Ctenophorus Nuchalis Research Articles

Morphological and molecular characterization of Isospora amphiboluri (Apicomplexa: Eimeriidae), a coccidian parasite, in a central netted dragon (Ctenophorus nuchalis) (De Vis, 1884) in Australia.

An Isospora species, Isospora amphiboluri, originally described by Canon in 1967 and later by McAllister et al. (1995), was isolated from a central netted dragon (Ctenophorus nuchalis) housed at a wildlife rehabilitation centre in Perth, Western Australia. Sporulated oocysts of Isospora amphiboluri (n=30) are spherical, 24.2 (26.5-23.0) μm in length and 23.9 (22.4-25.9) μm in width, with a shape index of 1.01. The bilayered oocyst wall is smooth and light-yellow in color. Polar granule, oocyst residuum and micropyle are absent. The sporocysts are lemon-shaped, 15.7 (15.2-18.0)×10.2 (8.9-11.2) μm, with a shape index (length/width) of 1.53. Stieda and substieda bodies are present, the Stieda body being small and hemidome-shaped and the substieda half-moon-shaped. Each sporocyst contains four vermiform sporozoites arranged head to tail. The sporozoites are 11.7 (9.9-16.2)×3.0 (2.4-3.5) μm, with a shape index (length/width) of 3.87. A sporocyst residuum is present. Sporozoites contain a central nucleus with a finely distributed granular residuum. Comparison of oocyst measurements and their features with other valid Isospora species from hosts in the Agamid family confirmed that this Isospora species is Isospora amphiboluri. Molecular characterization of I. amphiboluri at the 18S rRNA and MTCOI loci showed the highest similarity with I. amphiboluri from the central bearded dragon, 99.8% and 99.7% respectively. This is the first report of I. amphiboluri from a central netted dragon in Australia.

Zebrin II Is Expressed in Sagittal Stripes in the Cerebellum of Dragon Lizards (Ctenophorus sp.)

Aldolase C, also known as zebrin II (ZII), is a glycolytic enzyme that is expressed in cerebellar Purkinje cells of the vertebrate cerebellum. In both mammals and birds, ZII is expressed heterogeneously, such that there are sagittal stripes of Purkinje cells with high ZII expression (ZII+) alternating with stripes of Purkinje cells with little or no expression (ZII-). In contrast, in snakes and turtles, ZII is not expressed heterogeneously; rather all Purkinje cells are ZII+. Here, we examined the expression of ZII in the cerebellum of lizards to elucidate the evolutionary origins of ZII stripes in Sauropsida. We focused on the central netted dragon (Ctenophorus nuchalis) but also examined cerebellar ZII expression in 5 other dragon species (Ctenophorus spp.). In contrast to what has been observed in snakes and turtles, we found that in these lizards, ZII is heterogeneously expressed. In the posterior part of the cerebellum, on each side of the midline, there were 3 sagittal stripes consisting of Purkinje cells with high ZII expression (ZII+) alternating with 2 sagittal stripes with weaker ZII expression (ZIIw). More anteriorly, most of the Purkinje cells were ZII+, except laterally, where the Purkinje cells did not express ZII (ZII-). Finally, all Purkinje cells in the auricle (flocculus) were ZII-. Overall, the parasagittal heterogeneous expression of ZII in the cerebellum of lizards is similar to that in mammals and birds, and contrasts with the homogenous ZII+ expression seen in snakes and turtles. We suggest that a sagittal heterogeneous expression of ZII represents the ancestral condition in stem reptiles which was lost in snakes and turtles.

Molecular detection of two adenoviruses associated with disease in Australian lizards

We give the first published description of the pathology and molecular findings associated with adenovirus infection in lizards in Australia. A central netted dragon (Ctenophorus nuchalis) exhibited severe necrotising hepatitis with abundant intranuclear inclusion bodies within hepatocytes and rarely within intestinal epithelial cells. Polymerase chain reaction (PCR) using pooled tissues yielded an amplicon that shared strong nucleotide identity with an agamid adenovirus (EU914203). PCR on the liver of a bearded dragon (Pogona minor minor) with illthrift, coccidiosis, nematodiasis and hepatic lipidosis yielded an amplicon with strong nucleotide identity to a helodermatid adenovirus (EU914207).

