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Cuban gar
Cuban gar
Cuban gar
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Cuban gar
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Clade: Ginglymodi
Order: Lepisosteiformes
Family: Lepisosteidae
Genus: Atractosteus
Species:
A. tristoechus
Binomial name
Atractosteus tristoechus
Bloch & Schneider 1801
Synonyms[2][3]
  • Esox tristoechus Bloch & Schneider 1801
  • Lepisosteus tristoechus (Bloch & Schneider 1801)
  • Lepidosteus manjuari Poey 1853
Wikimedia Commons has media related to Atractosteus tristoechus.

The Cuban gar (Atractosteus tristoechus), also known as the manjuarí, is a fish in the family Lepisosteidae.[4] It is a tropical, freshwater species, although it also inhabits brackish water.[5] It is found in rivers and lakes of western Cuba and the Isla de la Juventud.[5] The flesh of the fish is edible, but the eggs are poisonous for humans.[6]

Cuban gar spawn seasonally in the floodplains of large rivers.[7]

Behavior

[edit]

Cuban gar typically hunt alone and avoid other members of their species. The exception to this is during spawning season, when larger parties of around 20 gar form to hunt. Sometimes, the groups break up into smaller groups, and two to eight males accompany a female. Atractosteus gar species generally have sex ratios skewed towards males (in the cases of tropical gar or alligator gar), although research has yet to show this trend in the Cuban gar.[8][9][10]

Morphology

[edit]

Adult Cuban gars are typically around 1 m (3.3 ft) in length, but can grow as large as 2 m (6.6 ft). There is no known variance in length relative to sex. This places it as the second largest extant species of gar, after the alligator gar.[7]

The Cuban gar, along with other species of gar, is also notable for its high tolerance of high ammonia and nitrate levels in water,[11] its ability to breathe some atmospheric air in absence of sufficiently oxygenated water,[12] and its disease resistance.[13]

Larval development

[edit]

After hatching, Cuban gar larvae undergo three stages of organogenesis and development: attached (days 1–3), transitional (days 4–10), and free-swimming (days 11–18).[14] During the attached stage, the larvae develop rudimentary intestines, stomachs, pancreases, and esophagi that help the larvae transition from feeding off the egg yolk to normal feeding, which begins during the transitional phase. The transitional phase is marked by further development of these organs and a lack of obvious yolk.

During this phase, teeth also develop. Once separation occurs between the stomach and intestines—increased organ size and complexity, and completely exotrophic behavior has arisen—the larvae are considered "free swimming".[14] While they are larvae, Cuban gar grow from around 1.5 cm (0.6 in) in length in the attached phase, to 4 cm (1.6 in) in length in the free-swimming phase.[citation needed]

Ecology

[edit]

Like other species of gars, Cuban gar are top-level predators in freshwater ecosystems.[15] Adults feed on freshwater fishes and birds. Young are prey to the introduced largemouth bass (Micropterus salmoides). As an animal with a high trophic level, the gar has lost much of its population due to overfishing and habitat loss. Attempts to restore natural fish populations using them in aquaculture are currently in progress,[15] but these ideas have yet to reach implementation.

Cuban gar are currently under research for use in broodstocking, both due to the threatened status of gar species and due to the potentially valuable role of gar in reducing the pressure of fisheries on natural aquatic ecosystems.[16] No implementation of Cuban gar broodstocking for ecological protection has yet occurred, however.

