Animal Diversity Web

Ge­o­graphic Range

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. (Aber­crom­bie, 1976; Groom­bridge, 1982; Kofron, 1992; Pauwels, et al., 2003; Radley and Sher­lock, 2001)

• Biogeographic Regions
• ethiopian
  • native

Habi­tat

Slen­der-snouted croc­o­diles 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. (Groom­bridge, 1982; Kofron, 1992; Radley and Sher­lock, 2001)

• Habitat Regions
• tropical
• terrestrial
• freshwater

• Terrestrial Biomes
• rainforest

• Aquatic Biomes
• rivers and streams
• brackish water

• Wetlands
• swamp

Phys­i­cal De­scrip­tion

Slen­der-snouted croc­o­diles are small to medium-sized croc­o­dil­ians, with a max­i­mum recorded length of ap­prox­i­mately 4 me­ters. Sex­ual di­mor­phism is pre­sent (as in all croc­o­dil­ian species), with males being larger than fe­males of the same age class. As the com­mon name sug­gests, this species has a long, slen­der snout. Pro­tec­tive scales cover the skin, some of which are re­in­forced by bony plates to pro­vide extra sup­port. The head is equipped with nos­trils that sit high on the tip of the snout and eyes that are arranged fac­ing for­ward at the top of the head. (Grigg and Gans, 1993; Kelly, 2006; Radley and Sher­lock, 2001; Wait­kuwait, 1989)

Slen­der-snouted croc­o­diles can be dis­tin­guished from other croc­o­dile species by their ex­tremely slen­der snout, which lacks any bony ridges, as well as their dark, olive-col­ored back and bright yel­low-col­ored ven­tral sur­face, which also shows sev­eral dark patches. (Steel, 1989)

• Other Physical Features
• ectothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range length

  3 to 4 m

  9.84 to 13.12 ft

De­vel­op­ment

All croc­o­dil­ian species lay eggs, with the tem­per­a­ture of nest­ing con­di­tions de­ter­min­ing the sex of hatch­lings. Young croc­o­dil­ian hatch­lings re­sem­ble ma­ture adults, ex­cept smaller. They are fully ca­pa­ble of feed­ing and swim­ming from the mo­ment that they hatch. Slen­der-snouted croc­o­diles are con­sid­ered to be sex­u­ally ma­ture when they reach 2.0 to 2.5 me­ters in length. (Kelly, 2006; Wait­kuwait, 1989)

• Development - Life Cycle
• temperature sex determination
• indeterminate growth

Re­pro­duc­tion

Lit­tle is known about the spe­cific courtship and mat­ing sys­tems of slen­der-snouted croc­o­diles. In gen­eral, croc­o­dil­ians en­gage in mat­ing rit­u­als that in­clude sex-spe­cific in­ter­ac­tions. 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, and 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. (Grigg and Gans, 1993; King and Dobbs, 2007; Wait­kuwait, 1989)

• Mating System
• polygynous

Slen­der-snouted croc­o­diles typ­i­cally reach sex­ual ma­tu­rity at 10 to 15 years. Re­pro­duc­tion gen­er­ally takes place at the start of the rainy sea­son. The en­tire process be­gins in Jan­u­ary or Feb­ru­ary and lasts until July. Oo­ge­n­e­sis in fe­males and sper­mato­ge­n­e­sis in males be­gins 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. (Wait­kuwait, 1985; Wait­kuwait, 1989)

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 cm high, 130 to 220 cm long, and 120 to 200 cm wide. Nests house in­cu­bat­ing eggs for 90 to 100 days. 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 cm long and 5 cm wide. 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. (Thor­b­jarnar­son, 1996; Wait­kuwait, 1985; Wait­kuwait, 1989)

Dur­ing in­cu­ba­tion, moth­ers try to keep egg tem­per­a­tures be­tween 27.4ºC and 34ºC by keep­ing the eggs in the nest. The nest is kept moist by rain­fall and hu­mid­ity, help­ing to in­su­late the nest and keep­ing in­ter­nal tem­per­a­tures far more sta­ble than tem­per­a­tures out­side the nest. Newly emerged hatch­lings mea­sure 28 to 35 cm long. 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. (Wait­kuwait, 1985; Wait­kuwait, 1989)