Lizard responses to wildfire in arid interior Australia: Long‐term experimental data and commonalities with other studies

AbstractLife in terrestrial Australian ecosystems has evolved over the past 10 million years to thrive in habitats kept in a dynamic state through fire succession cycles. Previous studies support the notion that wildfires promote species diversity in plant and animal communities by creating a heterogeneous mix of habitats, each habitat more suitable for particular subsets of species. We document population and community responses to fire in a species‐rich lizard assemblage in the Great Victoria Desert of Western Australia. Lizards were censused by pit trapping at a long‐unburned flat spinifex site in the Great Victoria Desert in Austral springs of 1992 and 1995. A controlled burn was undertaken in mid‐October of 1995, and lizards were censused thereafter in late 1995 and early 1996, and then again in the Austral springs of 1998, 2003 and 2008. Forty‐six species of lizards (2872 individuals) were collected and their stomach contents analysed over the course of a 16‐year fire succession cycle at this single study site. Most strikingly, relative abundances of two species of agamids varied inversely, responding oppositely to habitat clearing effects of fire. The military dragon Ctenophorus isolepis reached higher abundances when vegetation was dense, and decreased in abundance in open vegetation following fire. The netted dragon Ctenophorus nuchalis was rare when vegetation coverage was high but increased rapidly after fire. Abundances of five species of Ctenotus skinks, C. ariadnae, C. calurus, C. hanloni, C. pantherinus and C. piankai, tracked those of C. isolepis. Abundance of a termite‐specialized nocturnal gecko, Rhynchoedura ornata, increased in abundance following fire. Lizard diets changed during the course of the fire succession cycle, returning to near pre‐burn conditions after 16 years. In addition to short‐term fire succession cycles that contribute to structuring local communities, changes in long‐term rainfall also impact desert food webs and regional biotas.

Seven lizard species and a blind snake: activity, body condition and growth of desert herpetofauna in relation to rainfall

In the Australian arid zone, primary productivity is highly variable in response to irregular and unpredictable rainfall and this has major flow-on effects for desert fauna. We measured temporal patterns of activity and body condition of eight reptile species, and growth for the three most abundant species, in a dry and a wet year. Activity and body condition of the diurnal lizards Ctenophorus nuchalis and Amphibolurus gilberti (Agamidae) and Ctenotus leonhardii and Ctenotus schomburgkii (Scincidae) varied predictably. In the dry year the onset of warm-season activity was delayed and body condition was low, whereas high levels of activity and body condition were observed in the wet year. Growth rates of C. schomburgkii, C. leonhardii, and C. nuchalis did not differ between the two years. Body condition of the nocturnal lizards Diplodactylus conspicillatus and Rhynchoedura ornata (Gekkonidae) and Lerista labialis (Scincidae) did not differ between years but the nocturnal blind snake Ramphotyphlops centralis (Typhlopidae) had higher condition in the wet year. Nocturnal species were active only in warmer months and this apparently limited their ability to respond to favourable conditions in the wet year. Temporal patterns of activity may be important determinants of how effectively lizards can make use of available resources after rain.

Experimental trial of Australian arid zone reptiles as early warning indicators of overgrazing by cattle

The value of reptiles as bioindicators of the initial effects of heavy cattle grazing in a South Australian chenopod shrubland was assessed in an experimental trial. Reptiles were sampled in three different subhabitats within two replicate treatment paddocks and a control region. A total of 30 sites was sampled in two sessions before grazing and four sessions after the commencement of intensive pulses of grazing. Capture rates of most common reptile species, fecundity of abundant gecko species and reptile species composition within different subhabitats were largely resilient to the initial effects of overgrazing. However, agamids in general, and particularly Ctenophorus nuchalis, increased at grazed sites relative to controls following grazing. Most changes observed in the reptile assemblages were predictable based upon species response to alteration in vegetation cover. Because vegetation cover can be rapidly and efficiently monitored, the use of reptiles as early warning indicators of unsustainable pastoralism in the study region was not supported.