References

[edit]
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Cuban gar

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from Grokipedia
The Cuban gar (Atractosteus tristoechus) is a primitive ray-finned belonging to the family Lepisosteidae, characterized by its elongated, cylindrical body covered in hard, diamond-shaped ganoid scales, a long beak-like snout lined with sharp teeth, and a vascularized that enables facultative air breathing. Reaching a maximum total length of up to 200 cm and weighing several kilograms, it exhibits a predatory lifestyle as an ambush hunter, primarily feeding on smaller and crustaceans, with adults occasionally preying on birds. Known locally as manjuarí, this species is a "" with an evolutionary lineage tracing back approximately 240 million years, having endured five mass extinction events. Endemic to western and the nearby , the Cuban inhabits a range of slow-moving freshwater environments, including large rivers, lakes, swamps, floodplains, backwaters, and sluggish tributaries, while tolerating brackish conditions but avoiding swift currents. Its distribution is highly restricted, primarily within the Ciénaga de Zapata wetland system and associated coastal basins, making it one of the most range-limited members of the order . Juveniles are particularly vulnerable to predation by such as ( salmoides), while adults thrive in warm waters typically ranging from 18–23°C. Biologically, the Cuban gar is oviparous, with beginning around 3–4 years for males and later for females, though specific details on spawning habits remain limited; its is for humans, but the eggs are poisonous. In captivity, it can live for up to 25 years and has been subject to breeding programs due to its unsuitability for home aquaria given its size and longevity. Classified as critically endangered on the IUCN Red List since 2020, the species has experienced an over 80% population decline since the late 1990s, driven by habitat degradation from drainage and pollution, overfishing, and invasive predators like the African walking catfish (Clarias gariepinus), introduced in 1999. Conservation efforts include a ban on capture and trade since 1996, ongoing captive breeding at Cuba's National Aquarium, and habitat protection initiatives, though challenges persist due to its small, fragmented range.

Taxonomy

Classification

The Cuban gar, Atractosteus tristoechus, is classified within the kingdom Animalia, phylum Chordata, class , order , family Lepisosteidae, genus , and species A. tristoechus. This placement situates it among the seven extant species worldwide, all of which belong to the family Lepisosteidae, known for their primitive ray-finned fish characteristics. As the sole gar species endemic to the region, specifically restricted to western and the , the Cuban gar is distinct from its North American congeners, such as the (A. spatula), which inhabits freshwater systems across the central and . This highlights its isolated evolutionary trajectory within the Atractosteus, contrasting with the broader distribution of other gars in continental North and . Gars, including the Cuban gar, represent "living fossils" with a lineage originating in the period approximately 150 million years ago, characterized by minimal morphological change over time. This ancient group has endured multiple mass s, notably surviving the Cretaceous-Paleogene 66 million years ago that eradicated non-avian dinosaurs, as evidenced by gars appearing shortly after the Chicxulub impact.

Nomenclature

The binomial name of the Cuban gar is Atractosteus tristoechus (Bloch & Schneider, 1801). This species was first described in 1801 by German naturalists and Johann Gottlob Theodor Schneider in their work Systema Ichthyologiae, based on specimens from . Several synonyms have been used historically for this species, including tristoechus Bloch & Schneider, 1801 (the original combination), tristoechus (a later reassignment to the genus Lepisosteus), and Lepidosteus manjuari Poey, 1853 (proposed by Cuban ichthyologist Felipe Poey). In English, it is commonly known as the Cuban gar, while in Spanish and particularly in Cuba, it is called manjuarí, a name derived from the Taíno indigenous language and referring to its elongated, spear-like snout. The genus name Atractosteus originates from Greek átraktos (spindle) and osteon (bone), alluding to the species' cylindrical body armored with heavy, bone-like ganoid scales; the specific epithet tristoechus derives from Latin tri- (three) and Greek stoîkhos (row), describing the three rows of teeth on the lower jaw. The genus Atractosteus is shared with other tropical gar species, such as the alligator gar (A. spatula).

Description

Morphology

The Cuban gar (Atractosteus tristoechus) possesses an elongated, robust, and cylindrical body covered in hard, rhomboidal ganoid scales that are diagonally interlocked via a peg-and-socket structure, providing robust armor against predators. These scales number 56–62 along the and 49–51 anterior to the , contributing to the fish's rigid, arrow-like form adapted for ambush predation. The body reaches a maximum length of 2 m, with a slightly asymmetrical, fan-shaped caudal fin. The head features a long, beak-like snout that is broad and relatively short, comprising less than 60% of the head length, equipped with large fangs arranged in two rows on both jaws and a single additional row along the side of the palatal roof for grasping slippery prey such as . The dorsal and anal fins are positioned posteriorly near the , enhancing stability and during rapid strikes, while the top of the bears small, round bony tubercles. Key physiological adaptations include a highly vascularized that functions as a supplementary , enabling facultative air-breathing to tolerate low-oxygen environments common in its native wetlands. Sensory structures support prey detection in turbid conditions, including a well-developed system along the scaled body for sensing water movements and vibrations from nearby organisms. Additionally, like other members of the family Lepisosteidae, the Cuban gar possesses electroreceptive ampullae derived from the placodes, which detect weak bioelectric fields emitted by hidden prey in murky waters. The Cuban gar is dark brown above with a whitish belly. Compared to the more robust (Atractosteus spatula), the Cuban gar has a slightly more slender build and a broader, shorter , with only a single row of palatal teeth rather than the dual rows typical of the former.

