Crocodylus Porosus Research Articles

Quantification of plasma corticosterone in juvenile farmed saltwater crocodiles (Crocodylus porosus) using current Australian Code of Practice guidelines

Saltwater crocodiles (Crocodylus porosus) across three size categories (hatchlings, grower and harvest-size) were repeatedly blood sampled on two farms in the Northern Territory, Australia to determine reference plasma corticosterone (CORT; crocodilian stress hormone) levels. The mean CORT values for hatchlings (<1 year old), growers (1–3 years) and harvest-size individuals (2 + years) were 1.65 ± 0.15 ng/ml, 2.73 ± 0.21 ng/ml and 2.19 ± 0.16 ng/ml, respectively. No inter-farm differences within the hatchling or harvest-size crocodiles were detected, but growers on Farm 2 had significantly lower plasma CORT than those on Farm 1. However, the grower growth rate coefficients were the same across both farms so the repeated blood sampling design most likely contributed to the difference in CORT values rather than any management procedures. Plasma corticosterone levels significantly increased with time of day. Substantial variation in plasma CORT was observed at each sampling which is not unprecedented in the literature but requires further elucidation. Irrespective, as CORT values were generally low, our results suggest that the farming environment and husbandry practices, as implemented under the Australian industry Code of Practice, are effective as baseline animal welfare measures although they should be viewed as a foundation for further welfare research and not considered static.

Precious reptiles: Social engagement and placemaking with saltwater crocodiles

In this paper I take up the call to expand the boundaries of social and physical landscapes in order to recognise the creative agencies of human and non‐human actors. In doing so, I wish to draw attention to the ways in which relations between both individuals and collectives combine to shape multi‐dimensional sociality in particular places. The place in question is a crocodile farm in tropical Australia. It is a curious place in that it was fostered by modes of objectification which serve to commoditise and conserve crocodiles at a species level with little attention to individuality. However, the particularity of crocodiles at the farming level compels their human handlers to make concessions to their demands. Crocodiles, by their refusals, attachments and individualities, elicit attention to their needs, which translates into practices and structures that are often at odds with profitability. In this way it is as much social processes as it is practicalities of producing skins which affect the farmed landscape and the beings it produces, creating a nexus of multispecies place‐making where individuals matter.

Population status and spatial distribution of saltwater crocodile, Crocodylus porosus in the Sundarbans of Bangladesh

The Saltwater Crocodile, Crocodylus porosus is endangered in Bangladesh, and currently surviving in rivers and channels of the Sundarbans mangrove forest of the country. Very little information is available on this apex predator in the Sundarbans aquatic ecosystem, therefore a survey was carried out to assess population status and their spatial distribution. By surveying approximately 351 km of rivers of the Bangladesh Sundarbans during daytime between 2014 and 2015, a total of 42 individual crocodiles were recorded, with an overall encounter rate of 0.12 crocodiles (SE = 0.02, 95% CI = 0.08 - 0.18) per km of rivers. Based on this estimate, it is inferred that a population of approximately 140 crocodiles (95% CI = 90 - 190) could occur in the Bangladesh Sundarbans. The generalised linear model revealed statistically insignificant negative relationship of relative crocodile abundance with the salinity level (β = –0.067, SE = 0.057, p = 0.242) and protection status (β = –0.208, SE = 0.855, p = 0.808), and statistically insignificant positive relationship with the distance to human habitations (β = 0.004, SE = 0.039, p = 0.914). Disturbance by resource collectors, cargo vessels, and water pollution are the major threats to crocodile populations of the Sundarbans. The results of this study will be useful in future population monitoring to guide conservation management of saltwater crocodile in this important habitat.

Correction: Estuarine crocodiles in a tropical coastal floodplain obtain nutrition from terrestrial prey

[This corrects the article DOI: 10.1371/journal.pone.0197159.].

