Silvertip shark

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Silvertip shark
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species: C. albimarginatus
Binomial name
Carcharhinus albimarginatus
(Rüppell, 1837)
Range of the silvertip shark
Synonyms

Carcharias albimarginatus Rüppell, 1837
Eulamia platyrhynchus Gilbert, 1892

The Silvertip shark (Carcharhinus albimarginatus), is a large species of requiem shark, family Carcharhinidae, which is found in the Indian and Pacific Ocean. Sometimes confused with the Grey reef shark, this species of shark is known for the white tips on all of it's fins. With an average length of 2-2.5 metres, the Silvertip shark rarely reaches the length of 3 meters.

Taxonomy[change | change source]

The Silvertip shark was originally described as Carcharias albimarginatus by Eduard Rüppell, in 1837. This name was changed to the current Carcharhinus albimarginatus by Rüppell later that same year. The genus name Carcharhinus is derived from the Greek "karcharos" meaning "sharpen" and "rhinos" meaning "nose". The species name albimarginatus is from the Latin "albi" meaning "white" and "marginatus" meaning "to enclose with a border". Synonyms referring to this species in previous scientific literature include Eulamia platyrhynchus by Gilbert in 1892 and Carcharhinus platyrhynchus by Gilbert 1892. [1]

Description[change | change source]

The Silvertip shark is named for its white tips on its fins

The Silvertip shark is slender with a long and broadly rounded snout. The eyes are large and round. An interdorsal ridge is present on this species. The first dorsal fin is large with a pointed apex. It originates over or slightly in front of the free tips of the pectoral fins. The second dorsal fin originates over or just behind the origin of the anal fin. The pectoral fins are large and semifalcate with narrowly rounded or pointed tips. The caudal fin is asymmetrical in shape with a rather large upper lobe. The top of the body is dark grey or grey-brown with a bronzy sheen, and the underside is white. A white band, which is not clearly visible, is located on the flank region. This shark's name, "Silvertip shark", comes from the white tips on all of it's fins. The Silvertip shark may be confused with the Grey reef shark (Carcharhinus amblyrhynchos), however the Grey reef shark has dark tips on the pectoral fins and trailing edge of the caudal fin. Also, the Whitetip reef shark (Triaenodon obesus) is similar in appearance to the Silvertip shark. Although both shark species have white markings on the dorsal and caudal fins, the Whitetip reef shark doesn't have these markings on the tips of the pectoral fins. The Whitetip reef shark also has a more square-shaped snout. The Silvertip shark has 12-14 teeth on each jaw. The upper teeth are broad and strongly jagged. The cusps are high and triangular and the crown feet have rough serrations or low cusplets. The lower teeth have raised, broad serrated cusps with transverse roots. The Silvertip shark grows to a maximum length of 9.8 feet (3 m). However, the average length of this species is 6.6-8.2 feet (2-2.5 m). The maximum weight of the Silvertip shark is 358 pounds (162.2 kg).[1]

Habitat[change | change source]

Silvertip sharks are found over continental and insular (island) shelves and offshore banks. They are thought to prefer offshore islands, coral reefs and banks to depths of 800 m. They have been found in the western Indian Ocean: the Red Sea and of East Africa, including Madagascar, Seychelles, Aldabra Group, Mauritius and the Chagos Archipelago. In the western Pacific they are found off southern Japan to northern Australia and French Polynesia. In the eastern central Pacific they are found off southern Baja California, Mexico to Colombia, including the Cocos, Galápagos, and Revillagigedo Islands. [2]

Behaviour[change | change source]

This shark is a great hunter and is very stealth-like. They are usually found in shallow waters, making them one of the most commonly seen shark species by humans. Since of it's unpredictable behaviour and aggressive hunting tactics, this shark is considered to be a higher threat to humans than most other sharks.[3]

Feeding[change | change source]

Silvertip sharks are one of the main predators of the Spotted eagle ray

Prey of the Silvertip shark include benthic and midwater fish such as wahoo, eagle rays, wrasses, and tunas as well as small sharks. This shark also feeds on octopuses and squid. The Silvertip shark has been observed swimming along the edge of a group of other species of feeding sharks, taking food from them.[1]

Reproduction[change | change source]

The Silvertip shark is viviparous, meaning that they give live birth. Courtship is a little different in these sharks and these sharks are known to hold each other. Bites are normal, so much so that a female Silvertip shark has been found without a part of the dorsal fin after mating. Mating occurs in the summer. During the gestation period that could extend to a year, the embryos feed from the yolk and once the yolk is exhausted, the yolk-sac modifies itself into a placental connection through which the newborns feed from the mother. The newborns are born in litters (normally 5 to 6 but can be from 1 to 11) and are anywhere between 63 to 81 centimeters or 25 to 32 inches long. The females are considered sexually mature once they grow to be about 2 meters long and in the case of males, it is 1.8 meters. The pups are known to swim with the mother shark in shallow waters before becoming independent.[3]

Common names[change | change source]

In English, the Silvertip shark is also known as the "Silver-tip shark and the "White fin". In French it is known as "aileron blanc du récif" and "requin pointe blanche ". In Samoan it is "aso". "Bagea mara" is Gela, "cazon" is Spanish, "gursh" and "jarjur" is Arabic, "iho" is Surigaonon, "ikan yu" is Malay, "kattafulhi miyaru" is Maldivian, "marracho de pontas" is Portuguese, "mwoashog" is Carolinian, "pating" is Tagalog, "riff-weißspitzenhai" is German, "silwertiphaai" is Afrikaans, "te bakoa" is Kiribati, "tiburón de puntas blancas" is also Spanish, "tsumajiro" is Japanese, and "zarlacz srebrnopletwy" is Polish.[1]

Human interaction[change | change source]

Silvertip sharks are quite dangerous and according to the International Shark Attack File (ISAF) there have been 4 provoked attacks by this species on humans, with no deaths. Silvertips are caught by commercial and artisan fisheries across their range using longlines, gillnets, and trawls, both intentionally and as bycatch. Their fins are highly valued for shark-fin soup and are sold on the export market, along with their skin and cartilage. This species is vulnerable to overfishing (like almost all sharks) due to its slow reproductive rate. The IUCN has listed the Silvertip shark as Near Threatened, and has noted that it may be approaching the criteria for Vulnerable. This Silvertip shark is caught by fisheries in Indonesia, Myanmar and the Philippines. In the Philippines, it is in the top ten most caught species by number (0.73%), and weight (2.6%), with individuals ranging in size from 2.1-2.4 metres, and averaging 23 kg in weight. [2]

References[change | change source]