THE EDGE OF EXTINCTION; THE BLUE WHALE TRAGEDY

 Blue Whales evolved from the Indohyus, about 50 million years ago. The closest relative today is the hippopotamus. Up until the early 20^th century their numbers would have been fairly stable. The largest population was in the Antarctic, numbering approximately 240,000 (range 202,000 to 311,000).

With the advent of ‘mechanized’ whaling, they were hunted almost to extinction until protected by the international community in 1966. A 2002 report estimated there were only 5,000 to 12,000 Blue Whales worldwide.

Blue Whales tend to live alone or with one other individual but it is not known how long these associations last. Larger feeding groups of 30-50 may form when food is abundant but there does not seem to be the communication typical of a true pod. 

Blue Whale hunting was banned in 1966 but continued illegally in the USSR until the 1970’s. By that time 330,000 Blue Whales had been killed in the Antarctic, 33,000 in the rest of the Southern Hemisphere, 8,200 in the North Pacific, and 7,000 in the North Atlantic. By the time the killing stopped, only about 1 out of every 1000 Blue Whales (0.15%) survived.

Ships carrying whalers are no longer a threat to the Blue Whale but ships carrying cargo are. This summer four were run down by ships further depleting a population that is on the edge of extinction. Ship collisions result from whales and cargo using the same sea lanes for their journeys.

Whale migration:

Blue Whales do a lot of traveling and to better understand how their migrations conflict with shipping, a new generation of scientists is taking to the seas.

Today’s ‘hunters’ attach GPS tags to the Blue Whales to track their positions and record data as they travel. The high-tech devices are attached to the whale in the form of a small harpoon that is imbedded in the blubber.

The GPS tag will only transmit its data above the water when the whale surfaces to take another breath. They spend only about 10% of their time at the surface when they expel a rush of air and spray that can be seen two km away; there she blows!

National Geographic photo used for educational purposes.

Interested in swimming with dolphins? Check out some of the other posts in this blog.


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The Origin of Whales and Dolphins

Whales and dolphins belong to a group of animals called cetaceans. All cetaceans live in water today but their ancestors were land animals. 

The closest relative to today’s cetaceans is the hippopotamus. Whale ancestors left the land about 50 million years ago and became the baleen whales (plankton feeding) and toothed whales (fish and squid eaters) of today.

Humpback Whales

What did the early whales look like and how did they live?

The first fossils were found in the United States and were so different from modern whales that they were described as a reptile (dinosaur). Because of their size, they were named Basilosaurus, or king lizard. Many fossils were found with an average length of 18 metres and scientists believed that they may have reached 45 metres. Fossils have been found in Pakistan and Egypt and may have given rise to early worship of crocodile-like gods.

They were so different from modern whales that they were described as a reptile (dinosaur).

But they weren’t lizards!

We now know that the fossil Basilosaurus was a whale that probably hunted in shallow seas between 34 and 40 million years ago. It was about 18 metres long and the biggest animal on Earth at that time.

It had small paddle like hind fins that were left over (vestigial) from what were once legs. They were so small that the Basilosaurus probably swam more like a snake than a modern whale.

We can be very certain (look at the teeth) that Basilosaurus was an aggressive and dangerous predator. Careful examination of the skeleton suggests that Basilosaurus may not have been a long distance swimmer and probably could not dive to great depths. Its head and teeth are reminiscent of a crocodile’s and it may have hunted in a similar way; surprise attacks in shallow water or swimming down unfortunate prey.

Another 30 million years of evolution finds us sharing the planet with 81 species of whales from the metre long Hector’s dolphin to the Blue Whale, the largest animal to have ever lived on Earth.

Blue Whale and its calf

Killer whales in a pod.

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