Hepatic and Renal Lesions in Free Ranging Black Caimans (Melanosuchus niger) in the Brazilian Amazon for Human Consumption

Background: The black caiman (Melanosuchus niger), belongs to the order Crocodylia, family Alligatoridae. More than a hundred species of helminths, mainly trematodes and nematodes, parasitize crocodilians around the world and a considerable number of species of ascaris have been described in crocodilians. There are few descriptions of hepatic and renal diseases affecting M. niger, and no articles related to the histopathological aspects of this species were found. The aim of this study was to evaluate gross and microscopically the liver and kidneys of 100 specimens of Melanosuchus niger slaughtered in Reserva de Desenvolvimento Sustentável Mamirauá, from natural populations.Materials, Methods &amp; Results: The capture of the alligators was performed during the night, by members of the community itself in the channels and lagoons of the Reserve's lowland ecosystem. For the capture procedures, ties and harpoons were used and the animals were identified through the red glow of the eyes using the spot light lanterns. After being conducted to the slaughter area, the animals were submitted to the previous biometry to select which animals were appropriated for slaughter, they should measure between 2.10 m and 2.80 m. A total of 88 livers and 95 kidneys of M. niger of natural populations were analysed gross and microscopically, independently of gross lesions. The fragments collected for histopathological examination were approximately 0.5 cm thick and they were packed in appropriated identified containers with formalin 10% solution. The collection procedures were accompanied by field records for data recording. After fixation of the collected material, it were processes by habitual techniques for paraffin inclusion and hematoxylin-eosin staining. Grossly, none of the livers examined presented alterations and two kidneys presented parasitism. The hepatic microscopic analysis indicates in 3/88 cases, multiple foci of necrosis. In 7/88 cases, it was observed in the hepatic parenchyma, granulomas, mainly with epithelioid cells. In the histopathological examination of the kidney, the only alteration observe in 8/95 cases was the presence of granulomas.Discussion: The occurrence of Sebekia oxycephala nymphs, a pentastomid, in the liver of Alligator mississippiensis was reported in other researches. The parasite Sebekia mississippiensis was observed in liver and lungs of A. mississippiensis. similar alterations were also noticed in this research. The coccidiosis related to hepatic manifestations in crocodilians is related to the parasite that may belong to the genus Goussia. In the liver, under the oocysts form leads to a diffuse hydropic degeneration of hepatocytes. In this study it was also observed the hydronic degeneration, however, associated to the necrosis areas that had in the periphery epithelioid cells infiltrated, without parasitic participation. Two renal trematodes are known in crocodilians, Deurithrema gingae and Renivermis crocodyli both in Crocodylus porosus. Also it was found in the renal parenchyma few encapsulated and well delimited parasites by a severe tissue reaction. Based on the gross and microscopic found, it is concluded that liver and kidney, although multiple organ functions, were not prone to infections, with granulomas being the main manifestation, and the etiopathogenesis of the areas of hepatic necrosis could not be defined.

Estuarine crocodiles in a tropical coastal floodplain obtain nutrition from terrestrial prey.

The estuarine crocodile (Crocodylus porosus) is one of the largest and most widespread crocodilians in the world. Although considered an apex species, the role of the estuarine crocodile in aquatic foodwebs is poorly understood; we know what crocodiles ingest, but not what nourishes them. In this study, we used a combination of stable isotope measurements (δ13C, δ15N, and δ34S) and direct feeding observations to identify the source of nutrition of estuarine crocodiles in Kakadu National Park, Northern Australia. Our results show that most crocodiles sampled (size 850 – 4200mm, with 76% of them being > 2.5 m) consume a large variety of prey, however a large proportion of their nutrition is derived from terrestrial prey. Introduced species such as water buffaloes (Bubalus bubalis) and pigs (Sus scrofa) could contribute between 53 and 84% to the nutrition of the sampled crocodiles. The isotopic composition of large crocodiles (total length > 3 m) suggested possible increase in marine prey consumption with size (R2 = 0.30; p = 0.005). Additionally, we found crocodiles sampled in the dry season had on average higher terrestrial contributions compared to crocodiles sampled during the wet season (84.1 ± 2.4% versus 55.4 ± 7.0%). Overall, we found that terrestrial prey are important source of nutrition for many crocodiles in this region where introduced herbivorous mammals are abundant.

