 An inhabitant of coastal continental and insular shelves , the sicklefin lemon shark occurs from the intertidal zone to a depth of 92 m ( 302 ft ) . This species favors still , murky waters and is most common in bays , estuaries , and lagoons , and over sandy flats and outer reefs . Sometimes , an individual may venture into open water ; one was filmed in the 1971 documentary Blue Water , White Death , in the vicinity of a sperm whale ( Physeter macrocephalus ) carcass . Juvenile sicklefin lemon sharks are often found on reef flats or around mangroves , in water so shallow that their dorsal fins are exposed . In Herald Bight off Western Australia , a known nursery , juvenile sicklefin lemon sharks frequent open areas and mangroves in water under 3 m ( 9 @.@ 8 ft ) deep , but not areas covered by the seagrass Posidonia australis . 
