Common names
Seidenhai, Cazon, Cazon de playa, Cazón-tiburón, Jaqueta, Jaqueton, Tiburon jaqueton, Tiburón, Tiburón lustroso, Tiburón piloto, Tiburón sedoso, Tinterero, Tollo, Tollo mantequero, Mangeur d"hommes, Requin soyeux, Blackspot shark, Grey whaler shark, Olive shark, Reef shark, Ridgeback shark, Shark, Sickle shark, Sickle silk shark, Sickle-shaped shark, Silk shark, Silky shark, Silky whaler, Cação, Lombo preto, Marracho sedoso, Marracho-luzidio, Tubarão-luzidio

Short Description
Diagnose after Compagno,1984 [517]: Field Marks : A large, dark, slim, oceanic grey shark with moderately long rounded snout, moderately large eyes, oblique-cusped serrated teeth in the upper jaw, upper teeth with basal cusplets or very strong serrations, usually 15/15 rows of anteroposterior teeth, an interdorsal ridge, long narrow pectoral fins, a moderatesized first dorsal with its origin behind the pectoral rear tips, a low second dorsal with a greatly elongated inner margin and rear tips, and no conspicuous markings. Diagnostic Features : A large, fairly slender species (up to about 3.3 m). Snout moderately long and rounded; internarial width 1.2 to 1.6 times in preoral length; eyes circular and moderately large, their length 1.2 to 2.7% of total length; upper labial furrows short and inconspicuous; hyomandibular line of pores just behind mouth corners not conspicuously enlarged; gill slits moderate-sized, the third 2.9 to 3.6% of total length and less than 2/5 of first dorsal base; usually 15/15 rows of anteroposterior teeth in each jaw half but varying from 14 to 16/13 to 17; upper teeth with fairly narrow, strongly serrated, erect to moderately oblique cusps, welldelimited from crown feet, feet with heavy serrations or small cusplets; lower teeth with erect, narrow, smoothedged cusps and transverse roots. A narrow interdorsal ridge present. First dorsal fin moderate-sized and falcate, with narrowly to broadly rounded apex and posterior margin curving ventrally from fin apex; origin of first dorsal fin behind pectoral free rear tips; inner margin of first dorsal long, about half dorsal base or slightly more or less; second dorsal fin very small and low, its height 1.3 to 2.2% of total length, its inner margin long and 1.6 to 3 (usually over 2) times its height; origin of second dorsal over or slightly behind anal origin; pectoral fins large (especially in adults, shorter in young), narrowly falcate, with narrowly rounded or pointed apices, length of anterior margins about 14 to 22% of total length; 199 to 215 total vertebral centra, 98 to 106 precaudal centra. Colour dark grey or grey brown above, sometimes nearly blackish, white below; tips of fins other than first dorsal dusky but not black-tipped; an inconspicuous white band on flank.

Distribution
Circumtropical. Western Atlantic: Massachusetts, USA to southern Brazil, including the Gulf of Mexico and the Caribbean Sea to Uruguay [5839]. Eastern Atlantic: Spain, Madeira to northern Angola; St. Paul"quot;s Rocks [5002]; Cape Verde [20238]. Indo-Pacific: scattered records from the Red Sea and Natal, South Africa [536] to China, New Zealand, and the Caroline, Hawaiian, Phoenix and Line islands. Eastern Pacific: southern Baja California, Mexico to northern Chile. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea [20076]. First record: 1997: Seto Inland Sea, Japan [12421]; 2012: Ligurian Sea, Northwestern Mediterranean [16151]; 2019: New Ireland Province, Papua New Guinea, western Pacific Ocean [27359]; Source: www.gbif.org

Human uses
fisheries: highly commercial; price category: high; price reliability: reliable: based on ex-vessel price for this species

Biology
Viviparous, placental [733]. 2-15 pups [1388] (Ref. 37816) born at 57-87 cm TL [544]; 1-16 pups born at 55-72 cm TL. Females appear to breed every year, but there appears to be no reproductive seasonality [2539]. Distinct pairing with embrace [17086]. Often found over deepwater reefs and near insular slopes. When approached by divers, individuals have been seen to perform a "quot;hunch display"quot;, with back arched, head raised and caudal fin lowered, possibly as a defensive threat display. Associated with schools of tuna, causing damage to nets and catches. Referred to as the `net-eater shark"quot; in the tropical eastern Pacific[17641]
Diet: Ecuadorian Pacific [25131]: (data basis: 69 (43 female, 26 males) stomachs analysed, 10 stomach empty, TL 95 cm - 310 cm total length). The authors were able to identify 19 dietary components to the lowest taxon: 12 teleosts and eight cephalopods, as well as the remains of fishes, cephalopods and turtles. Based on the %IRI, teleosts contributed most to the C. falciformis diet. The most important prey were the Scombridae fishes Thunnus albacares (%IRI ¼ 22.4%), Thunnus sp. (12.9%) and Auxis thazard (4.77%). The trophic spectrum of both females and males consisted of teleosts and cephalopods; females also consumed turtles. The most important prey species for males were the cephalopods Ancistrocheirus lesueurii (13.2%) and Vitreledonella richardi (8.8%), while females preferred the fishes T. albacares (29.7%), Thunnus sp. (12.0%) and A. thazard (5.88%)

Size / Weight / Age
350 cm TL (male/unsexed; [544]); max. published weight: 346.0 kg (Ref. 40637); max. reported age: 25 years [2246]

Habitat
reef-associated; oceanodromous [17660]; marine; depth range 0 - 4000 m (Ref. 55180), usually 0 - 500 m [1388]

Remarks
shark-references Species-ID=749; CITES: (see: Protected Species for more details) Convention on International Trade in Endangered Speciesof Wild Fauna and Flora annex: II; Council Regulation 2017/160 annex: B

Parasites (arranged by Jürgen Pollerspöck)
Cestoda

• Dasyrhynchus variouncinatus (Pintner, 1913) [5977] [16112]
• Tentacularia coryphaenae Bosc, 1797 [21816] [32432]

Trematoda

• Botulus microporus (Monticelli, 1889) [17647]
• Staphylorchis cymatodes (Johnston, 1913) [11242]

Copepoda

• Alebion carchariae Krøyer, 1863 [19356] [19355]
• Echthrogaleus denticulatus Smith, 1873 [16599]
• Kroyeria carchariaeglauci Hesse, 1878 [17867]
• Kroyerina cortezensis Deets, 1987 [15948]
• Pandarus cranchii Leach, 1819 [16599] [16583] [16599] [16599] [19356] [19355]
• Pandarus katoi Cressey, 1967 [16599]
• Pandarus smithii Rathbun, 1886 [16583] [16599]

Isopoda

• Gnathia trimaculata Coetzee, Smit, Grutter & Davies, 2009 [21224]

Hirudinea

• Pontobdella macrothela (Schimarda, 1861) [17101] [25687]