Selection of habitat components by two species of agamid lizards in sandridge desert, central Australia

Abstract We studied the use and selection of habitat components by two species of agamid (dragon) lizards in the Simpson Desert, Queensland, Australia. Both the military dragon (Ctenophorus isolepis) and central netted dragon (Ctenophorus nuchalis) were captured in pitfall traps surrounded by areas of open sand, but the mean coverage of spinifex (Triodia basedowii) was greater (35%) around traps capturing C. isolepis than around those capturing its congener (approx. 8%). Direct observations of free‐ranging lizards confirmed that C. isolepis spent most time in, or within 30 cm of, spinifex hummocks, whereas C. nuchalis primarily perched in dead wood. Both species spent most (≥75%) of the time they were observed at rest, with little time spent feeding or moving. Ctenophorus isolepis spent 67% of its time in shade and was active in temperatures between 37.5°C and 43.3°C, whereas C. nuchalis spent 81% of its time in open sun and was active between 35.9°C and 48.1°C. Transect surveys at observation sites showed that open sand was the dominant habitat component available to both species. However, sand was under‐used compared with its availability. Ctenophorus isolepis instead showed strong selection for spinifex cover and C. nuchalis for dead wood; shrub cover was little used. We discuss several mechanisms that may drive the observed pattern of habitat selection, but cannot specify which is the most important. However, the results indicate clear partitioning of habitat between the two species, and suggest that this segregation may facilitate coexistence at local and regional scales.

The effects of grazing and fire on vegetation and the vertebrate assemblage in a tropical savanna woodland in north-eastern Australia

We studied the response of vegetation and vertebrate assemblages to fire and grazing, and their interacting effects, in Eucalyptus woodland in north-eastern Australia. In this vegetation type, many pastures remain free of cattle grazing due to the occurrence of a native shrub poisonous to livestock. Vegetation (floristic data and 22 habitat variables) and vertebrate fauna (birds, mammals, reptiles) were sampled in 29 standardized 50 × 50-m quadrats in the 2001 wet season, representing four treatments: sites burnt recently (within 2 y) and grazed by cattle (4–8 ha per livestock unit); sites unburnt (last burnt >2 y ago) and grazed; sites burnt recently and ungrazed; and unburnt and ungrazed sites. Fire and grazing had a significant influence on vegetation: both grazing and fire reduced ground cover (fire in grazed sites 51–23%, fire in ungrazed sites 68–39%) and increased the cover of forbs (8% in burnt and grazed sites, 3% if ungrazed) and tussock grasses (20% in grazed and unburnt sites and 5% when ungrazed). Grazing caused a shift in floristic composition from the perennial hummock grass Trioda pungens to tussock grasses (e.g. Aristida spp., Enneapogon spp.), forbs (e.g. Phyllanthus spp.) and shrubs (e.g. Acacia spp.). Of the vertebrate groups, birds responded more to fire effects (9 species), reptiles to grazing effects (6 species) and mammals to the interaction (2 species). Species reacted to increases in bare ground (e.g. crested pigeon Ocyphaps lophotes, hooded robin Melanodryas cucullatus, Ctenophorus nuchalis) and to the dominant ground cover (e.g. Ctenotus pantherinus) or change in vegetation architecture (e.g. singing honeyeater Lichenostomus virescens, variegated fairy-wren Malurus lamberti). The clearest example of an interacting effect was the cycle of complementary dominance between the rodents Pseudomys delicatulus and P. desertor, the latter's post-fire recovery becoming more muted in sites where cattle grazed (modelled time for population recovery twice as long as in ungrazed sites).

Kidney function and the role of arginine vasotocin in three agamid lizards from habitats of differing aridity in Western Australia

Western Australian agamid lizards are diverse and inhabit mesic to very arid areas of the state. Although reptilian kidneys are unable to elaborate hyperosmotic urine, we hypothesised that the renal system of lizards inhabiting arid areas would display an enhanced ability to conserve water under the control of the antidiuretic peptide hormone, arginine vasotocin (AVT). To examine this, the renal physiological and endocrine responses to osmotic challenge in three closely-related Australian agamid lizards inhabiting arid, semi-arid, and mesic environments were studied. The species studied were Pogona minor (mesic), Ctenophorus salinarum (semi-arid), and Ctenophorus nuchalis (arid). Circulating AVT was assayed and renal variables such as glomerular filtration rate (GFR), urine flow rate ( V), and fractional reabsorption of filtrate ( FR H 2 O ) were measured in response to hypernatraemia, water load, and dehydration. Hypernatraemia and dehydration induced antidiuresis in all three species through similar mechanisms involving both glomerular and tubular responses. However, in salt-loaded P. minor the response was largely glomerular in nature, as FR H 2 O did not increase relative to the hydrated condition. The magnitude of the antidiuretic response was also greater in P. minor, indicating a greater sensitivity to osmotic challenge. Plasma concentrations of AVT were significantly correlated with FR H 2 O in P. minor ( r 2 = 0.38, P = 0.025), but with GFR in C. nuchalis ( r 2 = 0.16, P = 0.041). We found that the control and mechanisms of renal function among these lizards were largely similar, and there was little support for the hypothesis that arid lizards possess physiological adaptations not present in closely-related mesic lizards. Yet, differences remain in their response to hypernatraemia which may reflect the aridity of their different environments, or their varying habits.

