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Northern leopard frog

The Northern leopard frog (Lithobates pipiens), also known as the meadow frog or spotted frog, is a medium-sized, semi-aquatic anuran species characterized by its slender body, smooth greenish-brown to yellow-green dorsal skin, and prominent large, oval black spots with pale borders, often arranged in rows along the back.^[1] Adults typically measure 2 to 4.5 inches (5–11 cm) in snout-vent length, with long hind legs adapted for jumping and swimming, a white belly, and a distinctive white stripe along the upper lip.^[1] Tadpoles are dark olive to brown, with a total length up to 4 inches (10 cm), feeding primarily on algae and detritus.^[2] Native to much of North America, the northern leopard frog inhabits a range spanning from the northeastern United States and Canada westward to the Rocky Mountains, including wetlands, marshes, slow-moving streams, ponds, and moist meadows, where it requires access to both aquatic breeding sites and terrestrial foraging areas.^[1] It is semi-aquatic, spending summers in grassy fields near water and overwintering in deeper, oxygenated permanent waters to avoid freezing.^[3] The species breeds in spring (March to May), with males producing a distinctive rattling snore call to attract females, who lay clusters of 500 to 6,000 eggs in shallow, vegetated waters; eggs hatch in 1–3 weeks, and tadpoles metamorphose into froglets after 2–4 months.^[2] Adults are opportunistic carnivores, preying on insects, spiders, snails, and occasionally small vertebrates like other frogs or minnows.^[1] Once widespread, northern leopard frog populations have experienced significant declines since the mid-20th century, particularly in western regions, due to habitat loss from agriculture and urbanization, pollution, introduced predators, and diseases such as chytrid fungus.^[1] It is listed as a species of concern in several U.S. states (e.g., endangered in Washington, species of conservation concern in Missouri), with fragmented distributions and ongoing conservation efforts including habitat restoration and reintroduction programs.^[4]^[3] The species is assessed as least concern on the IUCN Red List (2022), though many populations continue to decline.^[5] The frog's adaptability and role in ecosystems as both predator and prey highlight its ecological importance, though climate change and chemical contaminants pose continued threats.^[2]

Taxonomy and nomenclature

Etymology and common names

The binomial name Lithobates pipiens derives from Greek and Latin roots. The genus name Lithobates combines the Greek words lithos (λίθος), meaning "stone," and bates (βάτης), meaning "one that treads" or "walker," referring to the frog's tendency to inhabit rocky areas near water.^[6] The specific epithet pipiens is the present participle of the Latin verb pipio, meaning "to peep" or "to chirp," alluding to the species' distinctive advertising call.^[7] The species was originally named Rana pipiens by Carl Linnaeus in 1758 in the tenth edition of Systema Naturae, based on specimens from North America, though the valid description is attributed to Johann Christian Daniel von Schreber in 1782.^[8] In a major taxonomic revision, it was reclassified into the genus Lithobates by Frost et al. in 2006 to better reflect phylogenetic relationships among North American true frogs.^[8] Common names for Lithobates pipiens include Northern leopard frog, a reference to its dorsal spots resembling those of a leopard; meadow frog; and grass frog, reflecting its frequent occurrence in open grassy habitats away from permanent water during non-breeding periods.^[9] Regional variations exist, such as "leopard frog" more generally in parts of the United States and Canada.

Classification and synonyms

The Northern leopard frog (Lithobates pipiens) is placed within the order Anura, family Ranidae (true frogs), genus Lithobates, reflecting its position among the New World clade of ranid frogs. Close relatives include the Southern leopard frog (Lithobates sphenocephalus), with which it shares phylogenetic affinities within the genus based on molecular and morphological data.^[10]^[1]^[11] Phylogenetic analyses using mitochondrial DNA sequences indicate that L. pipiens diverged from Old World Rana species through ancient dispersals from East Asia to North America via Beringian land bridges, with the broader radiation of New World true frogs occurring during the Miocene. Within L. pipiens itself, molecular data reveal a major phylogeographic split between eastern and western populations approximately 2 million years ago, associated with Pleistocene glaciation events.^[12]^[11]^[13] First validly described as Rana pipiens by Johann Christian Daniel von Schreber in 1782, although the name was first proposed by Carl Linnaeus in 1758, the species has a complex taxonomic history tied to the broader Rana pipiens complex of leopard frogs. A homotypic synonym is Pantherana pipiens, reflecting early generic proposals. For much of the 20th century, northern populations were classified as the subspecies Rana pipiens pipiens, while southern variants were treated as R. p. berlandieri (now the distinct species Lithobates berlandieri) and R. p. blairi (now L. blairi), based on differences in morphology, vocalizations, and distribution.^[14]^[15]^[16] In a landmark 2006 revision, Frost et al. restructured amphibian phylogeny using extensive molecular and morphological evidence, elevating Lithobates as a distinct genus for New World ranids previously lumped under Rana to better reflect monophyletic lineages; this change, while debated, is widely adopted in modern taxonomy. Some sources, such as AmphibiaWeb, suggest using the hybrid nomenclature Rana (Lithobates) pipiens to maintain stability with traditional usage.^[17]^[18]^[19] No subspecies are currently recognized for L. pipiens, as former designations have been resolved into full species within the pipiens complex.^[17]^[18]

Physical characteristics

Morphology and size

The Northern leopard frog (Lithobates pipiens) is a medium-sized true frog, with adults typically measuring 5–11 cm (2–4.5 inches) in snout-vent length (SVL), though females are generally larger than males.^[2]^[20] Key morphological features include smooth, glandular skin; long, powerful hind legs capable of jumping up to 20 times the body length; fully webbed hind toes for swimming; a prominent, circular tympanum (eardrum) visible behind each eye; and raised, light-colored dorsolateral folds extending from behind each eye along the back to the groin.^[21]^[22]^[3] Sexual dimorphism is pronounced during the breeding season, when males develop paired external vocal sacs for calling and exhibit throat enlargement.^[21] In the larval stage, tadpoles are herbivorous, featuring specialized keratinized mouthparts for grazing on algae and microorganisms, along with a dorsoventrally flattened body and a large, translucent tail fin for aquatic locomotion. Metamorphosis from tadpole to juvenile typically takes 2–3 months under favorable conditions.^[21]^[2]