When conservation becomes dangerous: Human‐Crocodile conflict in Timor‐Leste

ABSTRACTIn northern Australia and nearby Timor‐Leste, saltwater crocodile (Crocodylus porosus) populations were seriously depleted historically but recovered rapidly after protection: 1969–1974 in northern Australia, and 2000–2005 in Timor‐Leste. In both places, recovery caused increased rates of human‐crocodile conflict (HCC). Within northern Australia, the crocodile recovery and HCC have been documented over time. In contrast, this has not been the situation in Timor‐Leste, where we investigated HCC based on 130 attack records (1996–2014; 52% fatal). In 1996–2006, 0.55 attacks/year were reported in Timor‐Leste. By 2007–2014, 9 years later, a 23‐fold increase had occurred (13 attacks/year). Traditional subsistence fishing (82.5% of all attack records) is the highest risk activity, followed by bathing (7.5%) and water collecting (4.2%). Although the human population was correlated with crocodile attacks in Timor‐Leste, it likely does not explain the dramatic increase in crocodile attacks. Alternatively, crocodile numbers may have increased, either in the remnant resident crocodile population, or via migrants from elsewhere. Permanent crocodile habitat is limited, and limited breeding does not explain the high number of large crocodiles, and consequent increase in attacks in such a short time. A plausible explanation, consistent with traditional knowledge in Timor‐Leste, is that the influx of large crocodiles attacking people are migrants from Australia. We examined this possibility from available sources. Within Australia crocodiles have recovered since protection and they regularly invade adjacent habitats, such as Darwin harbor, where they are removed to prevent attacks on people. Saltwater crocodiles have been sighted at oil rigs, in the open ocean, moving between northern Australia and the south coast of Timor‐Leste. The likelihood of crocodiles migrating from Australia to Timor‐Leste raises obvious conservation, moral, and ethical dilemmas when conserving a large dangerous predator in one country to increase abundance results in dispersal to another country, where the predator attacks and kills people. © 2018 The Wildlife Society.

Quantifying species recovery and conservation success to develop an IUCN Green List of Species.

Stopping declines in biodiversity is critically important, but it is only a first step toward achieving more ambitious conservation goals. The absence of an objective and practical definition of species recovery that is applicable across taxonomic groups leads to inconsistent targets in recovery plans and frustrates reporting and maximization of conservation impact. We devised a framework for comprehensively assessing species recovery and conservation success. We propose a definition of a fully recovered species that emphasizes viability, ecological functionality, and representation; and use counterfactual approaches to quantify degree of recovery. This allowed us to calculate a set of 4 conservation metrics that demonstrate impacts of conservation efforts to date (conservation legacy); identify dependence of a species on conservation actions (conservation dependence); quantify expected gains resulting from conservation action in the medium term (conservation gain); and specify requirements to achieve maximum plausible recovery over the long term (recovery potential). These metrics can incentivize the establishment and achievement of ambitious conservation targets. We illustrate their use by applying the framework to a vertebrate, an invertebrate, and a woody and an herbaceous plant. Our approach is a preliminary framework for an International Union for Conservation of Nature (IUCN) Green List of Species, which was mandated by a resolution of IUCN members in 2012. Although there are several challenges in applying our proposed framework to a wide range of species, we believe its further development, implementation, and integration with the IUCN Red List of Threatened Species will help catalyze a positive and ambitious vision for conservation that will drive sustained conservation action.

Molecular characterization of the first saltwater crocodilepox virus genome sequences from the world\u2019s largest living member of the Crocodylia

Crocodilepox virus is a large dsDNA virus belonging to the genus Crocodylidpoxvirus, which infects a wide range of host species in the order Crocodylia worldwide. Here, we present genome sequences for a novel saltwater crocodilepox virus, with two subtypes (SwCRV-1 and -2), isolated from the Australian saltwater crocodile. Affected belly skins of juvenile saltwater crocodiles were used to sequence complete viral genomes, and perform electron microscopic analysis that visualized immature and mature virions. Analysis of the SwCRV genomes showed a high degree of sequence similarity to CRV (84.53% and 83.70%, respectively), with the novel SwCRV-1 and -2 complete genome sequences missing 5 and 6 genes respectively when compared to CRV, but containing 45 and 44 predicted unique genes. Similar to CRV, SwCRV also lacks the genes involved in virulence and host range, however, considering the presence of numerous hypothetical and or unique genes in the SwCRV genomes, it is completely reasonable that the genes encoding these functions are present but not recognized. Phylogenetic analysis suggested a monophyletic relationship between SwCRV and CRV, however, SwCRV is quite distinct from other chordopoxvirus genomes. These are the first SwCRV complete genome sequences isolated from saltwater crocodile skin lesions.

Pansteatitis Induced Differential Expression of Inflammatory and Apoptosis Genes in Adipose Tissue: A Glimpse into Pathophysiology of the Condition in the Nile Crocodile.

