Slender-Snouted Crocodile

Mecistops cataphractus, Critically Endangered

PHYSICALITY | ETYMOLOGY | TAXONOMY | RANGE | BEHAVIOR | DIET | REPRODUCTION | ECOSYSTEM | STATUS | IMAGES | FAUNAFACTS | VIDEO | SOURCES

The slender-snouted crocodile is distinct from other crocodiles because of its thin, slender snout. This nocturnal reptile is endemic to central Africa and can be found within neritic and coastal waters and along shorelines. As an ambush predator, this species waits submerged underwater with just its eyes and nostrils visible.

 

PHYSICALITY

As the common name suggests, the slender-snouted crocodile can be distinguished from other crocodile species by its extremely long, slender snout which lacks any bony ridges. It can also be distinguished by its dark, olive-colored back and bright yellow-colored ventral surface, which also shows several dark patches.

Slender-snouted crocodilians have an extremely powerful bite force and their mouths are equipped with many sharp teeth that are designed for grabbing and hanging on to their prey. They also continuously grow new teeth to replace any that are lost through fighting or feeding.

Slender-snouted crocodiles are small to medium-sized crocodilians, with a maximum recorded length of approximately 4 meters. Individuals over 3-3.5 meters are now rare, however.

As in all crocodilian species, sexual dimorphism is present in slender-snouted crocodiles with males being larger than females of the same age class.

No reliable information is available regarding the average lifespan of wild slender-snouted crocodiles, but captive individuals have been documented to live for at least 38 years.

BODY LENGTH
3-4 m. / 10-13 ft.
SEXUAL DIMORPHISM
Larger Males

ALTERNATE NAMES
African Slender-Snouted Crocodile
West African Slender-Snouted Crocodile
GROUP
Bask, Congregation
MALE
Bull
FEMALE
Cow
YOUNG
Crocklet
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES
Animalia
Chordata
Reptilia
Crocodylia
Crocodylidae
Mecistops
Cataphractus
ETYMOLOGY

The slender-snouted crocodile’s scientific name is Mecistops cataphractus.

As the common name suggests, the slender-snouted crocodile can be distinguished from other crocodile species by its extremely long, slender snout which lacks any bony ridges. It can also be distinguished by its dark, olive-colored back and bright yellow-colored ventral surface, which also shows several dark patches.

TAXONOMY

Recent 2006 DNA and morphological studies suggest that slender-snouted crocodiles constitute a distinct monotypic genus, for which the authors proposed to use the previously published name Mecistops. This finding has been supported by all subsequent molecular phylogentic analysis and studies. Thus, Mecistop has gained wide use and acceptance in the literature.

This change has not yet been adopted by the International Code for Zoological Nomenclature (ICZN), and most authors continue to use the genus name Crocodylus when referring to this species.

A recent 2013 study has found significant molecular and morphological support for two divergent taxa in this genus – one distributed entirely in West Africa and the other in Central Africa. Formal taxonomic revisions and recognition of these two unique taxa are expected soon.

 

GEOGRAPHIC RANGE

 

 

REGION

Slender-snouted crocodiles are native to central Africa, from as far west as Senegal, to Tanzania in the east, as far north as Chad, Mali, and Mauritania, and as far south as Zambia and Angola.

The Saint Paul, Mafa, and Saint John Rivers are all Liberian rivers in which this species occurs. Slender-snouted crocodiles have also been reported in areas of Cameroon and Gabon.

Historically, the slender-snouted crocodile was widely distributed throughout West and Central Africa, but recent surveys suggest that its distribution has changed as a result of local extirpations. The most comprehensive ecological studies on wild individuals were completed in 1989 and 2013.

The two regions, West and Central Africa, are completely isolated from each other underpinning the impending species split in this taxon. Central African habitats and populations do not seem to be fragmented despite some evidence for genetic isolation between major basins. In contrast, West African populations are highly fragmented due to a combination of severely fragmented forest habitats and the geology of the region and species-specific habitat use. For example, most major forested waterways throughout West Africa, especially in the Upper Guinea forest region, run north to south and show virtually no longitudinal communication except through the ocean which does not seem to be frequented by the slender-snouted Crocodile.

HABITAT

Slender-snouted crocodiles inhabit forest, savanna, inland wetlands, marine neritic, and marine coastal/supratidal habitats.

They are primarily found in tropical rainforests along the shores of shallow rivers and larger bodies of water, but also in lightly covered savanna woodlands. They are most frequently found in freshwater environments and occasionally in brackish waters of coastal lagoons.

They are primarily found in tropical rainforests along the shores of shallow rivers and larger bodies of water, but also in lightly covered savanna woodlands. They are most frequently found in freshwater environments and occasionally in brackish waters of coastal lagoons.