Coloration and patterns

The Northern leopard frog (Lithobates pipiens) displays a dorsal background color that varies from bright green to brown or occasionally yellow-green, accented by large, irregular dark spots that evoke the pattern of a leopard.^[1] Each spot is typically rounded or oval and bordered by a pale halo, creating a mottled appearance on the smooth skin, while the ventral surface is uniformly white to creamy, sometimes with subtle yellow tinges or pinkish patches on the thighs and feet.^[2]^[23] Geographic variation influences this coloration, with greener dorsal hues more prevalent in northern or forested populations, potentially aiding integration with lush vegetation, whereas southern or prairie populations tend toward browner tones that match drier, open landscapes.^[24] Spotting patterns also differ regionally, becoming more extensive and irregular in warmer, moister southern climates compared to the sparser, more defined spots in northern areas.^[24] Seasonally, individuals darken significantly during winter hibernation or upon emergence in spring, often appearing nearly black due to expanded pigmentation under low temperatures.^[25] These color shifts are regulated by chromatophores, particularly melanophores, which contain melanin granules that disperse or aggregate in response to hormonal signals like α-melanocyte-stimulating hormone (α-MSH), enabling physiological adjustments to environmental backgrounds or thermal conditions.^[26]^[27] The overall coloration and spotting serve primarily as cryptic camouflage, allowing the frog to blend seamlessly with heterogeneous wetland and grassland substrates, thereby reducing predation risk, though the species exhibits a relatively constrained polymorphism compared to more variable anurans like certain tree frogs.^[10]^[28]

Distribution and habitat

Geographic range

The Northern leopard frog (Lithobates pipiens) has a broad native range across North America, extending from the Arctic regions of Canada, including areas around Great Slave Lake, Hudson Bay, and Labrador, southward through the United States to southern Arizona and New Mexico, and eastward to the Atlantic coast while reaching westward to the Rocky Mountains, with spotty distributions in the Pacific Northwest including eastern Washington, Oregon, and California.^[29]^[30] The species has been introduced or reintroduced in several western U.S. localities, such as parts of California and the Greater Yellowstone ecosystem, to bolster populations where native occurrences have diminished.^[29]^[4] Historically, the northern leopard frog was widespread across much of its range prior to the early 20th century, occupying continuous distributions from the prairies and lowlands of the Midwest to montane areas in the Rockies.^[31] However, significant declines have occurred since the 1970s, particularly in the southern United States (including near-extirpation in Texas and parts of the Southwest) and the prairie provinces of Canada, as well as in western states like Washington, Oregon, and Colorado, leading to fragmented and reduced extents in those regions.^[31]^[4] Despite these losses, the species remains relatively common in many eastern and central lowland areas, with an overall range extent exceeding 2,500,000 km².^[29] The northern leopard frog occupies elevations from sea level up to approximately 3,500 meters in mountainous regions, such as the Rockies, where breeding timing shifts later at higher altitudes.^[19] Dispersal occurs primarily overland, with individuals capable of migrating up to 1 km between wetlands, though movements are often limited by barriers like highways and unsuitable terrain.^[31]^[32]

Habitat preferences

The Northern leopard frog (Lithobates pipiens) inhabits a variety of wetland and adjacent terrestrial environments across its range, favoring permanent ponds, marshes, slow-moving streams, and temporary pools that support its life stages. These frogs are commonly associated with shallow, vegetated aquatic habitats such as beaver ponds, stock tanks, and borrow pits lacking predaceous fish, as well as emergent vegetation in wetlands including sedges and rushes. Terrestrial preferences include damp grasslands, wet meadows, and open fields near water margins, often in agricultural or prairie landscapes, where they exploit mosaics of aquatic and upland areas for feeding and dispersal.^[31]^[2]^[30] In terms of microhabitat use, adults and juveniles spend daytime hours concealed under vegetation, leaf litter, or submerged in shallow water to avoid desiccation and predators, while emerging at night to forage in open, grassy areas with short vegetation (6 inches to 1 foot high). Breeding occurs exclusively in shallow, warm waters with rooted aquatic plants, such as those in marshes or temporary pools, where tadpoles select still backwaters for development. Dispersal relies on corridors like vegetated ditches and floodplain edges, with juveniles traveling up to 0.5 miles from natal sites.^[31]^[2]^[30] Northern leopard frogs exhibit temperature tolerance suited to temperate climates, remaining active when water temperatures reach 10–25°C and initiating breeding at 14–23°C, with optimal conditions around 15–25°C for foraging and growth. They hibernate during winter in oxygenated, non-freezing aquatic sites, such as the bottoms of ponds, lakes, or streams, often burrowing into mud, under rocks, logs, or in shallow pits to withstand low temperatures down to near freezing.^[2]^[30]^[33] While avoiding dense forests, these frogs tolerate human-modified habitats, including farm edges, irrigation ditches, and agricultural meadows adjacent to wetlands, which provide suitable open foraging areas and breeding opportunities in constructed ponds.^[31]^[2]

Ecology and life history

Diet and foraging behavior

The Northern leopard frog (Lithobates pipiens) exhibits an opportunistic diet, with adults and juveniles primarily consuming invertebrates such as insects (including beetles and flies), arachnids, worms, snails, and crustaceans, while occasionally preying on small vertebrates like fish and other amphibians.^[34]^[35] Tadpoles, in contrast, are mainly herbivorous, grazing on algae, phytoplankton, periphyton, and detritus, which supports their role in aquatic nutrient cycling.^[34]^[36] Foraging behavior in adults relies on a sit-and-wait ambush strategy, where individuals perch motionless in vegetation or on moist ground, using keen visual detection to identify prey before striking with a rapid tongue projection that can extend up to 1.5 times the body length.^[37]^[38] This method allows efficient capture of mobile prey without excessive energy expenditure, often supplemented by short leaps if needed.^[39] Seasonal variations influence prey selection, with summer foraging favoring aquatic or semi-aquatic items due to increased activity near ponds and wetlands, shifting toward more terrestrial invertebrates like insects and worms in the fall as frogs move to upland habitats.^[31]^[40] As a mid-level predator, the Northern leopard frog plays a key role in food webs by controlling populations of herbivorous and pest insects, thereby influencing ecosystem dynamics in wetlands and meadows.^[41]^[10]

