Thresher Shark

Fascinating facts about the Thresher Shark

• A single common thresher can grow as long as a school bus, reaching a confirmed 5.7 m (19 ft) and possibly up to 6.5 m (21 ft). Its massive upper tail lobe makes up about half its total length, so a 6 m shark carries a 3 m blade-like fin that it whips like a coach-whip to stun schools of anchovies and sardines.
• A common thresher's body runs hotter than the surrounding ocean: red muscle tissue averages 2 °C (3.6 °F) above ambient water thanks to a counter-current "rete mirabile" that conserves metabolic heat. This internal furnace lets the shark cruise at temperatures within its preferred range of 16-21 °C (61-70 °F).
• Females give birth to only four pups after a nine-month gestation, and each embryo feeds on undeveloped eggs the mother ovulates, a strategy called oophagy. With litters of just two to four, the species cannot replace numbers lost to longline and gillnet fisheries, which took 411 metric tons worldwide in 2006 and caused a rapid collapse of the California fishery in the 1980s.
• Tagging studies off southern California show common threshers spend most of their day within 40 m (130 ft) of the surface, diving deeper only briefly to around 100 m (330 ft). This surface-dwelling habit matches their hunting technique of herding schools with tail-splashes, and explains why they are most abundant within 30 km (20 mi) of coastlines where prey congregate.
• The common thresher's weight can top 510 kg (1,120 lb), a 4.8 m (16 ft) female recorded at that mass, and some unverified reports suggest individuals may reach 900 kg (2,000 lb). Such bulk, combined with a streamlined torpedo body, makes it a prized game fish; anglers rate its fight as "exceedingly stubborn" and comparable to the short-fin mako, underscoring its importance to recreational fisheries.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia

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