In the quest to understand the pathophysiology of pansteatitis in the Nile crocodile, a condition that was attributed to the recent crocodile die off at the Olifant river, Mpumalanga, the whole transcriptome of the Nile crocodile was sequenced and assembled using whole transcriptome shotgun sequencing data by Illumina RNAseq from RNA obtained from fat body and other adipose tissues.Total RNA, from abdominal fat body and other adipose tissue from normal farmed Nile crocodiles and samples collected from Nile crocodiles that had died of pansteatitis, were extracted and purified using Qiagen RNA mini prep (Qiagen, USA). RNA samples library were prepped using the Truseq stranded total RNA sample preparation and sequenced on the Illumina Hiseq 2500 with v4 SBS chemistry. Reads were assembled using Tophat (http://tophat.cbcb.umd.edu/) and aligned with reference transcriptome from Crocodylus porosus using Cufflinks (http://cufflinks.cbcb.umd.edu/) for downstream analysis while the differential gene expression analysis was done using Cuffdiff and RSEM (http://deweylab.github.io/RSEM/).A total of 13,329 genes were identified out which 1541 genes related to inflammatory response and apoptosis were identified. A total of 641 genes were up regulated in the pansteatitis samples as compared to normal adipose tissues using a fold change of 16.0. A total of 70 inflammatory genes were up regulated in the pansteatitis samples including, PDCD5 (programmed cell death 5), NFIL3 (nuclear factor, interleukin 3 regulated protein), HSP90B1 (heat shock protein 90kDa beta (Grp94), member 1), VCAM1 (vascular cell adhesion molecule 1), IL1R1 (interleukin 1 receptor, type I), TNIP1 (TNFAIP3 interacting protein 1), JAK1 (Janus kinase 1), TNFAIP2 (tumor necrosis factor, alpha‐induced protein 2) IL6ST (interleukin 6 signal transducer (gp130, oncostatin M receptor)) CFD (complement factor D (adipsin) and PPARG (peroxisome proliferator‐activated receptor gamma) among others. These genes are responsible for inflammation, apoptosis, regulation of Toll‐like receptors in inflammatory response, leucocyte migration and fibrosis in chronic inflammation.We present for the first time in the Nile crocodile, a comprehensive lists of inflammatory response genes that are expressed and up regulated in pansteatitis in the Nile crocodile.Support or Funding InformationPart of the study was funded by Tertiary Education Trust Fund (TETFund) AST and D, Nigeria and Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Measuring behavioral responses of sea turtles, saltwater crocodiles, and crested terns to drone disturbance to define ethical operating thresholds.

Drones are being increasingly used in innovative ways to enhance environmental research and conservation. Despite their widespread use for wildlife studies, there are few scientifically justified guidelines that provide minimum distances at which wildlife can be approached to minimize visual and auditory disturbance. These distances are essential to ensure that behavioral and survey data have no observer bias and form the basis of requirements for animal ethics and scientific permit approvals. In the present study, we documented the behaviors of three species of sea turtle (green turtles, Chelonia mydas, flatback turtles, Natator depressus, hawksbill turtles, Eretmochelys imbricata), saltwater crocodiles (Crocodylus porosus), and crested terns (Thalasseus bergii) in response to a small commercially available (1.4 kg) multirotor drone flown in Northern Territory and Western Australia. Sea turtles in nearshore waters off nesting beaches or in foraging habitats exhibited no evasive behaviors (e.g. rapid diving) in response to the drone at or above 20–30 m altitude, and at or above 10 m altitude for juvenile green and hawksbill turtles foraging on shallow, algae-covered reefs. Adult female flatback sea turtles were not deterred by drones flying forward or stationary at 10 m altitude when crawling up the beach to nest or digging a body pit or egg chamber. In contrast, flyovers elicited a range of behaviors from crocodiles, including minor, lateral head movements, fleeing, or complete submergence when a drone was present below 50 m altitude. Similarly, a colony of crested terns resting on a sand-bank displayed disturbance behaviors (e.g. flight response) when a drone was flown below 60 m altitude. The current study demonstrates a variety of behavioral disturbance thresholds for diverse species and should be considered when establishing operating conditions for drones in behavioral and conservation studies.