Reproduction and development

The breeding season for the Northern leopard frog (Lithobates pipiens) typically occurs in spring, from April to June, though it varies by latitude and local climate, with migrations to breeding sites beginning in mid- to late March in southern regions.^[42] Breeding is triggered when water temperatures exceed 10°C (50°F), prompting males to gather in choruses at shallow ponds or wetlands.^[42] Males produce advertisement calls—a rattling or snoring trill lasting 2–3 seconds—to attract females, often forming dense aggregations in warm, open water areas without territorial defense.^[43]^[44] Mating involves axillary amplexus, where the male clasps the female around the torso, lasting approximately 24 hours until egg deposition.^[42] Fertilization is external: females release eggs into the water, which the male fertilizes simultaneously.^[31] Each female lays a single clutch of 2,000–6,500 eggs, forming a spherical jelly mass 5–10 cm in diameter, typically attached to submerged vegetation or the pond bottom in shallow water (less than 1 m deep).^[42]^[4] Clutches may be laid individually or in communal rafts of 25–40 masses.^[42] There is no parental care after egg-laying; adults disperse shortly thereafter.^[42] Eggs hatch into tadpoles after 13–20 days, depending on water temperature, with warmer conditions accelerating development.^[42] Tadpoles are herbivorous, grazing on algae and detritus, and grow to lengths of up to 84 mm over 60–80 days in southern populations.^[42] The larval period (time to metamorphosis) typically lasts 70–110 days, extending longer at higher latitudes due to cooler temperatures and shorter growing seasons.^[42]^[10] Metamorphosis produces juveniles measuring 20–30 mm, which then disperse to upland habitats.^[42] Early life stages experience high mortality, with survival from egg to adult often below 5% due to predation, desiccation, and disease.^[42]^[45]

Behavior and interactions

Activity patterns and locomotion

The Northern leopard frog (Lithobates pipiens) exhibits a flexible activity pattern that combines diurnal and nocturnal behaviors, allowing it to forage and move effectively across varied environmental conditions. Individuals are active both during the day and at night, with activity levels peaking at dawn and dusk when temperatures are cooler and humidity is higher, facilitating efficient thermoregulation and reducing desiccation risk.^[46]^[47] In northern portions of its range, the species enters hibernation in October or November and remains dormant until March or April, typically submerging in oxygen-rich, unfrozen water bodies such as ponds, streams, or lakes to survive freezing temperatures.^[42]^[33] Locomotion in the Northern leopard frog is characterized by powerful, explosive jumps on land, efficient swimming in aquatic environments, and deliberate walking over short distances. Adults can achieve jumps of up to 1.8 meters—approximately 10 to 20 times their body length—propelled by rapid contraction of hindlimb muscles, with takeoff velocities reaching around 2 m/s and accelerations generating forces up to four times body weight during the propulsive phase.^[48]^[22]^[49] In water, they employ alternating strokes of their webbed hind legs for propulsion, while on land, they walk or hop in a zigzag pattern to navigate terrain and pursue prey. These jumping capabilities also support foraging, enabling quick strikes on mobile insects.^[50] Sensory adaptations enhance the frog's locomotor efficiency and environmental responsiveness. Tadpoles rely on the lateral line system—a network of mechanoreceptors along the body—to detect subtle water movements, aiding navigation and predator avoidance in aquatic habitats.^[33] In adults, keen visual acuity allows detection of prey across a wide field of view, including 360 degrees at ground level, supporting precise jumps and orientation during activity peaks.^[51] Seasonally, Northern leopard frogs undertake short-distance migrations, often up to 2 kilometers, from summer foraging areas to overwintering sites in late fall, ensuring access to suitable hibernation locations while minimizing energy expenditure.^[50]^[45]

Predation and defense mechanisms

The Northern leopard frog (Lithobates pipiens) faces predation across all life stages from a diverse array of vertebrates. Adults and juveniles are commonly preyed upon by birds such as great blue herons (Ardea herodias) and red-tailed hawks (Buteo jamaicensis), as well as mammals including raccoons (Procyon lotor), mink (Neovison vison), and skunks (Mephitis mephitis).^[22] Snakes, particularly garter snakes (Thamnophis spp.), and larger amphibians like American bullfrogs (Lithobates catesbeianus) also target adults and juveniles.^[52]^[21] Tadpoles are especially vulnerable to aquatic predators, including fish such as bass (Micropterus spp.), pike (Esox lucius), and introduced species like mosquitofish (Gambusia affinis), as well as predatory insects like dragonfly nymphs.^[22]^[4] These interactions highlight the frog's position in the food web, where it serves as a key prey item for maintaining predator populations.^[53] To counter these threats, northern leopard frogs employ a combination of morphological, chemical, and behavioral defenses. Their cryptic coloration, featuring dark spots on a green or brown background, provides camouflage against visual predators like birds by blending with aquatic vegetation and leaf litter.^[54] Skin secretions from granular glands offer chemical protection through low-level toxic alkaloids, which are diet-derived lipid-soluble compounds that deter some predators by inducing unpalatability or mild irritation.^[55] Behaviorally, individuals often freeze in place to avoid detection or rapidly flee to aquatic refuges or dense vegetation, leveraging their powerful hind legs for quick leaps that can exceed 2 meters.^[9]^[42] These strategies are most effective in heterogeneous habitats with cover, though they provide limited defense against invasive predators like bullfrogs, to which the species has not evolved strong countermeasures.^[45] Predation exerts significant pressure on northern leopard frog populations, particularly during early life stages, where it accounts for the majority of mortality. Tadpole and juvenile survival is low, with overall mortality rates often exceeding 90-98% in the first few months post-metamorphosis due to intense predation alongside environmental factors.^[37]^[56] This high juvenile attrition shapes the species' r-selected life history, characterized by large clutch sizes to offset losses, but it also contributes to population declines in areas with elevated predator densities or habitat fragmentation.^[45]

Conservation status

Population trends

The Northern leopard frog (Lithobates pipiens) exhibits varied population trends across its range, remaining stable or common in northern and eastern portions of North America while experiencing significant declines in western regions. In the eastern United States and Canada, populations are generally widespread and secure, with no evidence of broad-scale reductions, though localized contractions have been noted in areas like the Great Lakes basin.^[24] Conversely, since the 1960s, western U.S. and Canadian populations have declined markedly, with losses estimated at 70-90% in many areas due to historical extirpations and range contractions; for instance, Alberta populations historically declined to about 20% of historical sites occupied by 2001, though reintroduction efforts have since improved occupancy and established new populations.^[57]^[24]^[58] The species holds a global IUCN Red List status of Least Concern, reflecting its overall abundance, but it is locally vulnerable or endangered in western subpopulations, such as those in the Rocky Mountains.^[57] Monitoring efforts through the North American Amphibian Monitoring Program (NAAMP) have documented these patterns, revealing range contractions particularly in the western U.S., where calling surveys indicate reduced occupancy at historical sites across states like Montana and Washington.^[59] In healthy wetlands, egg mass densities often reach several hundred per hectare in optimal conditions.^[2]^[29] Primary factors influencing these trends include habitat loss, which has driven most declines, alongside disease outbreaks; however, some recovery has occurred in reintroduced sites, such as the Columbia Marshes in British Columbia, where captive-bred individuals have established breeding populations.^[24]^[60] Ongoing monitoring and reintroduction programs continue to track and bolster these dynamics, with stable northern populations providing a buffer against further range-wide vulnerability.^[59]

