Paleosuchus palpebrosus

Geographic Range

Paleosuchus palpebrosus , Cuvier's dwarf caiman, is most commonly found in the wetlands of Brazil, French Guiana, Surinam, Guyana, and Venezuela. Widespread throughout the Orinoco and Amazon basins, P. palpebrosus inhabit areas extending from Colombia, Venezuela, and the Guianas south to Sao Paulo and the upper Rio Paraguay in southern Brazil and west to the Rio Pastaza in Ecuador.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

This species can be found near rivers and inundated savanna areas including the Orinoco and Amazon rivers, as well as those in eastern Paraguay. This species prefers clean, clear, fast-moving streams or rivers in forested areas containing waterfalls and rapids. Paleosuchus palpebrosus mostly inhabit fordable freshwater, avoiding salty, briny waters. It likes cooler waters compared to other caimans. Across inhabited areas, P. palpebrosus has been known to occupy streams of varying sizes, where they are spotted resting near the shorelines. This species is also terrestrial, and has been seen relaxing on piles of small rocks and residing near decaying trees. Likewise, P. palpebrosus is known to dwell in burrows, which are up to 1.5-3.5 meters long. Populations in southern Brazil and Venezuela are limited to waters with very low nutrients. P. palpebrosus can be found resting on rocks, or in shallow water with its back exposed on the surface and its head facing the sun. Preferring colder temperatures, they can survive in cool conditions (as low as 6 degrees Celsius).

• Habitat Regions
• tropical tropical
• terrestrial terrestrial
• freshwater freshwater

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• marsh marsh
• swamp swamp

• Other Habitat Features
• riparian riparian

Physical Description

This species is the smallest of the alligator family. Males grow to about 1.3-1.5 meters, while the females grow to 1.2 meters. They can reach a mass of about 6-7 kg.

Paleosuchus palpebrosus retain a reddish-brown body color. The dorsal surface is mostly plain and nearly black, while the upper and bottom jaws are covered with several dark and light spots. The tail is marked with encircling bands to the tip. Most of these caimans have brown eyes, but some have also been known to have gold-yellow eyes. P. palpebrosus do not have the same dental formula as other caimans. Most caimans have 5 premaxillary teeth in the upper jaw, but this species only has 4. Scale characteristics allow the differentiations between all other species. P. palpebrosus has 17-20 longitudinal rows on their dorsal and its tail (double crest) has bands of 7-9 rows. Paleosuchus palpebrosus has more osteoderms (bony plates) covering its skin than any other species.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Development

When hatched, the young have almost the identical features as an adult. The sex of hatchlings is determined by the incubation temperature of the eggs. Differences in size can be used to differentiate the sexes. Growth continues throughout their lifespan. The fastest rate of growth occurs during the first 2 years, then declines with age thereafter. For the first 5 years, P. palpebrosus grow at a rate of 6-8 cm per year. It takes approximately 10 years to for one of these caimans to complete maturity and develop full adult characteristics.

• Development - Life Cycle
• temperature sex determination

Reproduction

Courtship and copulation take place at the end of the dry season. At this time, the males, are seen to lift their heads high and hold their tails almost vertically out of the water. The males release what is described to be a "roar"-like sound. The description of the "roaring" varies, and it commonly heard as simply a grunt-like call. The varying sounds and noises indicate the actual complexity of mating rituals within this species. The male, which mates with multiple females, performs distinctive mating displays, then approaches any receptive female. Rather than during the day, P. palpebrosus prefer to mate during the night. Normally in shallow waters, copulation takes place with the female mounting the male and twisting her tail under his. The actual mating process can last anywhere between 5-10 minutes or even up to a whole day. It can also occur repeatedly over several days, after which both male and female settle in the water for a period. Most females are only able to breed once a year, but on the other hand, if bred in captivity and fed efficiently, the females are able to breed 2 or 3 times a year.