Apex predatory sharks and crocodiles simultaneously scavenge a whale carcass

Scavenging is an important component to the overall ecology of consumers in virtually all ecosystems on Earth. Given the energetic benefits of foraging on these resource subsidies, opportunistic predators will adjust their behaviors accordingly to maximize access. One of the many consequences of large-scale scavenging opportunities is species interactions that are rarely observed in nature. Here we describe the first published record of predatory sharks (tiger sharks, Galeocerdo cuvier) and saltwater crocodiles (Crocodylus porosus) foraging together in space and time, as documented on a large whale carcass off Western Australia. We report on and discuss the behaviors of the sharks and crocodiles in the hope of shedding new light on the interactions between apex predators that are rarely seen together, but may overlap under specific contexts.

Taphonomy ofIsisfordia duncanispecimens from the Lower Cretaceous (upper Albian) portion of the Winton Formation, Isisford, central-west Queensland

Taphonomic analysis of fossil material can benefit from including the results of actualistic decay experiments. This is crucial in determining the autochthony or allochthony of fossils of juvenile and adult Isisfordia duncani, a basal eusuchian from the Lower Cretaceous (upper Albian) distal-fluvial-deltaic lower Winton Formation near Isisford. The taphonomic characteristics of the I. duncani fossils were documented using a combination of traditional taphonomic analysis alongside already published actualistic decay data from juvenile Crocodylus porosus carcasses. We found that the I. duncani holotype, paratypes and referred specimens show little signs of weathering and no signs of abrasion. Disarticulated skeletal elements are often found in close proximity to the rest of the otherwise articulated skeleton. The isolated and disarticulated skeletal elements identified, commonly cranial, maxillary and mandibular elements, are typical of lag deposits. The holotype QM F36211 and paratype QM F34642 were classified as autochthonous, and the remaining I. duncani paratypes and referred specimens are parautochthonous. We propose that I. duncani inhabited upper and lower delta plains near the Eromanga Sea in life. Their carcasses were buried in sediment-laden floodwaters in delta plain overbank and distributary channel deposits. Future studies should refer to I. duncani as a brackish water tolerant species.

Double gene targeting PCR assay for the detection of Crocodylus porosus in commercial products

ABSTRACTThe demand for crocodile meat is quickly growing because of its exotic and organoleptic appeal and also the low content of cholesterol and lipids. Moreover, crocodile oil and blood have been used in alternative medicines for treating asthma and several other ailments since ancient times. Furthermore, crocodile hides have great demand in leather industries. All of these have collectively contributed to the extensive hunting, illegal trading and consequent decline of crocodiles in most parts of the world. To keep space with the growing demands, some crocodile species such as Crocodylus porosus have been raised in farms and its commercial trades have been legalised. However, demand for wild crocodiles in foods and medicines has continued in high gear. Recently, several DNA-based methods have been proposed for crocodile detection, but those assays are based on single gene and longer-sized amplicon targets that break down during extensive processing. To address this gap, here we developed and validated a highly stable double gene targeted multiplex PCR assay for the identification of C. porosus materials in commercial products. The assay involved two short sites from C. porosus atp6 (77 bp) and cytb (127 bp) genes and a universal internal control (99 bp) for eukaryotes. The PCR primers were cross-tested against 18 species and validated under pure and mixed matrices under extensive boiling, autoclaving and microwave cooking conditions. Finally, it was used to identify five crocodile-based commercial products. The lower limits of detection for atp6 and cytb genes were 0.001 ng and 0.01 ng DNA, respectively, in pure meat and 1% under mixed matrices. Some inherent features, such as 77–127 bp amplicon sizes, exceptional stability and superior sensitivity, suggested the assay could be used for the identification of C. porosus in any forensic specimen.

Comparative Analysis of Epidermal Differentiation Genes of Crocodilians Suggests New Models for the Evolutionary Origin of Avian Feather Proteins