When these crocodiles leave the water they tend to stay in sheltered or protected areas to avoid predation. In the water, they usually swim just below the surface.

 

CO-HABITANTS

 

BEHAVIOR

Due to their limbs being short relative to the size of the rest of their body, slender-snouted crocodiles move somewhat awkwardly outside of the water. Despite this hinderance, they have several different forms of locomotion on land. Mainly, slender-snouted crocodiles will belly crawl through mud or on the banks of a river. They may also high walk by standing straight up on all four legs to move around on rougher, rockier terrain.

While swimming, slender-snouted crocodiles move in a very graceful, serpentine motion through the water. Power for forward propulsion is provided by the tail, with the limbs providing very little, if any, aid in swimming.

Little research has been conducted on communication in slender-snouted crocodiles. However, most crocodile species show common communication methods.

Hearing is very well-developed in crocodilians and is more sensitive than in other reptiles. Newly hatched young communicate with their mothers through high-pitched squeaks. Crocodilians also vocalize during aggressive interactions and while attempting to attract mates.

Vision plays an integral role in crocodilian communication, with males showing their dominance to intruders using different rituals, including raising their bodies out of the water to try to appear larger to intimidate their intruders. During mating season, crocodilian species perform visual displays to attract potential mates. When above the surface of the water, vision is an important pathway for perception of a crocodilian’s environment. It’s assumed that crocodilians can see in color because their eyes have both rods and cones. Their eyes also contain a tapetum lucidum, a layer of guanine-rich retinal cells that amplify incoming light and greatly improve night vision. However, when hunting underwater, a semi-transparent third eyelid closes over the eye, likely limiting vision to light/dark differentiation. Touch receptors and the ears are likely to be the primary sense organs used while crocodilians are underwater.

Although reliable information regarding specific sizes of home ranges and territories is sparse for crocodilians, all species, including slender-snouted crocodiles, display dominance hierarchies between males. Male slender-snouted crocodilians are very territorial and will not tolerate other males or intruders in their territories. This often leads to battles between dominant crocodiles and intruders. Males show their dominance to intruders using different rituals, including raising their bodies out of the water to try to appear larger in order to intimidate their intruders. Males will only live near females during mating seasons, passing from female to female within their territory. Dominant males will breed with all of the females within their territory.

 

DIET

Slender-snouted crocodiles have a carnivorous, predatory diet which, when young, consists mainly of aquatic species, particularly fish and small crustaceans. At larger sizes they feed on terrestrial mammals that drink from the rivers and lakes where the crocodiles live, such as water chevrotains (Hyemoschus aquaticus).

As with all other crocodilians, the head of the slender-snouted crocodile is well-suited for its ambush predatory lifestyle, with nostrils that sit high on the tip of the snout and eyes that face forward at the top of its head. This allows it to lie in wait at the edge of the water and stalk its prey while the rest of the body is almost completely submerged underwater, sit-and-wait style.

Slender-snouted crocodilians have an extremely powerful bite force and their mouths are equipped with many sharp teeth that are designed for grabbing and hanging on to their prey. They also continuously grow new teeth to replace any that are lost through fighting or feeding.

When hunting animals that are taking a drink of water from the banks of the river, slender-snouted crocodiles will quietly wait for an opportunity to lunge from the water and strike, striking when the prey animal dips its head to drink.

The stomachs of slender-snouted crocodiles and other crocodilian species often contain gastroliths (rocks held in the digestive tract) of various sizes. Although the purpose of these stones has yet to be confirmed, it appears likely that they serve to grind and break down food in the digestive tract, as is the case in other groups, such as herbivorous birds, seals, and sea lions, where they have been found.

Slender-snouted crocodilians do not secrete chitinases, so any chitinous or keratinous substances such as hair or mollusk shells accumulate in the gut and are most likely ejected through the mouth (which has been observed many times in captive individuals).

 

REPRODUCTION

Little is known about the specific courtship and mating systems of slender-snouted crocodiles.

Slender-snouted crocodiles are considered to be sexually mature when they reach 2.0 to 2.5 meters in length, typically at 10-15 years.

Reproduction generally takes place at the start of the rainy season, oogenesis in females and spermatogenesis in males beginning in January and February. Copulation generally occurs soon after. After copulation, the embryo and its surrounding eggshell begin to develop. Two to three months later, around April, egg-laying occurs. The entire process lasts until July.

In general, crocodilians engage in mating rituals that include sex-specific interactions, performing visual displays to attract potential mates. Females approach males in the water and begin the courtship ritual. During this courtship, crocodilians perform several activities involving swimming around each other and bodily contact. The female may even briefly swim away to encourage the male to chase her before continuing to circle. Following these ritualistic behaviors, the male places his tail under the female’s body for stability in shallow waters and the pair then begins copulation. Crocodilians have been observed copulating on their sides, either with the male on top of the female, or with the female on top of the male.