Population dynamics of two species of dragon lizards in arid Australia: the effects of rainfall.

The population dynamics of two species of agamid (dragon) lizards were studied in the Simpson Desert, central Australia, over a period of 7 years, and modelled in relation to rainfall. Both species have annual life cycles, with adults predominating during the breeding season in spring and summer and juveniles predominating in other seasons. Within years, juvenile abundance in both species in autumn and winter was related most strongly to rainfall in the preceding summer and autumn. This pattern suggests that rainfall enhances survival, growth and possibly clutch size and hatching success. Between years, however, rainfall drove successional change in the dominant plant species in the study area, spinifex Triodia basedowii, causing in turn a shift in the relative abundance of the two species. Thus, the central netted dragon Ctenophorus nuchalis was most numerous in 1990 when vegetation cover was <10%, but declined dramatically in abundance after heavy rainfall at the end of that year. In contrast, the military dragon C. isolepis achieved greatest abundance following heavy rains in the summers of 1990 and 1994, when spinifex cover increased to >20%, and remained numerically dominant for much of the study. We suggest that drought-wet cycles periodically reverse the dominance of the two species of Ctenophorus, and perhaps of other lizard species also, thus enhancing local species diversity over time. Further long-term studies are needed to document the population dynamics of other species, and to identify the factors that influence them.

Ecological and toxicological effects of exposure to an acidic, radioactive tailings storage

The persistence of an island of remnant vegetation within a tailings retention system provided an opportunity to conduct a pilot study to develop hypothesis concerning the impacts of acid spray and radiation on arid zone flora and fauna. Ecological changes were investigated by comparing species abundance and condition on both the study island and remote control areas. Hopbush (Dodonaea viscosa), geckos and a common ant species, Iridomyrmex rufoniger sp. B were abundant in control regions but absent from the study region, whereas densities of colonising plant species, Helea beetles and scorpions were unusually high at the impacted site. These disparities are probably attributable to acid spray at the impacted site and hence are potentially useful bioindicators of these impacts. Dragon and skink populations were apparently unaffected by the polluted ecosystem, although Ctenophorus nuchalis proved to be a significant bioaccumulator of radionuclides. Bioaccumulation of the radionuclides, 238U, 230Th, 210Pb and particularly 210Po were significantly greater than that reported elsewhere in the literature. Further radionuclide monitoring of herbivorous dragon species, possibly concentrating upon 210Po levels, was the suggested outcome of this pilot study.

Subhabitat variability: A key to the high reptile diversity in chenopod shrublands

Abstract The herpetofauna of one hectare of chenopod shrubland near Roxby Downs in arid South Australia was studied from January 1991 until June 1993. The subhabitat preferences of 27 reptile species and one frog species were investigated by analysing capture rates, from more than 1800 captures in 401 pit traps. Although the site was characterized by relatively uniform cover of the dominant plant species Atriplex vesicaria, significant variation occurred in rock cover, and in edaphic and floristic features. Ctenophorus fordi, Ctenotus brooksi and Lerista labialis were strongly associated with sandy regions while Tympanocryptis intima, Diplodactylus tessellatus and Ctenotus strauchii were largely restricted to rocky subhabitats. Ctenotus leonhardii was strongly associated with a high density of Maireana species. Subhabitat preference of some of these species could be explained by the defence strategies they employed. Several species such as Ctenophorus nuchalis, Pogona vitticeps, Tympanocryptis lineata, Diplodactylus stenodactylus, Rhynchoedura ornata, Menetia greyii and Neobatrachus centralis were subhabitat generalists within the study site. The biological appropriateness of using a smaller number of subhabitat groupings, rather than the square root of the number of study sites, was confirmed in this study. Five subhabitat groups yielded meaningful preference data for more species than did 10 or 20 groups, and did not lose resolution achieved through higher level clustering.