Size and growth

The Cuban gar typically reaches an adult length of 100 cm total length (), though individuals can grow to a maximum recorded length of 200 cm . Juveniles exhibit rapid growth that slows upon reaching maturity; larval stages achieve daily length increases of 1.30–1.75 mm at s of 26–30 °C, with the highest rates observed at 26 °C. Growth is influenced by environmental factors including , , and food availability, which affect both rate and overall size attainment. The species has a lifespan of several decades. is minimal, with no known significant differences in length relative to sex.

Distribution and habitat

Geographic range

The Cuban gar ( tristoechus) is endemic to , occurring naturally only within the western portion of the island and the nearby . Its distribution is confined to freshwater rivers, lakes, and associated wetlands in the provinces of , , Mayabeque, and , primarily the Ciénaga de Zapata swamp and associated coastal basins. Historically, the was more widespread across various freshwater habitats in prior to the 20th century, but its range has since become severely fragmented due to habitat alterations, resulting in a highly restricted current distribution. No natural occurrences of the Cuban exist outside of . No introduced populations of the Cuban have been confirmed beyond its native range, though the is occasionally traded in the international aquarium market, which presents potential risks for unintentional releases into non-native ecosystems.

Environmental preferences

The Cuban gar (Atractosteus tristoechus) primarily inhabits slow-moving freshwater and low-salinity bodies, including s, lakes, swamps, and estuaries. It shows a clear for larger and swamp systems featuring extensive floodplains and sluggish tributaries, while avoiding fast-flowing streams. These habitats provide dim and low water flow, ideal for its predatory lifestyle among vegetated areas. This species thrives in warm tropical water conditions, with temperatures typically ranging from 18°C to 23°C; larval hatching and growth are optimized at 26–28°C, where survival exceeds 90% and development proceeds efficiently. It tolerates low dissolved oxygen levels through facultative air-breathing, utilizing a highly vascularized to supplement respiration in hypoxic environments. Salinity tolerance extends from freshwater to brackish conditions, an linked to its ancient lineage. The Cuban gar exhibits tolerance to seasonal flooding in floodplain-dominated systems.

Behavior

Feeding habits

The Cuban gar (Atractosteus tristoechus) is an opportunistic carnivore that primarily preys on smaller freshwater fishes and aquatic crustaceans, with occasional records of bird consumption. In its native Cuban freshwater systems, it targets a variety of fish species, including introduced tilapia (Oreochromis spp.) and native cyprinodontiforms such as pupfishes, reflecting its adaptability to local prey availability. Crustaceans form a significant portion of the diet, particularly in vegetated shallows where these prey are abundant. As an , the Cuban employs a sit-and-wait strategy, often positioning itself motionless among aquatic vegetation or submerged structures to surprise passing prey. It forages solitarily, using its elongated, toothed to deliver rapid strikes that slash or impale victims, a method facilitated by the ' robust cranial morphology. This solitary occurs predominantly in rivers, lakes, and associated vegetated habitats, where the gar's cryptic body pattern aids concealment. Ontogenetic shifts in diet are evident, with juveniles initially relying on small invertebrates such as microcrustaceans and zooplankton, transitioning to larger fish as they grow and their predatory capabilities develop. Adults, reaching lengths over 1.5 m, consume bigger prey items, including fish up to substantial sizes relative to their body. As a top predator in Cuban freshwater ecosystems, the Cuban gar exerts regulatory pressure on prey populations, helping to control numbers of smaller fish and maintaining trophic balance. This role underscores its ecological importance, though habitat alterations may disrupt these dynamics.

