The coelacanth
GS PAPER II: Conservation, environmental pollution and degradation, environmental impact assessment.
Context: The coelacanth — a wondrous fish that was thought to have gone extinct along with the dinosaurs 66 million years ago before unexpectedly being found alive and well in 1938 off South Africa's east coast.
The coelacanth
- These large and nocturnal deep-sea denizens shows that they boast a lifespan about five times longer than previously believed — roughly a century — and that females carry their young for five years, the longest-known gestation period of any animal.
- It develops and grows at among the slowest pace of any fish and does not reach sexual maturity until about age 55.
- Coelacanths first appeared during the Devonian Period roughly 400 million years ago, about 170 million years before the dinosaurs.
- Based on the fossil record, they were thought to have vanished during the mass extinction that wiped out about three-quarters of Earth's species following an asteroid strike at the end of the Cretaceous Period.
- After being found alive, the coelacanth was dubbed a "living fossil”.
- It is called a lobe-finned fish based on the shape of its fins, which differ structurally from other fish.
- Such fins are thought to have paved the way for the limbs of the first land vertebrates to evolve.
- Coelacanths reside at ocean depths of as much as half a mile (800 meters). During daylight hours they stay in volcanic caves alone or in small groups.
- Females are somewhat larger than males, reaching about seven feet (two meters) long and weighing 240 pounds (110 kg).
- The two extant species, both endangered, are the African coelacanth, found mainly near the Comoro Islands off the continent's east coast, and the Indonesian coelacanth.
- The researchers said late sexual maturity and a lengthy gestation period, combined with low fecundity and a small population size, makes coelacanths particularly sensitive to natural or human-caused environmental disturbances such as extreme climate events or too much accidental fishing.
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