Threats and conservation efforts

The Northern leopard frog faces multiple anthropogenic and environmental threats that have contributed to population declines across its range. Habitat destruction and degradation, primarily from agricultural expansion, urbanization, and wetland drainage, fragment breeding and foraging areas, reducing available permanent water bodies and upland refugia essential for the species' survival.^[61]^[62] Pesticide exposure, particularly to herbicides like atrazine, induces sublethal effects such as immunosuppression in adults and developmental abnormalities in larvae, including gonadal malformations that impair reproduction.^[63]^[19] These chemicals also increase susceptibility to pathogens by weakening immune responses. The chytrid fungus Batrachochytrium dendrobatidis (Bd) represents a primary infectious threat, causing chytridiomycosis, which leads to skin infections, electrolyte imbalances, and high mortality rates, especially in post-metamorphic stages. Post-2020 monitoring indicates ongoing Bd prevalence in remnant populations, with infection rates remaining a barrier to recovery despite some natural resistance in survivors; for instance, treatments have reduced infection from 75% to 9% in captive groups, highlighting persistent impacts.^[64] Climate change exacerbates these vulnerabilities by altering hydrology through increased droughts and warmer temperatures, which dry breeding wetlands, shift phenology, and potentially expand Bd's range by favoring its optimal growth conditions.^[65]^[66] Conservation efforts focus on mitigating these threats through habitat protection, disease management, and population augmentation. Wetland restoration initiatives by the U.S. Fish and Wildlife Service involve removing invasive species like bullfrogs and cattails, replanting native vegetation such as soft-stem bulrush, and controlling water levels to eliminate non-native egg masses, thereby reducing competition and disease transmission.^[67]^[68] In Canada, captive breeding programs at facilities like the Wilder Institute and Valley Zoo produce thousands of individuals annually for reintroduction, with protocols including head-starting tadpoles to improve survival rates.^[69]^[70] Regulatory measures since the 1990s, including federal reviews of pesticides like atrazine under the Endangered Species Act, aim to limit contamination in aquatic habitats, though enforcement varies by jurisdiction.^[71] Protected areas such as national parks provide safeguards; for example, populations in Yellowstone National Park benefit from habitat preservation, while reintroduction successes in Arizona's livestock tanks and western Canadian sites have established self-sustaining groups through translocation of over 4,000 individuals since 2010.^[2]^[72] Recent milestones as of 2025 include the establishment of self-sustaining populations in Alberta through provincial reintroductions and the first documented winter survival of released frogs in Washington state.^[58]^[73] These efforts underscore the need for continued monitoring of Bd and climate-driven habitat loss to address recovery gaps.^[65]

Scientific research

Medical applications

The Northern leopard frog (Lithobates pipiens, formerly Rana pipiens) has been employed in biomedical research since the mid-20th century. More prominently, since the 1970s, the species has served as a key model in toxicology to assess pesticide effects on amphibian health, with ongoing research examining impacts on immune function, development, and reproduction from contaminants like neonicotinoids and organophosphates.^[74]^[75] In disease modeling, Northern leopard frogs have facilitated teratogen studies, where exposure to pollutants such as methoprene and ultraviolet light induces limb deformities, providing insights into environmental causes of malformations observed in wild populations.^[76]^[77] For cancer research, ribonucleases extracted from the oocytes of Northern leopard frogs, notably onconase (ranpirnase) and amphinase, have shown antitumor activity by degrading RNA in malignant cells, leading to cell cycle arrest and apoptosis; these compounds have advanced to clinical trials for treating various cancers, including malignant mesothelioma and brain tumors. As of 2025, onconase remains in Phase III clinical trials for malignant mesothelioma and other cancers, with mixed efficacy results under evaluation.^[78]^[79]^[80] Advantages of using Northern leopard frogs in such research include their large egg size (approximately 1.5–2 mm diameter), which allows for easy microinjection and manipulation during early developmental stages, and their rapid metamorphosis (typically 60–90 days under optimal conditions), enabling efficient study of toxicological and pharmacological effects.^[10] However, post-2000s ethical considerations, aligned with the 3Rs principles (replacement, reduction, refinement), alongside the species' declining populations and conservation status in many regions, have prompted a shift toward alternative models like in vitro assays and zebrafish for similar applications.^[81]^[82] Key findings from 1990s and early 2000s research include demonstrations that low-level exposure to the herbicide atrazine (≥0.1 ppb) induces gonadal dysgenesis and hermaphroditism in Northern leopard frogs, effects that prompted the U.S. Environmental Protection Agency (EPA) to review and impose restrictions on atrazine use to mitigate endocrine disruption in wildlife.^[83]

