuba, fairly large for anoles, have robust heads, are dull gray-brown in color, slow-moving and have blunt teeth used for crushing snails, which is their main diet in the wild. Unusually among anoles, these all lack the ability to autotomize their tails. Together with the similar, but not closely related A. landestoyi of Hispaniola, they form a group known as the twig–giant ecomorph.

<i>Anolis occultus</i> Species of reptile

The Puerto Rican twig anole or dwarf anole is a species of small, arboreal anole endemic to Puerto Rico and primarily inhabiting the Cordillera Central from the Sierra de Cayey range in the Southeast to the central-western ranges of Maricao. A mostly grey to olive-brown bodied lizard, A. occultus is the smallest of the Puerto Rican anoles with a snout to vent length of 34–42 mm. In comparison to other twig anoles, A. occultus is extremely cryptic through its unique sleeping behaviors and mottled pattern. Sleeping behavior including site selection minimizes the probability of predator encounter along with A. occultus' extensive list of antipredator behaviors.

<i>Anolis richardii</i> Species of lizard

Anolis richardii, commonly known as the Grenada tree anole or Richard's anole, is a species of anole lizard in the family Dactyloidae. The species is found in the Caribbean.

<i>Anolis grahami</i> Species of lizard

Anolis grahami, commonly known as the Jamaican turquoise anole and Graham's anole, is a species of lizard in the family Dactyloidae. The species is native to the island of Jamaica, and has also been introduced to the territory of Bermuda. It is one of many different species of anole lizards found in Jamaica. There are two recognized subspecies.

<i>Anolis vermiculatus</i> Species of lizard

Anolis vermiculatus, the Vinales anole or Cuban stream anole, is a species of lizard in the family Dactyloidae, endemic to Cuba.

<i>Anolis eugenegrahami</i> Species of lizard

Anolis eugenegrahami, the Eugene's anole or the black stream anole, is a critically endangered species of lizard in the family Dactyloidae. This semi-aquatic species is endemic to northern Haiti.

<i>Anolis boettgeri</i> Species of lizard

Anolis boettgeri, also known commonly as Boettger's anole, is a species of lizard in the family Dactyloidae. The species is endemic to Peru.

Anolis danieli is a species of lizard in the family Dactyloidae. The species is endemic to Colombia.

<i>Anolis evermanni</i> Species of lizard

Anolis evermanni, also known commonly as the emerald anole, Evermann's anole, and the small green anole, is a species of lizard included within the family Dactyloidae. A. evermanni is native to Puerto Rico, where it is mainly found in wet forests. A. evermanni is a medium-sized lizard and bright emerald-green in color. A. evermanni is studied for its behavior as well as the evolution of the family Dactyloidae. The group of lizards which are member species of the family Dactyloidae are known as anoles. Anoles are found throughout the Americas and are related to iguanas.

<i>Anolis gundlachi</i> Species of lizard

Anolis gundlachi, also commonly known as the yellow-chinned anole, Gundlach's anole, and the yellow-beard anole, is an oviparous, sexually dimorphic species of lizard in the family Dactyloidae. The species is endemic to Puerto Rico and lives in mountainous forests at high elevations. The diet of A. gundlachi consists mostly of insects. This species is also known for signaling other lizards through a modulated head bob display, with varying bobbing amplitudes and patterns based on an individual's distance from other lizards.

<i>Anolis ibanezi</i> Species of lizard

Anolis ibanezi is a species of lizard in the family Dactyloidae. The species is native to Central America.