Energetics, osmoregulation, and food consumption by free-living desert lizards, Ctenophorus (= Amphibolurus) nuchalis

Abstract The ecophysiology of the agamid lizard Ctenophorus nuchalis was studied near Shark Bay, Western Australia, during three seasons, over four years, in order to evaluate seasonal and year-to-year variation in energy and material balance, and to compare this agamid with similar-sized iguanid lizards. We measured water influx and efflux rates and field metabolic rates with doubly-labelled water, sodium fluxes with radiosodium, and osmotic status (plasma osmotic and ionic concentrations) in free-ranging adults of both sexes, as well as juveniles. Feeding rates were calculated from diet composition information in conjunction with rates of water and sodium intake, and body condition indices were also determined. There were marked seasonal and year-to-year differences in body condition, and in rates of body mass gain or loss, and these correlated with drought periods. Rates of resource use were highest in spring, and declined through summer and autumn, and rates were lowest during 1983, a year having unusually low winter rainfall. Hatchlings, which emerged in autumn, were able to find and capture food resources, even though adults were eating little during that season. The annual pattern of energy, water and salt balance in this agamid lizard is quite similar to that of an equivalent-sized iguanid lizard.

The role of surfactant in the static lung mechanics of the lizard Ctenophorus nuchalis

We previously showed that the lung of the central Australian lizard, Ctenophorus nuchalis, contains a large amount of surfactant, the composition of which varies with body temperature. We now show that the specific compliance of the lungs of these lizards remains constant regardless of whether they were maintained at 10, 18, 27, 37 or 43°C for 4 hours. In contrast, the opening pressure was constant up to 27°C, but decreased at 37 and 43°C. When we lavaged the lungs in situ to remove the majority of surfactant, specific compliance decreased while opening pressure increased. The lungs of C. nuchalis are essentially two bubbles, with the left one larger at low and intermediate volumes. After collapsing both lungs, the larger left lung always inflated first. However, following lavage the smaller right lung inflated first. As the larger lung, when collapsed, would have a much greater area of epithelial contact, this result is consistent with surfactant acting as an ‘antiglue’. During deflation the smaller lung collapsed first, consistent with the law of Laplace. Compliance did not change in the saline-filled lung suggesting that the gas-liquid interface does not play a major role. We conclude that in the lungs of these lizards, surfactant is acting as an antiglue. This might be important during periods of apnea at low body temperatures, when residual volume is small and epithelial surfaces may come into contact.

Lung Ultrastructure and the Surfactant-Like System of the Central Netted Dragon, Ctenophorus nuchalis

We have examined the ultrastructure of the unicameral lung of the central netted dragon, Ctenophorus nuchalis, using light, scanning electron, and transmission electron microscopy. The inside of the outer wall of the saccular lung were oriented perpendicularly to the wall. On the luminal side, the openings of the faveoli were connected by a network of smooth muscle bundles (trabeculae). Whereas the faveoli are 10 to 100 times larger than alveoli from similarly sized mammals, we previously found that the amount of surfactant-like material which can be lavaged from these lungs is about 70 times greater per surface area of lung than that from a similar sized mammal. The lungs of C. nuchalis contained very large numbers of alveolar type II cells, often located in groups, and sometimes apparently stratified. Each cell contained many lamellar bodies in its cytoplasm. A number of different forms of extracellular surfactant, including the distinctive, cross-hatched appearing, tubular myelin, were apparent in the airspaces. During deflation, the walls of the faveoli fold in a concertina fashion between the outer wall of the lung and the apparently more rigid primary trabecular network. Large amounts of extracellular surfactant-like material could be seen in the corners which were so formed. This location is consistent with this material acting as an anti-glue in the lizard lungs, facilitating the unfolding of the epithelial linings during inflation. The large number of cilia and their position is consistent with a cleaning function in which surfactant may also be involved.

The Topographic Organization of the Retinal Ganglion Cell Layer of the Lizard Ctenophorus nuchalis.

The numbers of neurons of the ganglion cell layer (GCL) and their distribution in the retina of an Australian lizard Ctenophorus nuchalis were investigated. Retinal wholemounts and sections were prepared for light microscopic and optic nerves for electron microscopic study. Counts of cell numbers in the GCL from wholemounts varied from 200,000 to 380,000. Neurons in the GCL were non-uniformly distributed, forming a high cell density streak along the naso-temporal axis of the retina. Neurons of the GCL formed 2 to 9 layers in the visual streak and a single layer in the rest of the retina. The number of neurons of the GCL in this area was estimated at about 2,100,000. Although the visual streak represented only 16% of the total retinal surface area, it contained about 90% of all neurons of the GCL. Optic axon counts yielded 147,000 myelinated and 2,643,000 unmyelinated fibres. The estimated optic fibre number of 2,790,000 was 18.2% less than the total number of neurons counted from sections in the GCL of the same eye. The unexpected high number of neurons in the area of the visual streak indicates that cell numbers obtained only from wholemount preparations may vastly underestimate the total neuron numbers in the GCL of the lizard retina.