Social interactions

The Cuban gar (Atractosteus tristoechus) exhibits a predominantly solitary lifestyle, typically hunting and residing alone while avoiding interactions with conspecifics outside of reproductive periods. This aligns with observations in closely related , where individuals maintain high site fidelity and limit movement, suggesting minimal social grouping in non-breeding contexts. During spawning migrations, loose aggregations of more than 20 individuals may form temporarily, often splitting into smaller units consisting of temporary male-female pairs, with 2–8 males accompanying a single female for purposes. Information on ratios in wild populations is limited due to the species' critically endangered status and restricted range; while some species show male-biased ratios, trends for the Cuban gar remain unclear, potentially skewed toward females in remnant populations based on preliminary surveys.

Reproduction

Spawning

The spawning of the Cuban gar ( tristoechus) occurs during the rainy season, when rising water levels flood shallow areas, providing suitable conditions for . This environmental trigger prompts adults to migrate into inundated lowlands and vegetated shallows along river floodplains, where water temperatures typically range between 25–30°C. Courtship involves multiple males participating in of eggs. Groups of up to 20 individuals may form during this period, marking a temporary shift from the species' typical solitary behavior. Spawning takes place in shallow, vegetated waters where adhesive eggs are broadcast over submerged aquatic plants and debris. These eggs contain ichthyotoxins, rendering them poisonous to humans and other animals if ingested, though they pose no threat to the or most aquatic predators. Males reach around 3–4 years of age, with females maturing later.

Larval development

The eggs of the Cuban (Atractosteus tristoechus) hatch in approximately 100 hours (about 4-5 days) at 28°C, producing larvae with an initial total length of roughly 1.3 cm that retain a substantial for endogenous nutrition. Newly hatched larvae enter an attached phase lasting 0-4 days after (DAH), during which they adhere vertically to substrates like using a specialized on their heads, minimizing energy expenditure while the provides nourishment. This phase transitions into a more active period from 4-10 DAH, marked by the development of pectoral and pelvic fins, the onset of limited , and the gradual depletion of the between 8-13 DAH, prompting a shift to partial exogenous feeding around 7-11 DAH. By 10 DAH, larvae become fully free-swimming, initiating predatory feeding behaviors as they pursue small prey items in the . Throughout these early stages, growth proceeds at an average rate of 1.30 mm per day at 28°C, enabling larvae to reach approximately 4 cm in total length by 18 DAH, representing a threefold increase from hatching size. However, this period is characterized by variable mortality in controlled settings, reaching up to 30% at higher temperatures like 30°C, and likely higher in the wild due to predation pressures. occurs as larvae surpass 4-5 cm, with the loss of larval traits such as the cement gland and any remaining remnants, resulting in juveniles that closely resemble scaled-down adults in form and function. These early juveniles remain vulnerable to predation by larger , contributing to their role in the aquatic .

Ecology and conservation

Trophic role

The Cuban gar ( tristoechus) occupies the role of an in the freshwater ecosystems of western , primarily feeding on and crustaceans, which helps regulate prey populations and maintain ecological balance. As a piscivorous , it exerts top-down control on lower trophic levels, preying on both native and potentially overabundant , thereby contributing to the stability of food webs. Occasionally, adults also consume birds, adding complexity to its predatory interactions within the aquatic-terrestrial interface. Juveniles face predation from introduced (Micropterus salmoides) and avian species, positioning young Cuban gar lower in the , while adults, reaching lengths over 2 meters, have few natural predators due to their size and armored bodies. This ontogenetic shift underscores the species' vulnerability during early life stages, which influences overall . The Cuban gar competes with other piscivores, notably the invasive African (Clarias gariepinus), for shared resources; the catfish's rapid proliferation has displaced native predators like the by outcompeting them and preying on their eggs, exacerbating declines in Cuban gar populations. In wetland ecosystems, the Cuban gar provides key services by promoting through predation on overabundant prey, preventing dominance by any single and supporting diverse assemblages. Its sensitivity to habitat degradation and severe —such as from agricultural runoff and deterioration—further positions it as an indicator of in Cuba's freshwater systems, where population declines signal broader stress.