References

  1. ↑ Acosta Chaves, V., Batista, A., García Rodríguez, A., Saborío, G. & Vargas, J. (2020). "Anolis aquaticus ". The IUCN Red List of Threatened Species 2020: e.T203077A2759916. https://www.iucnredlist.org/species/203077/2759916. Downloaded on 29 March 2021.
  2. ↑ Rica), Victor Acosta Chaves (Universidad Nacional de Costa; Rica), Adrian García Rodríguez (Universidad de Costa; Osa), Guido Saborío (SINAC-Area de Conservación; Museum), Abel Batista (Senckenberg Natural History; Vargas, Joseph (2012-05-07). "IUCN Red List of Threatened Species: Anolis aquaticus". IUCN Red List of Threatened Species.
  3. ↑ "'Scuba-diving' lizard can stay underwater for 16 minutes". phys.org. Retrieved 2020-02-26.
  4. 1 2 3 4 Boccia, Christopher K.; Swierk, Lindsey; Ayala-Varela, Fernando P.; Boccia, James; Borges, Isabela L.; Estupiñán, Camilo Andres; Martin, Alexandra M.; Martínez-Grimaldo, Ramón E.; Ovalle, Sebastian; Senthivasan, Shreeram & Toyama, Ken S. (2021-07-12). "Repeated evolution of underwater rebreathing in diving Anolis lizards". Current Biology. 31 (13): 2947–2954.e4. Bibcode:2021CBio...31E2947B. doi: 10.1016/j.cub.2021.04.040 . PMID   33984265. S2CID   234495677.
  5. 1 2 Baeckens, Simon; Temmerman, Marie; Gorb, Stanislav N.; Neto, Chiara; Whiting, Martin J. & Van Damme, Raoul (2021-10-01). "Convergent evolution of skin surface microarchitecture and increased skin hydrophobicity in semi-aquatic anole lizards". Journal of Experimental Biology. 224 (19): jeb242939. doi:10.1242/jeb.242939. PMC   8541734 . PMID   34642763.
  6. 1 2 3 "Palaeos Vertebrates 240.000 Squamata Overview". 2008-11-06. Archived from the original on 2008-11-06. Retrieved 2021-10-08.
  7. 1 2 Poe; Nieto-Montes de Oca; Torres-Carvajal; Queiroz; Velasco; Truett; Gray; Ryan; Köhler; Ayala-Varela; Latella (2017). "A Phylogenetic, Biogeographic, and Taxonomic study of all Extant Species of Anolis (Squamata; Iguanidae)". Systematic Biology. 66 (5): 663–697. doi:10.1093/sysbio/syx029. PMID 28334227.
  8. ↑ Frost, Darrel R.; Etheridge, Richard Emmett (1989). A Phylogenetic analysis and taxonomy of iguanian lizards (Reptilia, Squamata). Museum of Comparative Zoology Harvard University. Lawrence, Kan. : University of Kansas. ISBN   978-0-89338-033-5.
  9. 1 2 Boyer, Jane F.F.; Swierk, Lindsey (2017-03-01). "Rapid body color brightening is associated with exposure to a stressor in an Anolis lizard". Canadian Journal of Zoology. 95 (3): 213–219. doi: 10.1139/cjz-2016-0200 . hdl:1807/75743. ISSN   0008-4301.
  10. ↑ Swierk, L.; Boyer, J. F. F.; Chang, J.; Petelo, M.; Drobniak, S. M. (2021-02-01). "Intrasexual variability of a conspicuous social signal influences attack rate of lizard models in an experimental test". Evolutionary Ecology. 35 (1): 131–146. Bibcode:2021EvEco..35..131S. doi:10.1007/s10682-020-10085-7. ISSN   1573-8477. S2CID   226324379.
  11. ↑ "'Scuba-diving' lizard can stay underwater for 16 minutes". phys.org. Retrieved 2021-10-08.
  12. 1 2 Gamillo, Elizabeth. "Diving Anole Lizards Use Bubbles to Breathe Underwater". Smithsonian Magazine. Retrieved 2021-10-19.
  13. ↑ Swierk, Lindsey (2024-09-18). "Novel rebreathing adaptation extends dive time in a semi-aquatic lizard". Biology Letters. 20 (20240371). doi:10.1098/rsbl.2024.0371. PMC  11407854. PMID   39288814.
  14. ↑ Eifer, Douglas (September 2010). "Use of Habitat by the Semiaquatic Lizard, Norops aquaticus". The Southwestern Naturalist. 55 (3): 466–469. doi:10.1894/PAS-19.1. S2CID   86497485.
  15. ↑ B, Cruz M. Márquez (2019-08-27). "Reproductive biology in the wild and in captivity of Anolis aquaticus (Sauria: Polychrotidae) in Costa Rica". Boletín Técnico, Serie Zoológica (in Spanish). 8 (4–5). ISSN   1390-3004.
  16. 1 2 Márquez, Cruz; R, Lady Márquez; P, Solanda Rea; R, Jefferson Márquez (2009). "Demografía de la población de Anolis aquaticus (Sauria Polychrotidae) de la quebrada La Palma, Puriscal, Costa Rica". Revista Ecuatoriana de Medicina y Ciencias Biológicas. 30 (1–2): 62–77. doi: 10.26807/remcb.v30i1-2.75 . ISSN   2477-9148.
  17. ↑ Swierk, Lindsey. "Anolis aquaticus (=Norops aquaticus)(Water Anole): Underwater breathing". Binghamton University.
  18. ↑ Márquez, Cruz; Mora, José Manuel; Bolaños, Federico; Rea, Solanda (January 2005). "Aspectos de la biología poblacional en el campo de Anolis aquaticus, Sauria: Polychridae en Costa Rica". Ecología Aplicada. 4 (1–2): 59–69. doi: 10.21704/rea.v4i1-2.299 . ISSN   1726-2216.
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