Nesting

Slender-snouted crocodile nests are made by the female, primarily using her hind legs to construct the nest of dead vegetation and mud. They are typically 50 to 80 centimeters high, 130 to 220 centimeters long, and 120 to 200 centimeters wide.

All crocodilian species, included the slender-snouted crocodile, lay eggs, with the temperature of nesting conditions determining the sex of hatchlings. Slender-snouted crocodile nests house incubating eggs for 90 to 100 days. During incubation, mother slender-snouted crocodiles try to keep egg temperatures between 27.4º Celsius and 34º Celsius by keeping them in the nest. The nest is kept moist by rainfall and humidity, helping to insulate it and keeping internal temperatures far more stable than temperatures outside the nest. Female crocodilians of various species, included slender-snouted crocodiles, have shown evidence that the nests of some species may be shared between multiple females. It’s believed that these species share nests to allow better deterrence of predators.

Among species in the genus Crocodylus, slender-snouted crocodiles produce the lowest average number of eggs per clutch but also exhibit the largest average egg size. Little information is available on the average number of eggs in a clutch, although one study found clutch sizes of 8, 17, and 22 eggs. On average, eggs measure approximately 8 centimeters long and 5 centimeters wide.

After a nest has been made and a clutch has been laid, slender-snouted crocodilian mothers guard their nests regularly throughout the incubation period. Soon after the slender-snouted crocodile offspring hatch, they begin to make squeaking noises, triggering the female to uncover the nest. If some of the hatchlings show no sign of emerging, the mothers will carefully place these eggs in their mouths and crack them. Soon after the offspring hatch, the mother scoops the hatchlings into her jaws and carries them to the water. Newborns are defended and cared for by both parents for some time after this relocation occurs.

Offspring

Newly emerged hatchlings measure 28 to 35 centimeters long. Young slender-snouted crocodilian hatchlings resemble mature adults, except smaller. Young slender-snouted crocodiles are fully capable of feeding and swimming from the moment that they hatch. The time for hatchlings to reach independence is unknown, but they have been found near the nest for as long as two weeks after hatching.

 

MATING SYSTEM
Polygynous
SEXUAL MATURITY
10-15 Years / 2-2.5 Meters
INCUBATION
90-100 Days

 

ECOSYSTEM ROLES

Predation on crocodilians occurs mainly at the egg or hatchling stage. Various animals feed on the eggs of slender-snouted crocodiles, including spotted-necked otters (Hydrictis maculicollis), leopards (Panthera pardus), and various bird and rodent species. Recent hatchlings face many of the same predators, as well as potential cannibalism by larger conspecifics. The large size and heavy scales of adults likely protects them from predation by other species, with the exception of humans, who hunt slender-snouted crocodiles for their skin and meat.

As with all crocodilian species, adult slender-snouted crocodiles are capable of severely injuring or killing humans.

Slender-snouted crocodiles provide two major economic benefits, skin and meat.

Slender-snouted crocodile skin is very valuable due to its durability and coloring and is often used to make various clothing items and accessories. Protective scales cover the slender-snouted crocodile’s skin, some of which are reinforced by bony plates to provide extra support. The snout lacks bony ridges, however. The large size and heavy scales of adults likely protects them from predation by other species, with the exception of humans, who hunt slender-snouted crocodiles for their skin and meat.

There was extensive, post WWII skin trading that was happening throughout West and Central Africa and did not slow down until the mid-1980s. The majority of this trade was in Nile crocodile (Crocodylus niloticus) products, but in certain parts of this range, such as Gabon, Côte d’Ivoire, Liberia, and the Congos, the slender-snouted crocodile was actually the primary traded species or heavily incidentally impacted. It is suspected that the slowdown of this trade in the 1980s was largely due to the significant reduction in crocodile populations, such as reduced efficiency and hunting output, and only partially due to international, CITES, and national legislative policies.

The meat of slender-snouted crocodiles also provides a means of sustenance in many areas. Long-running bushmeat studies in Gabon, Congo, and the Democratic Republic of the Congo continually find adult Slender-snouted Crocodiles for sale in markets. In contrast, this species has not been detected in the bushmeat trade in West Africa for some time indicating it is not reliably available as a target species.

 

PREDATORS

STATUS
LC NT VU EN CR EW EX

In 1996, there was not enough information on the Slender-snouted Crocodile. Some research in the early 1990’s suggested that slender-snouted crocodiles were severely depleted in West Africa, while a separate study in 2003 indicated that they were quite abundant in some parts of Gabon. As such, it was last assessed as Data Deficient on the 1996 International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species.

Since that time, particularly in the last six years, sufficient information has been collected to review its status. As such, an updated assessment was the highest priority recommendation for this species in the 2010 IUCN SSC Crocodile Specialist Group Action Plan update.