Neuroscience studies

Research on the Northern leopard frog (Lithobates pipiens, formerly Rana pipiens) has significantly contributed to understanding auditory processing in anurans, particularly through studies of vocalization and mate recognition. Auditory brainstem responses (ABRs) to conspecific calls reveal rapid neural encoding of advertisement calls, with ABR waveforms showing peaks tuned to the dominant frequencies of these calls, enabling quick detection during breeding choruses.^[84] Neural circuits underlying mate recognition involve the dorsal medullary nucleus (DMN) and central nucleus of the torus semicircularis, where single-unit recordings demonstrate selective responses to temporal patterns in calls, such as pulse rates and durations characteristic of L. pipiens snores and trills.^[85] These circuits facilitate species-specific phonotaxis, with electrical stimulation of the preoptic area and brainstem eliciting calling correlates that mimic natural mate attraction behaviors.^[86] During metamorphosis, thyroid hormones (THs) orchestrate extensive brain remodeling in L. pipiens tadpoles, influencing neurogenesis, neuronal differentiation, and apoptosis to adapt the neural architecture from aquatic to terrestrial life. TH receptors (TRα and TRβ) exhibit dynamic expression in the developing brain, peaking during prometamorphosis and climax stages to regulate gene transcription for synaptic pruning and circuit reorganization.^[87] Exposure to exogenous TH accelerates these processes, increasing neuronal death in specific regions while promoting differentiation in others, such as the optic tectum and auditory nuclei, ensuring functional maturation of sensory systems.^[88] Cross-regulation with estrogen receptors further modulates these effects, highlighting TH's role in integrating endocrine signals for neural plasticity.^[89] Seminal experiments from the 1980s and 1990s on the optic tectum elucidated its central role in visual prey detection, with ablation studies showing that tectal lesions abolish orienting responses to stationary or moving prey stimuli, while sparing obstacle avoidance.^[90] Electrophysiological recordings from eighth nerve fibers and midbrain neurons during this era revealed frequency tuning curves optimized for conspecific calls, with best sensitivities between 500 and 2000 Hz, matching the spectral bandwidth of L. pipiens advertisement calls (dominant energy 500–1500 Hz).^[91] These V-shaped tuning functions, characterized by thresholds as low as 30–50 dB SPL, underscore the tectum's integration of auditory and visual inputs for predator avoidance and foraging.^[92] Recent advances in L. pipiens neuroscience include exploratory applications of optogenetics to map vocal and motor circuits, though such techniques remain less prevalent than in Xenopus laevis models due to challenges in genetic manipulation. Optogenetic stimulation of dopamine D1 receptors in tectal pathways has demonstrated enhanced motor responses to visual cues, building on classical electrophysiology to dissect causal neural mechanisms.^[93] These methods promise finer resolution for studying plasticity in metamorphosis-related circuits, complementing traditional approaches in revealing how environmental factors influence neural development.^[94]

Muscle physiology and biomechanics

The Northern leopard frog (Lithobates pipiens) possesses a muscular system adapted for explosive locomotion, particularly jumping, with hindlimb muscles dominated by fast-twitch fibers. These fibers express predominantly type 1 myosin heavy chain isoforms, optimized for anaerobic metabolism and quick contraction velocities. In contrast, muscles involved in sustained activities like swimming, such as portions of the iliofibularis, incorporate slow-twitch fibers that support prolonged, low-intensity contractions through higher mitochondrial density and oxidative capacity.^[95] Biomechanical analyses of jumping in L. pipiens reveal efficient force generation and kinematics tailored for maximizing distance. During takeoff, the hindlimbs produce peak ground reaction forces equivalent to approximately 10 times body weight, primarily through coordinated extension of the knee and ankle joints.^[49] Kinematic studies show takeoff angles typically ranging from 30° to 55° relative to the horizontal, with an average of about 54° in near-maximal jumps exceeding 50 cm (over 9 times body length), allowing for optimal trajectory and minimal energy loss.^[49] Mathematical models of these jumps incorporate muscle-tendon unit dynamics, where tendons act as elastic buffers, storing and releasing energy to enhance power output from the plantaris longus, which peaks at around 536 W/kg during propulsion.^[49] Physiological investigations highlight the role of calcium dynamics in sarcomere activation within L. pipiens muscle fibers. Calcium ions bind to troponin, initiating cross-bridge cycling between actin and myosin filaments, with intra-sarcomeric gradients ensuring rapid and spatially controlled force development during twitches.^[96] Compared to mammalian skeletal muscle, frog fast-twitch fibers exhibit greater fatigue resistance in short-term high-power tasks due to higher sarcoplasmic reticulum calcium stores and slower metabolite accumulation, though they trade off endurance for explosive performance.^[97] Research on L. pipiens muscle physiology traces back to foundational work in the 1960s, where frog sartorius muscles informed the sliding filament theory of contraction, earning Andrew F. Huxley and Hugh E. Huxley the 1963 Nobel Prize in Physiology or Medicine for elucidating actin-myosin interactions. This species remains a model for such studies due to its accessible, intact fiber preparations. Insights from these mechanics have influenced bio-inspired robotics, where frog-like tendon elasticity and power amplification are replicated in jumping mechanisms for enhanced mobility in soft robots.^[98]