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

• Breeding interval

  Slender-snouted crocodiles reproduce once yearly in the rainy season

• Breeding season

  January-July

• Range number of offspring

  8 to 22

• Range gestation period

  60 to 90 days

• Range age at sexual or reproductive maturity (female)

  10 to 15 years

• Range age at sexual or reproductive maturity (male)

  10 to 15 years

After a nest has been made and a clutch has been laid, croc­o­dil­ian moth­ers guard their nests reg­u­larly through­out the in­cu­ba­tion pe­riod. Soon after the 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 mouth and crack them. The mother then 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. (Grigg and Gans, 1993; Thor­b­jarnar­son, 1996; Wait­kuwait, 1985; Wait­kuwait, 1989)

• Parental Investment
• male parental care
• female parental care
• pre-hatching/birth
  • protecting
    • female
• pre-weaning/fledging
  • protecting
    • female
• pre-independence
  • protecting
    • male
    • female

Lifes­pan/Longevity

No re­li­able in­for­ma­tion is avail­able re­gard­ing the av­er­age life span of wild slen­der-snouted croc­o­diles. Cap­tive in­di­vid­u­als have been doc­u­mented to live for at least 38 years. (King and Dobbs, 2007)

• Range lifespan
  Status: captivity

  32 to 38 years

Be­hav­ior

Al­though they move some­what awk­wardly out­side of the water, due to their limbs being short rel­a­tive to the size of the rest of their body, slen­der-snouted croc­o­diles have sev­eral dif­fer­ent lo­co­mo­tory modes on land. Mainly, they belly crawl through mud or on the banks of a river. How­ever, they can also high walk by stand­ing straight up on all four legs to move around on rougher, rock­ier ter­rain. While swim­ming, they 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. (Grigg and Gans, 1993; Kelly, 2006; Wait­kuwait, 1989)

The head of croc­o­dil­ians is well-suited for their sit-and-wait preda­tory life style, with nos­trils that sit high on the tip of the snout and eyes that face for­ward at the top of their head. This al­lows them to be able to stalk their prey while the rest of their body is sub­merged under water. When hunt­ing an­i­mals that are tak­ing a drink of water from the banks of the river, they will qui­etly wait for an op­por­tu­nity to lunge from the water and strike. (Grigg and Gans, 1993; Kelly, 2006; Wait­kuwait, 1989)

Male croc­o­dil­ians do not tol­er­ate other males and will only live near fe­males dur­ing mat­ing sea­sons, pass­ing from fe­male to fe­male within their ter­ri­tory. Fe­male croc­o­dil­ians of var­i­ous species 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. (Wait­kuwait, 1989)

• Key Behaviors
• natatorial
• nocturnal
• motile
• sedentary
• territorial
• dominance hierarchies

Home Range

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 croc­o­dil­ians are very ter­ri­to­r­ial and dom­i­nant males will not tol­er­ate in­trud­ers in their ter­ri­tory, which often leads to a bat­tle be­tween the dom­i­nant croc­o­dile and the in­truder. Dom­i­nant males will breed with all of the fe­males within their ter­ri­tory. (Grigg and Gans, 1993; Kelly, 2006; Wait­kuwait, 1989)

Com­mu­ni­ca­tion and Per­cep­tion

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, with newly hatched young com­mu­ni­cat­ing with their mother through high-pitched squeaks. Croc­o­dil­ians also vo­cal­ize dur­ing ag­gres­sive in­ter­ac­tions and while at­tempt­ing to at­tract mates. (Grigg and Gans, 1993; Kelly, 2006; Wait­kuwait, 1989)

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. (Grigg and Gans, 1993; Kelly, 2006; Wait­kuwait, 1989)

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. (Grigg and Gans, 1993)