Based on known extensive trade in crocodile skins and other products, as well as habitat alteration and human encroachment since 1938, the slender-snouted crocodile meets the criteria for listing as Critically Endangered as it is inferred to have undergone a past population reduction of between 50-80% based on direct observation, loss of range and suitable habitat, direct exploitation and the impacts of introduced species. The reduction is closer to 50–60% for Central Africa and 70–90% for West Africa.

 

THREATS

The slender-snouted Crocodile, particularly throughout West Africa, is incredibly shy and susceptible to human disturbance. As human populations throughout its distribution grow and occupy what were previously gallery forests and other forested wetland habitats this species is pushed out or hunted to local extinctions. In West Africa the extent of occurrence in the north of this species range has already declined drastically due to aridification and human settlement. It is projected that this species will likely be lost from the non-true forested areas, such as the wooded, gallery savanna areas in the north of its West African range in the next 10–20 years if it currently still exists in these northern extremes. Additionally, surveys prior to 2005 already suggested that the slender-snouted Crocodile may no longer occur in the Lake Mweru basin or throughout Lake Tanganyika. While very little historic survey data exists, that which does and can be compared to contemporary surveys show that populations are declining.

Based on the current estimated subpopulation declines and local extinctions throughout the Sahel, Lake Mweru, and Lake Tanganyika it is anticipated that slender-snouted crocodile subpopulations will become extinct within one generation into the future.

Additionally, while the Sene-Gambia subpopulation is currently well protected, any loss of will to continually protect the chimpanzee (Pan troglodytes) colonies will result in near instantaneous extinction of this subpopulation. Slender-snouted crocodiles are significantly reduced in at least the Sahel zone and Lake Tanganyika and Mweru locations with anticipated complete extirpation in the near future.

There is also continuing decline in the extent and quality of the habitat based on deforestation and forest degradation throughout this species range, especially in West Africa, which has resulted in sedimentation effecting prey species populations, as well as human settlement/encroachment and reduction in breeding habitat.

There is no reason to expect the decline to slow, hence future reduction over the next 75 years, or three generations, is projected to be between 60–90% based on ongoing loss of range and habitat, exploitation and competition with other introduced crocodilian species. The future reduction is hard to quantify mostly due to extremely different threats and levels of active protection between West and Central Africa. On a global basis, however, this species is expected to lose 100% of mature individuals outside of protected areas and 60–90% inside of protected areas where fishing, hunting, and forest clearing remain issues.

In West Africa, subpopulations have already been reduced to the point where even small perturbations will result in localized extinctions and the state of protected area management (where most individuals are confined today) suggests that these reductions will continue into the future. For example, this species continues to exist in The Gambia solely due to the level of protection afforded the artificial chimpanzee colonies on the islands on which it breeds in the interior of the River Gambia National Park – it does not occur up or downstream of these core islands. Additionally, with increasing habitat conversion the West African crocodile (Crocodylus suchus) will be able to occupy previously exclusive slender-snouted crocodile habitat and out-compete them. Without intervention, in Central Africa the only remaining subpopulations at the end of three generations will be restricted to well-managed protected areas and remote areas of Gabon. In West Africa, this species is anticipated to go completely extinct without significant revisions in protected area policy and management, as well as assisted efforts such as reintroductions.

Looking at a combination of the information on past and future reductions it is estimated that population reduction would be between 50–80%, once again resulting in a Critically Endangered listing. From 2013 to 2035 it is estimated that continued habitat loss, habitat conversion for agriculture, such as for palm oil and rubber developments throughout Gabon, the Democratic Republic of the Congo, Cote d’Ivoire, Liberia and Sierra Leone, and increasing human pressures on natural resources, notably freshwater fisheries, will greatly increase this species extinction risk.

CONSERVATION

To date, the only known conservation actions for the slender-snouted crocodile are not targeted specifically at it but rather at communities and landscapes such as national parks and national legislation.

A recently renewed initiative in Côte d’Ivoire is looking at captive breeding and reintroduction.

The slender-snouted crocodile is listed on CITES Appendix I.

 

IMAGES

 

 

FAUNAFACTS
Slender-Snouted Crocodile - Hearing is very well developed in slender-snouted crocodiles, likely to be the primary sense organ when underwater, and is more sensitive than in other reptiles.
Slender-Snouted Crocodile Slender-Snouted Crocodile - Female slender-snouted crocodiles construct 120-200 cm. wide nests of dead vegetation and mud using their hind legs.
Slender-Snouted Crocodile Slender-Snouted Crocodile - Due to their limbs being short relative to the size of their body, slender-snouted crocodiles move awkwardly outside of the water, belly crawling through mud and high walking over rocks.

 

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