The large eyes of crocodile sharks suggest that it is a visual hunter, specializing in bioluminescent and light-refracting prey (Martin 2003). Additionally, the crocodile shark is electroreceptive; it can sense changes in the surrounding electrical field (Martin 2003). Sharks, in general, also have a keen sense of chemical perception.
Communication Channels: visual ; electric
Other Communication Modes: photic/bioluminescent
Perception Channels: visual ; tactile ; chemical ; electric
Due to small size and wide range in habitat, very little information has been accumulated on crocodile sharks. The current population size is unknown, however, crocodile sharks are vulnerable to catching by long-line fisheries (Martin 2003). There is no information to indicate trends in population size, but due to bycatch a population decline is probable (Compagno 2002). As a result, the IUCN Red List of Threatened Species has labeled crocodile sharks at low risk for extinction.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: near threatened
At birth, crocodile sharks are 41 cm in length (Compagno 1984). Males mature at a length of about 74 to 100 cm and females mature at a length of about 89 to 102 cm (Martin 2003).
Development - Life Cycle: indeterminate growth
Crocodile sharks have never been implicated in attacks on humans and are deemed harmless (Martin 2003). Thus, there are no known adverse effects of crocodile sharks on humans.
Crocodile sharks do not provide many benefits to humans; their large, squalene-rich liver is a source of potential value (Martin 2003). However, crocodile sharks generally are discarded due to their small size and useless flesh (Compagno 1984).
Positive Impacts: body parts are source of valuable material
Very little is known about the role crocodile sharks play in the ecosystem to which they belong. However, sharks in general are usually important predators in aquatic ecosystems (Martin 2003).
Crocodile sharks are carnivores; they eat small bony fish, squids, and shrimp (Compagno 1984). They have protrusible and muscular jaws that suggest they are capable of eating a wide variety of prey (Martin 2003). Beyond this, very little is known about the specific feeding habits of crocodile sharks.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Molluscivore )
Pseudocarcharias kamoharai (Crocodile sharks) can be found in nearly all subtropical and tropical oceans of the world (Compagno 1984).
Biogeographic Regions: palearctic (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native ); indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Crocodile sharks are mostly pelagic; however, there have been some incidences where crocodile sharks have been found inshore (Compagno 1984). The known depth range of crocodile sharks from the water surface can reach 590 m (Martin 2003).
Range depth: 590 (high) m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: pelagic
There are no data on the lifespan/longevity of crocodile sharks.
Crocodile sharks are clearly distinguishable by huge eyes that lack nictitating eyelids and long gill slits that extend to the top of the head. Crocodile sharks have a slender, spindle-shaped body with two small, spineless dorsal fins. The second dorsal fin is less than half the size of the first dorsal fin. The pelvic fins are distinctly broad and round (Compagno 1984). Like all Lamniformes, crocodile sharks have 5 gill slits and a mouth that extends behind the eyes (Martin 2003). The size of adult crocodile sharks is on average 89 to 110 cm in length and between 4 to 6 kg in weight. The color of crocodile sharks can range from light to dark grey to dark brown. White or transluscent margins may also be found around the fins (Martin 2003). Some specimens have been found with whitish blotches on either side of the head between the corner of jaw and the first gill slit (Compagno 1984).
Range mass: 4 to 6 kg.
Range length: 89 to 110 cm.
Average length: 105 cm.
Other Physical Features: endothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
Very little is known about any anti-predator adaptations that the crocodile shark may exhibit. However, when removed from water, the crocodile shark snaps its powerful jaw vigorously, almost like a "crocodile." This may serve as a defense mechanism to fight off predators (Martin 2003). There are no known predators of crocodile sharks.
Crocodile sharks reproduce sexually through internal fertilization. There is little information on the mating systems of P. kamoharai.
Crocodile sharks reproduce sexually through internal fertilization. Females are ovoviviparous; they retain the eggs of their offspring until they hatch (Martin 2003). Females exhibit aplacental viviparity; the developing embryos lack a connection to the mother and thus feed on the yolk sac and the other ova produced by the mother (oophagy)(Compagno 1984). The mother typically produces four pups per litter; the pups are miniature adults, capable of swimming and feeding (Martin 2003).
Range number of offspring: 2 to 4.
Average number of offspring: 4.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); ovoviviparous
Like all sharks, the crocodile shark provides no parental care after birth.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)