• Mating System
• polygynous polygynous

This species is reported to nest during the dry season, during the wet season, or all year round, depending on the locality. More specifically, studies show P. palpebrosus prefer to nest at the end of the dry season and the beginning of the rainy season in areas with warm climates. When ready to start nesting, the females stop feeding and begin the mating process. The females can lay around 10-25 eggs. Both female and male P. palpebrosus build nests for their eggs. These nests are made of soil, usually mud, blended with fresh and rotten leaves, small branches, and other vegetation. Like other caimans, this species is a mound-nester where the females lay their eggs and bury them underneath the mound. These nests are generally small in diameter and height. These eggs are white, long, and weigh anywhere from 61-70 grams. The eggs hatch after 90 days. The female opens the nest in response to vocalizations of the young from within the nests. After the young hatch from their eggs, they continue to stay beneath the debris of the nest for several days, staying away from the water. It is said that the adults open the nest and direct their young toward the water, but studies do show the lack of parental care. The general behavior of adult males are to leave once after the female lays her eggs. Males do not regularly stay near the females during the hatching or post-hatching period. Sexual maturity is dependent on size, and relates to age as it correlates with growth. When a male reaches a size of 1.1 meters, it has become sexually mature and the females are ready to breed when they are about 1 meter in length. For P. palpebrosus to become completely sexually mature, it could take more than 10 years.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

The degree of parental care after hatching varies with local conditions. The nest is made by both parents. Studies show that the females remain with the hatchling group for only a few weeks before the hatchlings disperse. Then, the young are left alone and the mother leaves. The female rarely returns to her nesting site to search for her young, but can recognize them by smell. The nesting period is very dangerous for the young. Many predators lurk around nests to snatch eggs for food. In response, the female and male parents become defensive and take whatever action is necessary to guard their eggs. The female is always alert and remains near the nest during this period and will react to the slightest movement. Males do not regularly stay near the female during the hatching or post-hatching period. Furthermore, captive caimans are much more aggressive during their nesting period. The female can become very hostile and charge from the water at any sudden movement near the nest. She remains by the eggs for long periods, even without an apparent threat. Other defensive behaviors are tail slapping and splashing water by snapping their jaws. Sometimes, P. palpebrosus hatchlings are found alone or in pairs without any parental protection at all.

• Parental Investment
• pre-fertilization
  • provisioning
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

The crocodilians are known to have long lifespans. Although P. palpebrosus adults are long lived, the exact longevity is not known. Generally, the adults have been known to live for 20-40 or more years. In captivity this species has a better longevity than of wild individuals.

Behavior

Paleosuchus palpebrosus is a social species with diverse and interesting behaviors. Like most crocodilians, they can convey social messages through sounds, postures, movements, smells, and touch. Although most crocodilians are somewhat social, P. palpebrosus are typically found alone or in pairs. When in pairs or small groups, P. palpebrosus are known to migrate long distances due to competition. Systematic studies of adults indicate that there are dominance hierarchies within groups. The most hostile and aggressive individuals appear to be the most dominant. These individuals control access to mates, nest sites, food, and living space. Dominance is asserted and maintained by social signals and displays. Challenges within a group may occur, but physical combat is rare. When threatened, this species may inflate its body to exaggerate size and begin to hiss defensively. Oftentimes, when an individual's status is challenged, they will compete with each other by holding their bodies in a vertical position above the water's surface, displaying their size to discourage their opponent from more aggression.

• Key Behaviors
• terricolous
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• nomadic nomadic
• daily torpor
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

Dominant males defend territories from which they exclude other males. The defended resources include access to mates, nesting sites, and foraging areas. Territories may be defended all year round and vary in size with seasonal changes.

Communication and Perception

Communication begins in the egg and continues throughout their entire life. Sound, postures, motions, and touching are few of the many methods of communication in this species. Along with vocal signals, Paleosuchus palpebrosus communicate via nonverbal sounds, performing actions such as head-slapping or jaw-clapping at the water's surface. Like most caimans, P. palpebrosus males emit a grunt-like "chumph" sound by expelling air through the nostrils during courtship. When in water, exposure of the head, back, and tail above the surface conveys important information about an individual's social status and intent.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

