The Shark with sickle-shaped fins

The Sharptooth Lemon shark or Sicklefin Lemon shark (Negaprion acutidens) is a species of requiem shark belonging to the family Carcharhinidae, widely distributed in the tropical waters of the Indo-Pacific. It is closely related to the American Lemon shark. The main noticeable difference is the shape of its fins. They are sickle-shaped or falcate.


Family: Carcharhinidae – Requiem sharks

Genus: Negaprion

Species: acutidens


Phylum– Chordata

Class– Chondrichthyles



Common NameGround Sharks

Family– Carcharhinidae 

Common NameRequiem Sharks




Average Size and Length: The Sharptooth Lemon shark has been recorded at maximum known length of 12 feet. It typically doesn’t exceed 10 feet on average.

Average Weight:

Current Rare Mythical Sightings: On occasion, Sharptooth Lemon sharks may venture into open water. In the 1971 documentary, Blue Water, one was filmed in the same area of a Sperm whale carcass.

Teeth and Jaw: The Sharptooth Lemon shark has short furrows at the corners of its mouth. It has 13 to 16 (typically 14) tooth rows on either side of both jaws, not including the tiny teeth at the symphysis. The upper teeth have a large cusp rising from a broad base, with a notch on each side; these teeth become increasingly angled towards the corners of the mouth. The lower teeth are similar to the upper teeth but are narrower and more erect. The teeth of the sharks that are over 4.6 feet long are finely serrated.

Head: The Sicklefin Lemon shark or Sharptooth Lemon shark has a short, broad head. The snout is almost wedge-shaped and rounded. It has small nostrils with skin flaps, and small eyes without any spiracles.

Denticles: On the Sharptooth Lemon shark, the dermal denticles are large and overlapping and have 3 to 5 horizontal ridges.


Demographic, Distribution, Habitat, Environment and Range: The Sharptooth Lemon shark can be found from South Africa to the Red Sea, in places like Madagascar, Seychelles and Mauritius to Jeddah, Saudi Arabia, all the way to the coast east from the Indian continent to Southeast Asia, all the way north to the Philippines and Taiwan and as far south as northern Australia and New Guinea. It also loves Pacific islands like Palau, New Caledonia, the Marshall Islands, the Solomon Islands, Vanuatu, French Polynesia, and Fiji. It most likely colonized the central Pacific by island-hopping.

Sharptooth Lemon sharks prefer coastal continental and insular shelves. They can be found from the intertidal zone to a depth of 302 feet. It prefers the murky waters of bays, estuaries, lagoons, and over sandy flats and outer reefs.

Juvenile Sharptooth Lemon sharks or Sicklefin Lemon sharks are typically found on reef flats or around mangroves in extremely shallow water. Usually their dorsal fins are exposed; a documented nursery area of less than 9.8 feet open with mangroves, and in another nursery area, lacking seagrass.

Diet: The Sharptooth Lemon shark or Sicklefin Lemon shark eats mostly bottom dwelling and shore dwelling teleosts. Over 90 % actually. Some include mullets, herring, mackerel, silversides, needlefish, smelt-whitings, porgies, sea catfish, parrotfish, porcupinefish, and triggerfish. They may also eat on occasion crustaceans and cephalopods. There have been some reports of older, larger sharks eating guitarfish and stingrays.

Larger sharks are known to eat the Sharptooth Lemon shark or Sicklefin Lemon shark.

Ram-Suction Index:

Aesthetic Identification: The Sharptooth Lemon shark or Sicklefin Lemon shark is stalky and robust. It is brownish-yellowish to grey on top, and counter-shaded light below. The fins have much more prominent yellow.

The Sicklefin Lemon shark or Sharptooth Lemon shark has fins that are sickle-shaped. This is about the only aesthetic difference between them, and the American Lemon sharks we have here in Jupiter, Fl. The first dorsal fin is positioned closer to the pelvic than the pectoral fins. The second dorsal fin, nearly equal to the first in size, is located over or slightly forward of the anal fin. No ridge is seen between the dorsal fins. The pectoral fins are long and broad, originating below the space between the third and fourth gill slits. The anal fin has a strong notch in the rear margin. There is a longitudinal precaudal pit.

Biology and Reproduction: Regional subpopulations seem to stay mostly exclusive since there is a significant amount of genetic differences between the subpopulations of French Polynesia and Australia which are 470 miles apart.

The Sicklefin Lemon shark or Sharptooth Lemon shark can remain still on the sea floor, pumping water over its gills.

Known parasites include these tapeworms: Paraorygmatobothrium arnoldi, Pseudogrillotia spratti, Phoreiobothrium perilocrocodilus, and Platybothrium jondoeorum.

The Sicklefin Lemon shark or Sharptooth Lemon shark is viviparous. Females can have up to 13 (but usually 12) pups every other year. Their gestation period is between 10-11 months. There isn’t any evidence that they are philopatric, like the American Lemon shark. Parturition occurs in October or November at Madagascar and Aldabra, and in January at French Polynesia; ovulation and mating for nonpregnant females takes place at around the same time. Known nursery areas are shallow. Both males and females reach sexual maturity between 7.2 and 7.9 feet, and they do have a slow growth rate.

Behavioral Traits, Sensing and Intelligence: They typically stay within a 1-mile radius of their tagging location according to tagged shark data. In some locations, like the islands, they do seem more transient.

Sharptooth Lemon sharks or Sicklefin Lemon sharks do engage in mutualistic relationship. They engage in cleanings by bluestreak cleaner wrasses. The shark will open its mouth and stop respiring for just over 2 minutes to allow the fish access to their gills and mouths.

If it is provoked and wishes to pursue a target, the Sharptooth Lemon shark is extremely persistent.

It is typically shy and will tend to keep away from divers, however there was an account of a swimmer being forced on top of coral to get away from the shark. The shark circled for hours before giving up.

Speed: The Sharptooth Lemon shark is sluggish, and typically cruses slowly close to the sea floor, or will remain still on the bottom.

Sharptooth Lemon Shark Future and Conservation: The Sharptooth Lemon shark is threatened by over fishing, especially due to its lack of movement and slow reproductive rate. It is harvested using anchored and floating gillnets, beach nets, and longlines. The meat is sold fresh or dried and salted for human consumption, the fins used for shark fin soup, and the liver oil is processed for vitamins.

The Sharptooth Lemon shark or Sicklefin Lemon shark is also threatened by habitat degradation. Pollution, mangrove deforestation, and blast fishing on coral reefs are all real threats.

Sharptooth Lemon Shark Recorded Attacks on Humans: There are some reported unprovoked attacks on humans and is considered potentially dangerous. It will defend itself if it is spooked or touched.