Temperature effects on ventilation and metabolism in the lizard, Ctenophorus nuchalis

The effect of temperature upon ventilation and metabolism was measured on a breath by breath basis in the lizard Ctenophorus nuchalis. This species displayed a typical reptilian breathing pattern; groups of breaths separated by periods of breath holding. The lengths of the non-ventilatory periods (NVP) decreased as temperature increased. As a result, overall breathing frequency (f) displayed a thermal dependence. Outside the preferred temperature range (27–37°C) f was also affected by changes in the frequency of breathing that occurred during periods of ventilation (f′). On the other hand, tidal volume (V t) was maintained constant at all temperatures except 42°C (‘panting’ threshold). Thus, due to the thermal dependency off, ventilation (V̇ e) displayed a significant increase between 18 and 37°C. Metabolism (V̇ O 2 and V̇ CO 2 ) also increased within this temperature range. However, as a result of a lower Q 10 for ventilation, ventilatory requirement (V̇ e/V̇ O 2 and V̇ e/V̇ CO 2 ) decreased. In addition, lung volume (LV) increased with temperature. Examination of the alveolar ventilation-P CO 2 relationship revealed that as a result of the increase in LV the level of intrapulmonary CO 2 at the end of an NVP was maintained irrespective of temperature. This implies a temperature-independent chemical threshold for the onset of breathing. It is postulated that with temperature the observed increase in LV could offset the increase in metabolism by slowing the rise of intrapulmonary CO 2 levels. This would delay the onset of breathing which in turn would lower V̇ e/V̇ CO 2 (and V̇ e/V̇ 2 ) by preventing an effectual hyperventilation. This supports the notion, at least in C. nuchalis, that relative alkalinity is maintained.

Body Temperature Alters the Lipid Composition of Pulmonary Surfactant in the LizardCtenophorus nuchalis

In any 24-h period the body temperature (Tb) of the central Australian agamid lizard, Ctenophorus nuchalis, may vary from 13 to 45 degrees C; the mean preferred Tb is 37 degrees C. We have analyzed surfactant-type lipids in lizards that underwent rapid changes in Tb from 37 degrees C to 14, 19, 27, or 44 degrees C. Lipids were extracted from lung lavage and lamellar body fractions, and phospholipids and cholesterol components were measured. There was no change in either the total amount or relative proportions of the different classes of phospholipids, but cooling increased the cholesterol content of lavage. An increase in the cholesterol: phospholipid ratio was evident within 2 h of cooling to 19 degrees C and was maintained for at least 48 h. The ratio increased from 8% at 37 degrees C, to 15% after 4 h at 19 degrees C, and 18% after 4 h at 14 degrees C. Possibly the increase in cholesterol promotes fluidity and absorption of surfactant within the alveoli of lizards with low Tb. Cold lizards collapse their lungs during prolonged periods of apnea and the surfactant may prevent the epithelial walls from adhering.

A comparison of the surfactant associated lipids derived from reptilian and mammalian lungs

The lungs of the central netted dragon Ctenophorus nuchalis are bag-like, with most of the gas exchange region located in the anterior third. Although the faveoli are much larger than the mammalian alveoli, the lizard at 37°C has approximately 70 times more surfactant phospolipid per unit area of respiratory surface than does a similar sized mammal. However, when expressed as per wet lung weight, lizards and rats possessed similar amounts of phospholipids. Dipalmitoylphosphatidylcholine was the principal phospholipid in both species. However, major differences existed in the phospholipid, neutral lipid and fatty acid profiles. Whereas the lizard contained neither phosphatidylglycerol nor phosphatidyl-ethanolamine it had more cholesterol, esterified cholesterol, acylglycerides and unsaturated fatty acids. Although the ratio of saturated: unsaturated fatty acids was similar in rats and lizards, palmitic acid predominated in the former. The composition of lizard surfactant suggests that it would adsorb rapidly at reduced body temperature.