Another shark with a name leaving no doubt about the reason is the Finetooth shark (Carcharhinus isodon). Named after its nearly even, rather slender teeth in upper and lower jaw (isodon means „even tooth“), its name is also Eventooth Shark or Smoothtooth Shark, in German Feinzahnhai, in French Requin à Petites Dents and in Spanish Galana Dientefino or Tiburón Dentiliso (however, I don’t know why it is also named Night Shark or Tiburón de Noche).

Carcharhinus isodon in net.JPG
Von National Observer Program, NMFS/SEFSC – http://www.st.nmfs.noaa.gov/observer-home/about-nop/activities/index, Gemeinfrei, Link

The Finetooth shark inhabits extremely shallow coastal waters (no deeper than 33 ft -10 m- in the summer and 66 ft -20 m- deep in the winter) in the Northwest Atlantic, Gulf of Mexico and Southwest Atlantic (off Brazil) in distinct populations. In the past it was known to venture into rivers, though most of its paths are nowadays blocked by dams. That’s a problem, since the females move to special inshore nursery areas. There they give birth to 2 to 6 living, 19 to 25 in -48 to 64 cm- long young every 2 years after a 12 month gestation period. Like all species of the family requiem sharks, finetooth sharks are oviviparous, that means the embryo hatches in the womb and is born alive. Additionally, the depleted yolk sac develops into a placental connection to the mother after the embryos drain their yolk supply during their first 15 weeks (viviparous).

Although having a maximum length of 6.2 ft -1.9 m- (on average males reach only 5.2 ft -1.6 m- in length and females 5.4 ft -1.7 m-), the finetooth shark is no danger to humans. However, it thrashes and snaps at anything within reach when caught. It matures at 40 in -1 m- (at 4-5 years as males and 5-6 years as females, who are growing slower in general) and has a life span of 9 years – males- or 14 years – females.

Off the coast of North America the finetooth shark is known to migrate south seasonally (namely when surface water temperatures drop below 68°F -20°C-). It hunts in large schools for small fish. It is susceptible to habitat degradation (especially it nursery areas) and overfishing (as bycatch and targeted), but is considered (despite its low reproductive rate) as Least Concern – at least in the northern hemisphere, off Brazil however there is only a badly managed fishery which already pushed other shark species near extinction.

Sources: here, here and here

 

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