The epidermis of amniotes forms a protective barrier against the environment and the differentiation program of keratinocytes, the main cell type in the epidermis, has undergone specific alterations in the course of adaptation of amniotes to a broad variety of environments and lifestyles. The epidermal differentiation complex (EDC) is a cluster of genes expressed at late stages of keratinocyte differentiation in both sauropsids and mammals. In the present study, we identified and analyzed the crocodilian equivalent of the EDC. The gene complement of the EDC of both the American alligator and the saltwater crocodile were determined by comparative genomics, de novo gene prediction and identification of EDC transcripts in published transcriptome data. We found that crocodilians have an organization of the EDC similar to that of their closest living relatives, the birds, with which they form the clade Archosauria. Notable differences include the specific expansion of a subfamily of EDC genes in crocodilians and the loss of distinct ancestral EDC genes in birds. Identification and comparative analysis of crocodilian orthologs of avian feather proteins suggest that the latter evolved by cooption and sequence modification of ancestral EDC genes, and that the amplification of an internal highly cysteine-enriched amino acid sequence motif gave rise to the feather component epidermal differentiation cysteine-rich protein in the avian lineage. Thus, sequence diversification of EDC genes contributed to the evolutionary divergence of the crocodilian and avian integuments.

Double gene targeting multiplex PCR-RFLP detects Crocodylus porosus in chicken meatball and traditional medicine

ABSTRACTCrocodiles have been hunted and consumed for centuries for skins, nutrients, and medicines. These indomitable trends have overpowered restrictions from wildlife and conservation agencies, continuing the illegal trades of crocodiles across the world. This paper described the development of a very stable, fast, and secured polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay for the confirmed detection of Crocodylus porosus under any matrices and decomposing treatments. Two very short-sites (77 and 127-bp) of atp6 and cytb genes of C. porosus were controlled digested with AciI enzyme; producing distinctive RFLP patterns (83, 54, 44 & 23 bp). The enzyme digested assay was stable following extreme boiling, autoclaving, and microwaving treatments that break down DNA. The sensitivity was tested and validated in model meatballs and it was suitable for detecting 0.01% crocodile meatball matrices. The optimized RFLP assay was used to screen 3 commercial meatballs and 21 traditional medicines (TM). While no crocodile DNA was found in commercial chicken meatballs, 4/21 TM products were found correctly labelled to contain C. porosus DNA. The novel assay demonstrated sufficient merit to be used by regulatory agencies for any forensic and/or archaeological identification of C. porosus even under the state of decomposition.

Mitigating the Human-Crocodile Conflict in Sri Lanka: A Study Based on the Nilwala River Area in Matara District

Human and crocodile have been coexisting for many years in Sri Lanka, particularly close to the Nilwala river area in Matara District, but fatalities were rarely reported. However, during the last decade the threats from crocodiles to humans have enhanced in the Nilwala river area, mainly during the years of 2005, 2008, 2009, 2012, 2013, 2014 and 2015. Some 26 attacks, killing 18 humans by saltwater crocodiles were recorded since 2000 in this area. In retaliation to these attacks, people in this area killed several crocodiles, and recorded the saltwater crocodile under the threatened category in Sri Lanka. Therefore, it is a worth to form a dialogue to mitigate human-crocodile conflict in the Nilwala river area in Sri Lanka. The Study was mainly based on primary and secondary data. Primary data was collected from semi-structured interviews. Sample size was consisted of forty-five (45) respondents. Secondary data was collected through published books, research reports, symposia proceedings, journal articles and web sites etc. Collected data from different sources, as mentioned above was analyzed using qualitative and quantitative methods, and it was presented using maps, texts, tables and figures. The study found that sand mining, population rise, using the river for daily needs such as drinking, bathing, washing clothes and fishing, unauthorized buildings in the river bank, scrub jungles, slow flowing of river are the major causes of the human-crocodile conflict in Nilwala river area. The study further found that Piladuwa, Fort and Thihagoda are the most vulnerable areas for human-crocodile conflict. "Kimbulkotuwa" or Crocodile Excluding Enclosure (CEEs) is a main method used to mitigate the human-crocodile conflict in this area.