P. palpebrosus is a nocturnal hunter, preferring to spend the daylight hours basking. The young feed on aquatic and shoreline insects of many species. Their food includes tadpoles, frogs, snails, crabs, shrimp, and small fish. Adults mainly consume tadpoles, frogs, snails, fish, small mammals, and a wide variety of insects. Diet changes with the size and age of this species. As an adult, there is an increase in the fish intake as well as a greater intake of small crabs, birds, reptiles, and small mammals. Like other crocodilians, P. palpebrosus experiment with their food, so they will capture whatever prey is available. Prey is usually swallowed whole or in large pieces. The stomach enzymes in crocodiles and alligators are so strong that pH levels are among the lowest ever recorded in any vertebrate. Another characteristic of P. palpebrosus is the amount of gastroliths (small stones) inside the stomach. The stones are found only in one chamber of the stomach, the gizzard, and this one chamber has walls with folds to permit expansion and contraction. It is said these gastroliths help in the process of digestion, the stones churn inside the stomach, breaking apart the food.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore
  • insectivore insectivore

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• fish
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms
• aquatic crustaceans

Predation

The most dangerous time in a caiman's life is while it is still in the egg. Without protection, predators such as rats, procyonids , and other carnivores can hastily clean a nest of eggs. If the eggs hatch, the young are still at a high risk of predation. The young are taken primarily by wading birds , snakes , and a host of other carnivorous animals. Due to the large number of bony osteoderms underneath the scales, many predators are not able to swallow this species. The only predators of adult P. palpebrosus are large boas , green anacondas , and jaguars .

Ecosystem Roles

Cuvier's dwarf caiman is considered a "keystone species" that maintains ecosystem structure and function by selective predation on fish species (such as piranhas ) that if left unchecked, would transform the ecosystem. Although P. palpebrosus is small in size, it is known to have fewer predators than related species because of its uniquely armored and jagged skin.

• Ecosystem Impact
• keystone species keystone species

Economic Importance for Humans: Positive

Although the meat of P. palpebrosus is indeed very palatable, these small animals do not produce enough to be considered beneficial. The skin is also traded to a degree. However, alternatives are usually favored over the small and extremely tough hide of this dwarf caiman. Also hunting Cuvier's dwarf caiman is difficult due to their reclusive, solitary nature and their preference for densely forested habitat.

Small crocodilians such as Paleosuchus palpebrosus and Paleosuchus trigonatus are currently popular in the pet trade due to their relatively small and theoretically manageable size.

• Positive Impacts
• pet trade pet trade
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

This species has no negative economic affect on humans.

As pets, P. palpebrosus are notoriously hostile and cannot be handled comfortably. Bites from adults are exceedingly painful.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

Right now, P. palpebrosus is not considered in need of active conservation. The IUCN rates at as Lower Risk, and of Least Concern. However the species is listed in Appendix II of CITES, which regulates international trade in the animals or their parts. The recent removal of larger, dominant crocodilian species (e.g. Caiman crocodylus ) may have allowed smaller species like P. palpebrosus to expand into habitats from which it formerly was excluded.

Other Comments

This species, P. palpebrosus , was first described by the Baron Cuvier in 1807 from Cayenne, French Guiana.

Additional Links

Encyclopedia of Life

Contributors

David Armitage (editor), Animal Diversity Web.

Heiry Choi (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

References

Grenard, S. 1991. Handbook of Alligators and Crocodiles . Malabar, Florida: Krieger Publishing Company.

Guggisberg, C. 1972. Crocodiles: Their Natural History, Folklore, and Conservation . Great Britain: David & Charles Limited.

Halliday, T., K. Adler. 2002. The New Encyclopedia of Reptiles and Amphibians . Oxford: Oxford University Press.

Platt, S., T. Rainwater, S. McMurry. 2002. Diet, gastrolith acquisition and initiation of feeding among hatchling Morelet's crocodiles in Belize. Herpetological Journal , 12/2: 81-84.

Santos, S., G. Mourao. 1996. Diets of Caiman crocodilus yacare from different habitats in the Brazilian Pantanal. Herpetological Journal , 6/4: 111-117.

Stevenson, C. 1999. "The Paleosuchus Page" (On-line ). Accessed 03/22/03 at http://crocodilian.com/paleosuchus/ .

Webb, G., C. Manolis, P. Whitehead. 1987. Wildlife Management: Crocodiles and Alligators . Australia: Surrey Beatty & Sons Pty Limited.

Webb, G., C. Manolis. 1998. Australian Crocodiles: A Natural History . Australia: Reed New Holland.