Silky Shark(Carcharhinus falciformis)

(Bibron, 1839).
|
Fr: | Requin soyeux |
|
Sp: | Tiburon jaqueton |
|
It: | N/A |
|
Ma: | N/A |
Diagnosis
A large, somewhat slender shark with a moderately long and slightly
pointed snout; narrow interdorsal ridge.Ê Eyes round and quite large.Ê
First dorsal fin small (height ca. 5.2-10% of TL) with a curved apex,
origin posterior to the rear corner of the pectoral fins; second dorsal
fin noticeably small and low, with its origin slightly ahead of the anal
fin, and a long free rear tip over twice as long as the fin height.Ê
Pectoral fins quite large but slender, with their anterior margins
measuring ca. 14.2 to 22% of TL and narrowly-rounded or pointed apices.Ê
Upper-teeth essentially triangular, becoming more oblique rearwards,
strongly serrated and deep indentations on the rearward edges; crown
feet with coarser serrations.Ê Colour dark bronzy-grey or mid-grey
dorsally, fading to white ventrally with a poorly-defined white band on
the belly-flanks; fin-tips (with exception of 1st dorsal) rather dusky.
Size
To 330 cm TL; usually to 300 cm;Ê size at birth ca. 70 to 87 cm.
Status and Distribution
Mediterranean Sea:
Rare or occasional; apparently as an Atlantric vagrant into the Western
Mediterranean, where it occurs in the zone from Gibraltar immediately
eastwards.Ê Infrequently taken at Gulf of Chafarinas (Morocco) and
neighbouring sites (to Algeria?); possibly more cosmopolitan, at least
in the Alboran Sea, than current records infer (preserved jaws of this
species examined by I.K. Fergusson at Favignana, Sicily).Ê Not yet
definitively recorded from Sicilian Channel but a likely addition, given
the presence of other oceanic Atlantic vagrants such as C. obscurusÊ and
Alopias superciliosus, and quite likely to be recorded throughout the
deeper, warmer zones of the Mediterranean basins.
Biology
Poorly-known within the Mediterranean.Ê An epipelagic or semipelagic,
oceanic and littoral shark found in warm-temperate and tropical seas
within the influence of land masses or islands, from the surface to at
least 500m; usually far from the coast over continental or insular
shelves; also at offshore banks, but sometimes occurring nearer to shore
over deep blue waters and even over depths as little as 18 m.Ê This
species is apparently more prone to making inshore excursions than its
pelagic relatives, Carcharhinus longimanusÊand Prionace glauca, and may
be less well adapted to a truly oceanic lifestyle.Ê Silky sharks are
active, fast-moving predatorsÊ of a variety of bony fish, including
tunas (with which they are commonly associated) and other scombroids;
also mullet and other coastal species; squid, pelagic crabs and octopi.Ê
Segregation by size occurs, with younger sharks nearer to shore.ÊÊ In
the Western Atlantic, pupping-zones occur over depths of 80-100 m.Ê
Litter size is 2 to 14 pups (average litter varies geographically), with
no defined breeding-season.Ê Males mature at 187-217 cm,Ê females at
213-230 cm.
|