Threats and status

The Cuban gar (Atractosteus tristoechus) is classified as Critically Endangered on the since 2020, upgraded from its previous Endangered status, due to an inferred exceeding 80% over the past three generations (approximately 30 years). This assessment is based on criteria A2ce, reflecting continuing decline driven by habitat degradation, exploitation, and impacts. Primary threats include extensive habitat loss from and dam construction, which have fragmented and degraded the species' endemic freshwater swamp habitats in western . for both subsistence and sport purposes has further depleted populations, as the Cuban gar is valued for its size and edibility (though its eggs are toxic). Additionally, such as the African (Clarias gariepinus), introduced in the late 1990s, pose a severe risk by outcompeting juvenile Cuban gar for resources and prey in shared wetlands. Current population estimates indicate fewer than 10,000 mature individuals remain, severely fragmented across 5-6 isolated localities, primarily within the Ciénaga de Zapata National Park and remnant swamps on the Isle of Youth. Densities have plummeted from 150-200 individuals per linear kilometer in the prior to 1999 to just 1-5 per kilometer in recent surveys. This decline traces back to the , when habitat alterations from development and the introduction of non-native began accelerating losses in the species' narrow endemic range.

References

  1. https://www.fishbase.se/summary/Atractosteus-tristoechus.html
  2. https://www.seriouslyfish.com/species/atractosteus-tristoechus/
  3. https://www.discovermagazine.com/the-cuban-gar-survived-dinosaurs-and-5-mass-extinctions-but-can-it-survive-46348
  4. https://www.iucnredlist.org/species/46104013/124286091
  5. https://www.biolib.cz/en/taxon/id139587/
  6. https://animalia.bio/cuban-gar?taxonomy=8141
  7. https://www.fws.gov/species/cuban-gar-atractosteus-tristoechus
  8. https://biogeodb.stri.si.edu/caribbean/en/thefishes/species/2764
  9. https://www.iflscience.com/what-is-a-living-fossil-first-evidence-of-a-biological-mechanism-reveals-all-73272
  10. https://www.sci.news/paleontology/atractosteus-grandei-11103.html
  11. https://pmc.ncbi.nlm.nih.gov/articles/PMC9198771/
  12. https://etyfish.org/lepisosteidae/
  13. https://www.marinespecies.org/aphia.php?p=taxdetails&id=405353
  14. https://www.fishbase.se/Nomenclature/SynonymSummary.php?ID=121669&GenusName=Atractoseus&SpeciesName=tristoechus
  15. http://tainacubaplusmagazine.com/pdf/cubaplus-magazine-vol03.pdf
  16. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=86528
  17. https://pmc.ncbi.nlm.nih.gov/articles/PMC5354974/
  18. https://a-z-animals.com/blog/gar-teeth/
  19. https://www.monsterfishkeepers.com/forums/threads/different-gar.723037/
  20. https://www.scielo.org.mx/pdf/era/v1n1/v1n1a3.pdf
  21. https://www.researchgate.net/publication/49638637_Ontogenetic_Changes_in_the_Morphology_and_Morphometry_of_Cuban_Gar_Atractosteus_tristoechus
  22. https://animalia.bio/cuban-gar
  23. http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S2007-90282014000100003
  24. https://www.researchgate.net/publication/225268646_Digestive_enzyme_activity_during_early_larval_development_of_the_Cuban_gar_Atractosteus_tristoechus
  25. https://www.researchgate.net/publication/353397249_A_Living_Treasure_on_the_Brink_of_Extinction_Conservation_Status_of_the_Cuban_Gar_Atractosteus_tristoechus_Bloch_Schneider_1801
  26. https://link.springer.com/article/10.1007/s10641-023-01491-1
  27. https://dialnet.unirioja.es/descarga/articulo/6121125.pdf
  28. https://www.researchgate.net/publication/260215079_Embryonic_Development_of_Cuban_Gar_Atractosteus_tristoechus_Under_Laboratory_Conditions
  29. https://www.redalyc.org/pdf/3586/358633237003.pdf
  30. https://pubmed.ncbi.nlm.nih.gov/21110719/
  31. https://www.wlrn.org/show/latin-america-report/2019-06-03/cuba-hopes-a-catfish-will-solve-its-food-crisis-but-is-it-wrecking-the-islands-ecosystem
  32. https://www.researchgate.net/publication/23765447_Implications_of_Clarias_Gariepinus_African_Catfish_propagation_in_cuban_waters
  33. https://doi.org/10.2305/IUCN.UK.2021-1.RLTS.T46104013A124286091.en
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