References

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Northern Leopard Frog (Lithobates pipiens) | U.S. Fish & Wildlife ...
Northern leopard frogs breed in a variety of aquatic habitats that include slow-moving or still water along streams and rivers, wetlands, permanent or temporary ...
[2]
Northern Leopard Frog - Montana Field Guide
Sep 30, 2024 · Northern Leopard Frogs are present mostly across the prairies of the eastern two-thirds of the state while the Columbia Spotted Frog and most ...
[3]
Northern Leopard Frog - Missouri Department of Conservation
In its overall range in the northern and eastern United States and Canada, it lives in or near marshes, flooded ditches, floodplain pools and small ponds, and ...
[4]
Northern leopard frog | Washington Department of Fish & Wildlife
Northern leopard frogs are semi-aquatic, requiring both aquatic and terrestrial habitats. Breeding occurs in shallow, still water. Typically these areas are ...
[5]
American Water Frogs (Genus Lithobates) - iNaturalist
Lithobates is a subgenus or genus of true frogs, of the family Ranidae. The name is derived from litho- (stone) and the Greek bates (βάτης, one that treads).
[6]
Northern Leopard Frog - Kansas Herpetofaunal Atlas
From Latin pipio, “to chirp” or “to peep.” The present participle pipiens means “peeping,” referring to the frog's vocalizations.
[7]
Lithobates pipiens (Schreber, 1782) - Amphibian Species of the World
Coined by Linnaeus as a junior synonym of Rana ocellata Linnaeus, 1758 (now = Osteopilus ocellatus) and attributed to Kalm in error (as the name employed by ...Missing: Carl | Show results with:Carl
[8]
Northern Leopard Frog - Hinterland Who's Who
The Northern Leopard Frog (Lithobates pipiens) is named for its leopard-like spots across its back and sides. Another common name for this frog is the 'meadow ...Missing: etymology | Show results with:etymology
[9]
Lithobates pipiens (Northern Leopard Frog) - Animal Diversity Web
They are commonly known as meadow frogs or grass frogs because they tend to stray far from the water when it is not breeding season. They prefer open areas to ...
[10]
Spatiotemporal Diversification of the True Frogs (Genus Rana)
Our analyses consistently support an “Out of Asia” pattern with two independent dispersals of Rana from East Asia to North America via Beringian land bridges.<|separator|>
[11]
[PDF] evolutionary history of the northern leopard frog: reconstruction
The study uses phylogenetic, phylogeographic, and demographic analyses to understand the northern leopard frog's history, finding eastern/western haplotypes ...
[12]
(PDF) Evolutionary history of the northern leopard frog - ResearchGate
This study uses a combined methodological approach including phylogenetic, phylogeographic, and demographic analyses to understand the evolutionary history ...
[13]
Taxonomy browser (Lithobates pipiens) - NCBI
Lithobates pipiens (Schreber, 1782) basionym: Rana pipiens Schreber, 1782 homotypic synonym: Pantherana pipiens Genbank common name: northern leopard frog.
[14]
Rana Pipiens Complex: Mating Call Structure and Taxonomy
Geographic variability in call structure indicates that four largely allopatric populations of leopard frogs are present in the central United States.
[15]
Northern Leopard Frog - INHS Herpetology Collection
AmphibiaWeb recommends using Rana (Lithobates) pipiens to demonstrate that it is a member of the subgenus Lithobates while preserving long-standing taxonomy.
[16]
https://herpetology.inhs.illinois.edu/resources/species-lists/ilspecies/northern-leopard-frog/
[17]
Phylogenetic relationships of leopard frogs (Rana pipiens complex ...
We show that frogs from the Sierra El Aguaje belong to the Rana berlandieri subgroup, or Scurrilirana clade, of the R. pipiens group, and are most closely ...Missing: taxonomy | Show results with:taxonomy
[18]
Northern leopard frog | Minnesota DNR
Length: Typically, 2 to 3.5 inches. Color: Brown or green with two or three rows of irregularly spaced dark spots. Spots are rounded and have light borders.
[19]
[PDF] Northern Leopard Frog - Boulder County
Their aquatic habitat is characterized by lack of bedrock, sandy shoreline, and extensive vegetation (usually sedges/rushes). The northern leopard frog was ...
[20]
[PDF] Northern Leopard Frog
One adaptation to this predation is that frogs are powerful swimmers and jumpers, leaping 5 to 6 feet in a zig-zag pattern to avoid capture.
[21]
Northern Leopard Frog :: University of Wyoming Biodiversity Institute
Northern Leopard Frog (Lithobates pipiens) · Wood Frog (Lithobates sylvaticus) · Columbia Spotted Frog (Rana luteiventris) · Boreal Chorus Frog (Pseudacris ...
[22]
[PDF] Northern Leopard Frog (Lithobates pipiens)
The species name. "pipiens" comes from the erroneous association of this frog with the call of the Spring. Peeper, Pseudacris crucifer, which is small frog that ...
[23]
[PDF] Northern Leopard Frog (Lithobates pipiens)
At low temperatures upon emerging from overwintering habitat, a Northern Leopard Frog can appear to be virtually black in colour (Romanchuk and Quinlan 2006).<|control11|><|separator|>
[24]
Effect of background color and low temperature on skin color and ...
Circulating levels of α-melanocyte stimulating hormone (α-MSH) in two species of leopard frog, Rana pipiens and R. chiricahuensis, were measured by ...
[25]
Pigments Cells Respond to Hormones — Biological Strategy
Aug 18, 2016 · Pigments in frog skin change color in response to hormones by moving melanin grains around cells.
[26]
[PDF] A review of colour and pattern polymorphisms in anurans
Forty-six species have been described as undergoing ontogenetic change, and 32 species have been described as sexually dimorphic. That anuran polymorphisms are ...
[27]
Lithobates pipiens - Northern Leopard Frog - NatureServe Explorer
Other Common Names: Grenouille léopard (FR) · Scientific Name Reference: Frost, D.R. · Concept Reference: Frost, D. R. · Name Used in Concept Reference: Rana ...
[28]
Northern Leopard Frog | Mass.gov
Apr 11, 2025 · Northern leopard frog utilizes both aquatic and terrestrial habitat. The primary aquatic habitats are used for overwintering and breeding.
[29]
Northern Leopard Frog (Rana pipiens) | U.S. Fish & Wildlife Service
The northern leopard frog is a slim, smooth-skinned green, brown or yellow-green frog with large dark spots, a white stripe on the upper jaw, and a white belly ...
[30]
Rana pipiens - AmphibiaWeb
Rana pipiens is a slim green or brownish frog, varying in length between about 5 and 11 cm. On its back it has dark rounds spots with pale borders.
[31]
[PDF] Survey of Northern Leopard Frogs (Rana pipiens) at Columbia ...
Seburn et al. (1997) documented leopard frog dispersal movements across wetlands of 1 km, and overland dispersal distances of 0.4 km. These distances should ...
[32]
Rana pipiens - AmphibiaWeb
Rana pipiens Schreber, 1782. Northern Leopard Frog Subgenus: Pantherana, family: Ranidae genus: Rana. Taxonomic Notes: This species was placed in the genus ...<|separator|>
[33]
[PDF] NORTHERN LEOPARD FROG Rana pipiens
Diet and foraging behaviour. The Northern Leopard Frog is an opportunistic forager. Its diet consists of a variety of prey including insects, arachnids ...
[34]
[PDF] Northern Leopard Frog - Lithobates pipiens - Abundance