Australia's Northern Safari

[Extract] Filmed during a 1955 family trip from Perth to the Gulf of Carpentaria, Keith Adams’s Northern Safari showed to packed houses across Australia, and in some overseas locations, across three decades. Essentially a home movie, initially accompanied by live commentary and subsequently by a homemade sound track, it tapped into audiences’ sense of Australia’s north as a place of adventure. In the film Adams interacts with the animals of northern Australia (often by killing them), and while by 1971 the violence apparent in the film was attracting criticism in letters to newspapers, the film remained popular through to the mid-1980s, and was later shown on television in Australia and the United States (Cowan 2; Adams, Crocodile Safari Man 261). A DVD is at present available for purchase from the website of the same name (Northern Safari). Adams and his supporters credited the film’s success to the rugged and adventurous landscape of northern Australia (Northeast vii), characterised by dangerous animals, including venomous spiders, sharks and crocodiles (see Adams, “Aussie”; “Crocodile”). The notion of Australia’s north as a place of rugged adventure was not born with Adams’s film, and that film was certainly not the last production to exploit the region and its wildlife as a source of excitement. Rather, Northern Safari belongs to a long list of adventure narratives whose hunting exploits have helped define the north of Australian as a distinct region and contrast it with the temperate south where most Australians make their lives. This article explores the connection between adventure in Australia’s north and the large animals of the region. Adams’s film capitalised on popular interest in natural history, but his film is only one link in a chain of representations of the Australian north as a place of dangerous and charismatic megafauna. While over time interest shifted from being largely concentrated on the presence of buffalo in the Northern Territory to a fascination with the saltwater crocodiles found more widely in northern Australia that interest in dangerous prey animals is significant to Australia’s northern imaginary.

Ecological and evolutionary significance of a lack of capacity for extended developmental arrest in crocodilian eggs.

Hypoxia within the oviducts maintains embryonic arrest in turtles at the pre-ovipositional stage, which expands the timeframe over which nesting can occur without compromising embryo survival. The arrest can be extended post-oviposition through incubation of eggs in hypoxia. We determined whether crocodilian embryos have this same capacity. We also tested whether increased oxygen availability during incubation alters hatching success. We incubated freshly laid saltwater crocodile (Crocodylus porosus) eggs (N = 83) at 32°C in one of five treatments; control (normoxia; 21% O2), 3-day and 6-day hypoxia (1% O2), or 3-day and 6-day hyperoxia (42% O2). Incubation (approx. 82 days) was then completed in normoxia. There was a significant effect of treatment on survival of embryos through to hatching (p < 0.001). The hypoxic treatments resulted in almost no hatching (6.7% and 0% survival for the 3- and 6-day treatments, respectively), while the hyperoxic and control treatments resulted in normal to high hatching success (86.6%, 100% and 64.2% for the control, 3- and 6-day hyperoxic treatments, respectively). Unlike turtles, hypoxic incubation of crocodile eggs failed to delay development. Our results provide the first experimental evidence that, unlike turtles, crocodiles do not exhibit embryonic arrest when incubated under hypoxic conditions immediately following oviposition. An absence of embryonic arrest is of ecological and evolutionary significance, as it implies that crocodilians lack an ability to avoid adverse environmental conditions through delayed nesting and that, unlike turtles, embryonic arrest may not be a potential explanation for the lack of viviparity in the order Crocodylia.

Increasing the length and hydrophobicity of the C-terminal sequence of transthyretin strengthens its binding affinity to retinol binding protein.

Transthyretin (TTR) is a transporter for thyroid hormone (TH) and retinol, the latter via binding with retinol binding protein (RBP). Both the N‐terminal and C‐terminal regions of the TTR subunit are located in close proximity to the central binding channel for ligands. During the evolution of vertebrates, these regions changed in length and hydropathy. The changes in the N‐terminal sequence were demonstrated to affect the binding affinities for THs and RBP. Here, the effects of changes in the C‐terminal sequence were determined. Three chimeric TTRs, namely pigC/huTTR (human TTR with the C‐terminal sequence changed to that of Sus scrofa TTR), xenoN/pigC/huTTR (human TTR with the N‐terminal and C‐terminal sequences changed to those of Xenopus laevis and S. scrofa, respectively), and pigC/crocTTR (Crocodylus porosus TTR with the C‐terminal sequence changed to that of S. scrofa TTR), were constructed and their binding affinities for human RBP were determined at low TTR/RBP molar ratio using chemiluminescence immunoblotting. The binding dissociation constant (K d) values of pigC/huTTR, xenoN/pigC/huTTR and pigC/crocTTR were 3.20 ± 0.35, 1.53 ± 0.38 and 0.31 ± 0.04 μm, respectively, and the K d values of human and C. porosus TTR were 4.92 ± 0.68 and 1.42 ± 0.45 μm, respectively. These results demonstrate chimeric TTRs bound RBP with a higher strength than wild‐type TTRs, and the changes in the C‐terminal sequence of TTR had a positive effect on its binding affinity for RBP. In addition, changes to the N‐terminal and C‐terminal sequences showed comparable effects on the binding affinity.