• Communication Channels
• visual
• tactile
• acoustic

• Other Communication Modes
• vibrations

• Perception Channels
• visual
• tactile
• acoustic
• vibrations

Food Habits

Slen­der-snouted croc­o­diles have a preda­tory diet which, when young, con­sists mainly of fish and small crus­taceans. At larger sizes they feed on mam­mals that drink from the rivers and lakes where the croc­o­diles live, such as water chevro­tains (Hye­moschus aquati­cus). The place­ment of the eyes and nos­trils atop the head and snout, re­spec­tively, al­lows slen­der-snouted croc­o­diles (and all other croc­o­dil­ians) to lie in wait at the edge of the water while al­most com­pletely sub­merged, strik­ing when the prey an­i­mal dips its head to drink. 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. (Pauwels, et al., 2003; Wait­kuwait, 1989)

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). 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 (her­biv­o­rous birds, seals, sea lions) where they have been found. (Grigg and Gans, 1993; Pauwels, et al., 2003; Platt, et al., 2002)

• Primary Diet
• carnivore
  • eats terrestrial vertebrates
  • piscivore

• Animal Foods
• mammals
• amphibians
• reptiles
• fish
• insects
• aquatic crustaceans

Pre­da­tion

Pre­da­tion on croc­o­dil­ians oc­curs mainly at the egg or hatch­ling stage. Var­i­ous an­i­mals feed on the eggs of slen­der-snouted croc­o­diles, in­clud­ing 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. (Pauwels, et al., 2003; Wait­kuwait, 1989)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • spotted necked otters (Hydrictis maculicollis)
  • leopards (Panthera pardus)
  • slender-snouted crocodiles (Mecistops cataphractus)
  • humans (Homo sapiens)

Ecosys­tem Roles

Slen­der-snouted croc­o­diles are preda­tors of many aquatic species (par­tic­u­larly fishes), as well as some ter­res­trial mam­mals. Young in­di­vid­u­als and eggs serve as prey to fish, birds, mam­mals, and larger croc­o­diles. (Grigg and Gans, 1993; Junker and Boomker, 2006; Pauwels, et al., 2003)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Slen­der-snouted croc­o­diles pro­vide two major eco­nomic ben­e­fits. Their skin is very valu­able due to its dura­bil­ity and col­or­ing and is often used to make var­i­ous cloth­ing items and ac­ces­sories. The meat of slen­der-snouted croc­o­diles also pro­vides a means of sus­te­nance in many areas. (Aber­crom­bie, 1976; Pauwels, et al., 2003; Wait­kuwait, 1989)

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

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

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

• Negative Impacts
• injures humans
  • bites or stings

Con­ser­va­tion Sta­tus

Pop­u­la­tions of slen­der-snouted croc­o­diles ap­pear to be in a slow de­cline, mainly due to habi­tat loss caused by hu­mans. How­ever, there is not enough in­for­ma­tion on the species to know whether to place it within the en­dan­gered, vul­ner­a­ble or rare cat­e­gory of the IUCN redlist. 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 are quite abun­dant in some parts of Gabon. (Kofron, 1992; Pauwels, et al., 2003)

• IUCN Red List

  Data Deficient

• US Federal List

  No special status

• CITES

  Appendix I

• State of Michigan List

  No special status

Other Com­ments

A re­cent mol­e­c­u­lar phy­lo­ge­netic analy­sis sug­gested that slen­der-snouted croc­o­diles con­sti­tute a dis­tinct genus, for which the au­thors pro­posed to use the pre­vi­ously pub­lished name Mecistops. 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. (McAliley, et al., 2006)

Con­trib­u­tors

Joel Lavin­der (au­thor), Rad­ford Uni­ver­sity, Joshua Pen­ning­ton (au­thor), Rad­ford Uni­ver­sity, Chris­tine Small (ed­i­tor), Rad­ford Uni­ver­sity, Je­remy Wright (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Aber­crom­bie, C. 1976. Notes on west African croc­o­dil­ians (Rep­tilia, Croc­o­dilia). Jour­nal of Her­petol­ogy, 12: 260-262.