Formerly Rana pipiens. The Northern Leopard Frog can be found in or near permanent water in the plains, foothills, and montane zones (Smith and Keinath 2007). ...Missing: subspecies | Show results with:subspecies<|control11|><|separator|>
[35]
[PDF] Guide to Managing for Optimal Habitat Attributes: Northern Leopard ...
Field observations of Northern Leopard Frogs suggest that the frogs may prefer feeding, loafing and basking in open and semi-open habitats with short ...
[36]
[PDF] Northern Leopard Frog - Gov.bc.ca
Breeding ponds are warmer and shallower than the streams and ponds used for hibernation, and usually have rich vegetation. Northern Leopard Frogs hibernate from ...Missing: tolerance microhabitat
[37]
[PDF] Northern Leopard Frog - FACT SHEET
The Northern Leopard Frogs were once the largest species of frogs in North America, but they have suffered a large reduction in numbers since the early 1970's.
[38]
Tongue projection mechanisms. (A) Mechanical pulling, as seen in ...
As the genioglossus muscle contracts, the tongue rotates forward. (B) Inertial elongation, as seen in the northern leopard frog, Rana pipiens. Rapid jaw opening ...
[39]
NORTHERN LEOPARD FROG - Waterton Biosphere Region
Summer foraging occurs in moist terrestrial environments near water for escape from predators (e.g., riparian habitats around wetlands or along creeks), but ...<|control11|><|separator|>
[40]
Northern Leopard Frog - Kootenay Conservation Program
Sep 3, 2021 · Northern Leopard Frogs play an important ecological role as both a predator (of insects) and prey (to herons, fish, turtles and more).Missing: trophic | Show results with:trophic<|control11|><|separator|>
[41]
[PDF] Northern Leopard Frog
Fall migrations to the overwintering sites sometimes cover distances of up to 2 miles (Merrell 1970) as evidenced by adult captures far from any suitable ...
[42]
Amphibian - Little Bighorn Battlefield National Monument (U.S. ...
Oct 10, 2025 · Northern Leopard Frog © Eric Teske. Common Name: Northern Leopard ... The male breeding call is a snoring sound lasting two to three ...
[43]
Amphibians - Nebraska Game & Parks Commission
The male's call is a very short trill that lasts only a few seconds. ... Northern leopard frog (Lithobates pipiens). Northern Leopard Frog (Lithobates ...
[44]
[PDF] Conservation of the Northern Leopard Frog (Rana pipiens)
Pace (1974) includes a synonymy of names applied to the leopard frog complex, including Rana pipiens. The name R. pipiens was first applied by Schreber in 1782, ...Missing: binomial | Show results with:binomial
[45]
[PDF] The Northern Leopard Frog - AWS
Activity levels are greatest during the cooler periods of the day, such as dusk and dawn. For a frog, dew-laden grass provides an ideal situation for ...
[46]
Northern Leopard Frog - Lithobates pipiens - California Herps
Family, Ranidae, True Frogs, Rafinesque, 1814 ; Genus, Lithobates, American Water Frogs, Fitzinger, 1843 ; Species, pipiens, Northern Leopard Frog, Schreber, 1782.
[47]
Nature Notes 8/13/2010 - Frogs at our feet - WCLT
Aug 13, 2010 · Leopard frogs can jump up to 20 times their body length. That's 3-6 feet for an adult frog. They leap not only to escape predators, but also to ...Missing: maximum distance
[48]
In vivo muscle force and muscle power during near-maximal frog ...
Mar 10, 2017 · The average jump distance was 59±1cm (> 9 times the frogs' body length) at a take-off angle of 54±1° from the horizontal axis. Table 1 ...<|control11|><|separator|>
[49]
Northern Leopard Frog - B.C. Reptiles & Amphibians
Northern Leopard Frogs hibernate over the winter and are active from April to October in southern Canada, with shorter active seasons at higher latitudes.Missing: period | Show results with:period
[50]
Leopard frog priorities in choosing between prey at different locations
Frogs are able to respond to a prey stimulus throughout their 360° ground-level visual field as well as in the superior visual field.Missing: Northern tadpole lateral line sensory
[51]
[PDF] Population of Northern Leopard Frogs (Rana Pipiens) Migrating ...
Minnesota Northern Leopard Frog populations have two unusual patterns that deviate from the norm of green or brown frogs with uneven lines of dark spots in ...
[52]
[PDF] Northern Leopard Frog (Rana pipiens) Overview
Though Northern leopard frogs can migrate 2-3 kilometers (BISON-M 2009), movements are largely restricted to riparian corridors. This species also exhibits high ...
[53]
interspecific variation in risk response of pond-breeding anurans
Jun 7, 2019 · Camouflage is a primary antipredator response of many frogs (Marchisin & Anderson, 1978), and all three study species exhibited stationary ...
[54]
Frog Skin Innate Immune Defences: Sensing and Surviving Pathogens
Jan 14, 2019 · Peptides with potent cytolytic activity from the skin secretions of the North American leopard frogs, Lithobates blairi and Lithobates ...
[55]
[PDF] Petition to List Western United States DPS of Northern Leopard Frog ...
Jun 5, 2006 · malathion likely make the northern leopard frog more susceptible to predation by a failure to avoid predators and reduce foraging success.
[56]
Assessment in detail - IUCN Red List of Threatened Species
Current population trend · Number of mature individuals · Population severely fragmented · Continuing decline of mature individuals.
[57]
North American Amphibian Monitoring Program - USGS.gov
NAAMP was designed to provide scientifically and statistically defensible, long-term distribution and trend data for calling frog and toad populations.
[58]
Northern Leopard Frog - Province of British Columbia
Mar 18, 2022 · At the Columbia Marshes reintroduction site, over 3,500 hatchling tadpoles were released from both the captive breeding population and wild ...
[59]
[PDF] Northern Leopard Frog (Lithobates pipiens), Western Boreal/Prairie ...
Threats to Northern Leopard Frog Western Boreal/Prairie Populations include drainage and filling of water bodies, conversion of upland habitat, urbanization, ...
[60]
[PDF] Status Report and Assessment of Northern Leopard Frog in the NWT ...
Dec 10, 2013 · Breeding is synchronous and communal, and usually occurs over a few days. Northern Leopard Frogs are not freeze tolerant. They become inactive ...<|separator|>
[61]
[PDF] Pesticide concentrations in frog tissue and wetland habitats in a ...
For example, the herbicide atrazine has the potential to cause immunosuppression in adult northern leopard frogs (Brodkin et al., 2007) and impair sexual.
[62]
A LEAP FORWARD FOR NORTHERN LEOPARD FROGS
Oct 29, 2025 · Before treatment began, 75% (40 of 53) of frogs tested positive for chytrid fungus. After the final treatment on day seven, only 9% (5 of 53) ...Missing: 2020 | Show results with:2020
[63]
Recovery Strategy for the Northern Leopard Frog (Lithobates ...
Feb 24, 2022 · Studies of Leopard Frog movements have recorded maximum distances travelled of 7.9 and 10 km (Dole 1967; Romanchuk and Quinlan 2006).
[64]
[PDF] Northern Leopard Frog Lithobates pipiens - à www.publications.gc.ca
A provincial assessment ranked Northern Leopard. Frogs as medium to high risk with respect to climate change susceptibility, with moderate to poor adaptive.
[65]
Restoration for the Northern Leopard Frog | U.S. Fish & Wildlife ...
Jan 31, 2024 · By targeting adult bullfrogs, ecologists prevented breeding and future population growth, reducing the overall number of animals and egg masses ...Missing: trends | Show results with:trends
[66]
Restoring Leopard Frog Habitat | U.S. Fish & Wildlife Service
The Frog & Fish Restoration Outreach Group (FROG) Conservation Project was an interdisciplinary, multi-organization partnership that sought to restore ...
[67]
Northern Leopard Frog Conservation | The Wilder Institute
Although common across much of their eastern range, the Rocky Mountain population of northern leopard frog is endangered under the federal Species at Risk Act.Missing: trends | Show results with:trends
[68]
https://www.fws.gov/project/restoring-leopard-frog-habitat
[69]
12-Month Finding on a Petition To List the Northern Leopard Frog in ...
Oct 5, 2011 · After review of the best scientific and commercial information, we find that listing the northern leopard frog is not warranted at this time.<|separator|>
[70]
Reintroductions of Northern Leopard Frogs (Lithobates pipiens) in ...
Aug 29, 2024 · PDF | A history of reintroduction efforts for northern leopard frogs (Lithobates pipiens) in western Canada including lessons learned.
[71]
How a Frog Became the First Mainstream Pregnancy Test
May 4, 2017 · In the 1950s, if a woman wanted to know if she was pregnant, she needed to get her urine injected into a frog.
[72]
Effects of two pesticides on northern leopard frog (Lithobates pipiens ...
Mar 27, 2021 · Herein, we investigate the effects of long-term exposure to two individual neonicotinoids (clothianidin or thiamethoxam) at either low or high ...Missing: toxicology | Show results with:toxicology
[73]
Immunosuppression in the northern leopard frog (Rana pipiens ...
Amphibian immune defenses involve both innate defense mechanisms (i.e., those present before the pathogen is introduced) and adaptive components that ...Missing: Lithobates | Show results with:Lithobates
[74]
Effects of ultraviolet light and methoprene on survival and ...
Oct 26, 2009 · The objective of this study was to assess two stressors hypothesized as responsible for limb malformations in amphibians: methoprene, an insect ...
[75]
Proximity to Pollution Sources and Risk of Amphibian Limb ...
Together, these studies have shown that exposure to field-collected water and sediment can result in limb abnormalities and that a number of chemicals can have ...
[76]
Onconase and Amphinase, the Antitumor Ribonucleases from Rana ...
The cytostatic effects of Onconase and Amphinase are manifested as cell arrest in the G1 cell cycle phase. Apoptosis then follows involving activation of ...Missing: Northern | Show results with:Northern
[77]
Cancer chemotherapy – ribonucleases to the rescue - ScienceDirect
Onconase®, from the Northern leopard frog, is currently in clinical trials as a cancer chemotherapeutic. Recent research has revealed some key factors ...
[78]
Sepulveda Receives AgSeed Grant for Northern Leopard Frog ...
Feb 22, 2022 · The Northern leopard frog is a common species used in the study of endocrine disruption, cancer and drug discovery, conservation biology and ...Missing: rapid | Show results with:rapid
[79]
A review of the scientific literature for evidence of amphibian sentience
We found that amphibians were assumed to be capable of the following emotions and states; stress, pain, distress, suffering, fear, anxiety, excitement, ...
[80]
Atrazine-induced hermaphroditism at 0.1 ppb in American leopard ...
We showed that atrazine exposure (> or = to 0.1 ppb) resulted in retarded gonadal development (gonadal dysgenesis) and testicular oogenesis (hermaphroditism) ...
[81]
Pesticide atrazine can turn male frogs into females - Berkeley News
Mar 1, 2010 · Recent studies also found a possible link between human birth defects and low birth weight and atrazine exposure in the womb. As a result of ...Missing: Northern | Show results with:Northern
[82]
Three auditory brainstem response (ABR) methods tested and ...
Jan 19, 2021 · We used three different methods in the same individual frogs: stimulating with brief tone bursts (tABR), long-duration tones (ltABR) and masked ...<|separator|>
[83]
Temporal processing in the dorsal medullary nucleus of the ...
1. Single-unit responses to different temporal acoustic parameters were characterized in the dorsal medullary nucleus (DMN) of the Northern leopard frog, ...
[84]
Neural correlates of frog calling: production by two semi ...
The anterior preoptic nuclei of the isolated brainstem of male, Northern leopard frogs (Rana p. pipiens) were stimulated electrically and neural correlates ...
[85]
Hormone cross-regulation in the tadpole brain: Developmental ...
We examined changes in thyroid hormone receptors (TRα and TRβ) and the estrogen receptor (ERα) in the brain of Rana pipiens throughout metamorphosis.
[86]
Influence of thyroid hormones on neuronal death and differentiation ...
The present experiments demonstrate that thyroid hormone mediates neuronal death as well as differentiation. Hypophysectomized Rana pipiens larvae exposed ...
[87]
Developmental Profiles and Thyroid Hormone Regulation of Brain ...
Dec 6, 2011 · Previously, we demonstrated that THs affect sex steroid-related gene expression in the developing brain of Silurana tropicalis and Rana pipiens; ...
[88]
Detection of stationary objects by frogs (Rana pipiens) after ablation ...
Frogs with tectum removed bilaterally were unable to make any overt response to either moving prey objects or threatening stimuli.
[89]
Responses from Single Auditory Units in the Eighth Nerve of the ...
Auditory units in the eighth nerve of the leopard frog (Rana pipiens) are frequency selective with best frequencies from less than 100 Hz to near. 2000 Hz.
[90]
Auditory input to a vocal nucleus in the frog Rana pipiens - PubMed
Most of these neurons had V-shaped tuning curves, with best excitatory frequencies between 200-1400 Hz, thresholds between 31-87 dB SPL, latencies between 10-50 ...Missing: 500-2000 | Show results with:500-2000
[91]
Influence of dopamine D2-type receptors on motor behaviors in the ...
In particular, D1 receptor-specific optogenetic stimulation increases ... pipiens, formerly known as Rana pipiens) [20]. These motor effects are also ...
[92]
Sound-by-sound thalamic stimulation modulates midbrain auditory ...
This study tested whether electrical stimulation of the thalamus modulates auditory excitability and relative binaural sensitivity in neurons of the amphibian ...
[93]
(PDF) Hindlimb muscle fiber types in two frogs (Rana catesbeiana ...
Aug 6, 2025 · Here, T1 and T2 values were determined in pure slow-twitch and fast-twitch rabbit muscles and in rabbit muscles with mixed fiber types. The ...
[94]
Sarcomeric Ca2+ gradients during activation of frog skeletal muscle ...
We have been able to resolve steep intra-sarcomeric gradients of Ca 2+ -related fluorescence during activation of frog skeletal muscle.Missing: Northern leopard
[95]
The evolution of human fatigue resistance | Journal of Comparative ...
May 12, 2022 · speed trade-off in frog muscle suggests that a physiological conflict between maximum power output and fatigue resistance exists at the level ...
[96]
Sliding filament theory - Wikipedia
The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement.
[97]
Design and Dynamic Model of a Frog-inspired Swimming Robot ...
Aug 4, 2017 · A frog-inspired robot is designed to mimic the frog swimming based on its three DOFs in the leg and the pneumatic muscles serving as the joint ...