Co­nant, R., R. Hud­son. 1949. Longevity records for rep­tiles and am­phib­ians in the Philadel­phia Zo­o­log­i­cal Gar­den. Her­peto­log­ica, 5: 1-8.

Grigg, G., C. Gans. 1993. Mor­phol­ogy and phys­i­ol­ogy of the Croc­o­dylia. Pp. 326-336 in C Glasby, G Ross, P Beesley, eds. Fauna of Aus­tralia, Vol. 2A, Am­phibia and Rep­tilia. Can­berra, Aus­tralia: Aus­tralian Gov­ern­ment Pub­lish­ing Ser­vice.

Groom­bridge, B. 1982. The IUCN Am­phibia-Rep­tilia Red Data Book. Wok­ing, Sur­rey, U.K.: Unwin Broth­ers Lim­ited.

Junker, K., J. Boomker. 2006. A check-list of the pen­tas­to­mid par­a­sites of croc­o­dil­ians and fresh­wa­ter ch­e­lo­ni­ans. On­der­stepoort Jour­nal of Vet­eri­nary Re­search, 73: 27-36.

Kelly, L. 2006. Croc­o­dile: Evo­lu­tion's Great­est Sur­vivor. Crows Nest, N.S.W: Allen & Unwin.

King, F., J. Dobbs. 2007. Croc­o­dil­ian prop­a­ga­tion in Amer­i­can zoos and aquaria. In­ter­na­tional Zoo Year­book, 15/1: 272-277.

Kofron, C. 1992. Sta­tus and habi­tats of the three African croc­o­diles in Liberia. Jour­nal of Trop­i­cal Ecol­ogy, 8/3: 265-273.

Mar­tin, S. 2008. Global di­ver­sity of croc­o­diles (Croc­o­dilia, Rep­tilia) in fresh­wa­ter. De­vel­op­ments in Hy­dro­bi­ol­ogy, 198/595: 587-591.

McAliley, L., R. Willis, D. Ray, P. White, C. Brochu, L. Dens­more III. 2006. Are croc­o­diles re­ally mono­phyletic? - Ev­i­dence for sub­di­vi­sions from se­quence and mor­pho­log­i­cal data. Mol­e­c­u­lar Phy­lo­ge­net­ics and Evo­lu­tion, 39: 16-32.

Pauwels, O., V. Ma­monekene, P. Du­mont, W. Branch, M. Burger, S. Lavoué. 2003. Diet records for Croc­o­dy­lus cat­aphrac­tus (Rep­tilia: Croc­o­dyl­i­dae) at Lake Di­van­gui Ogooué-Mar­itime province, south­west­ern Gabon. Hamadryad, 27/2: 200-204.

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

Pope, J. 2000. Croc­o­dile: Habi­tats, Life Cy­cles, Food Chains, Threats. Austin, TX: Rain­tree Steck-Vaughn.

Radley, G., J. Sher­lock. 2001. Wa­ter­ways. Min­neapo­lis, MN: Lerner Pub­lish­ing Group.

Riley, J., F. Huchz­er­meyer. 1999. African Dwarf Croc­o­diles in the Lik­ouala Swamp Forests of the Congo Basin: Habi­tat, Den­sity, and Nest­ing. Copeia, 1999/2: 313-320.

Steel, R. 1989. Croc­o­diles. Kent, U.K.: Christo­pher Helm Ltd..

Thor­b­jarnar­son, J. 1996. Re­pro­duc­tive char­ac­ter­is­tics of the Order Croc­o­dylia. Her­peto­log­ica, 52/1: 1/18.

Wait­kuwait, W. 1989. Croc­o­diles: Their Ecol­ogy, Man­age­ment, and Con­ser­va­tion. Gland, Switzer­land: In­ter­na­tional Union for Con­ser­va­tion of Na­ture and Nat­ural Re­sources.

Wait­kuwait, W. 1985. In­ves­ti­ga­tions of the breed­ing bi­ol­ogy of the west African slen­der-snouted croc­o­dile (Croc­o­dy­lus cat­aphrac­tus) Cu­vier, 1824. Am­phibia-Rep­tilia, 6/4: 387-399.