You are currently browsing the tag archive for the ‘whales’ tag.

Adult female Cuvier's beaked whale (Ziphius cavirostris). Photo by Robin Baird.

Adult female Cuvier’s beaked whale (Ziphius cavirostris). Photo by Robin Baird.

There are entire species of large mammals living today on Earth which have never been seen alive by humans.  Even though they can grow larger than elephants, their numbers and habits are unknown.  We might not even know all extant species in the family.  These mystery mammals are the beaked whales (family Ziphiidae) masters of deep ocean diving.  The family is comprised of at least 21 different species, only 3 of which are well known (thanks to whale hunting in previous centuries). Beaked whales are poorly understood because they are rarely on the surface of the ocean where we can observe them.  They are capable of diving more than 1,899 meters (6,230 feet) and can stay underwater for almost an hour and a half.  Beaked whales live in the black–down among the underwater seamounts, canyons, and abyssal plains.  We only know them from the examination of dead specimens: indeed, for some species of beaked whales that is quite literally true and they have only been seen when dead.

Small Beaked Whales (an illustration by Brett Jarrett)

Small Beaked Whales (an illustration by Brett Jarrett)

Beaked whales grow to sizes of 4 to 13 metres (13 to 43 ft) depending on the species.  They are sexually dimorphic—the males are a different size than the females.  Additionally male whales have prominent domed foreheads and a pair of fighting teeth for dueling and sexual display (these teeth do not fully develop in females).  Beaked whales feed on squid, and, to a lesser extent, fishes and invertebrates which they capture from the ocean bottom by means of suction.  In order to produce this suction effect, the whales have highly nimble tongues and throat grooves.

The most distinctive features of beaked whales (save perhaps from their rostral “beaks”) are the body features which allow them to dive so deeply and then hunt in the dark crushing waters.   The lungs of beaked whales collapse at a certain pressure—most likely as a way to minimize the dangers of nitrogen transfer. Their livers and spleens are huge in order to deal with the dangerous metabolic bi-products of prolonged periods when they are unable to breathe.  Additionally, their blood and muscle tissue is capable of capturing and storing substantially greater quantities of oxygen than the tissue of other mammals.  Beaked whales can pull their pectoral flippers into grooves which run along the sides of their bodies and thus become more streamlined.

Sowerby's Beaked Whale (Mesoplodon bidens)

Sowerby’s Beaked Whale (Mesoplodon bidens)

In order to find their way in the deep ocean, the whales rely on sophisticated acoustic echo-location organs.  Lips behind the blowhole produce high pitched vibrations which bounce off of prey and obstacles.  Echoes from these vibrations are then picked up and focused into the whales’ sensory organs by special fat deposits and bone structures.   Unfortunately this method of echolocation seems to make beaked whales extremely sensitive to sonar.  Resurfacing whales are unable to avoid the amplified sound waves and can suffer injuries to their sensory organs (or even to their large delicate livers).  Additionally, it is theorized that Beaked whales may try to resurface too quickly to avoid sonar and therefore risk decompression sickness.

(Photo: credit Nan Hauser & Hoyt Peckham, CCRC)

(Photo: credit Nan Hauser & Hoyt Peckham, CCRC)

Humankind has also been fishing ever deeper waters as fish stocks crash—which involves the whales in by-catch issues.  Hopefully we will learn more about this family of enigmatic divers (and become more responsible stewards of the ocean) so that the beaked whales do not vanish before we even get to know them.

Sowerby's Beaked Whale original 2

Wadi Al-Hitan, Egypt

In the desolate desert 150 kilometers southwest of Cairo there is a fearsome arid valley (wadi) of cliffs, carved buttes, and sandblasted erratic boulders.  The bleached landscape has an otherworldly emptiness as though it were located on a lifeless alien planet, though if you look closely, the desert is filled with austere furtive life like dorcas gazelles, tiny sand colored lizards, cobras, scorpions, and fennec foxes. The name of the place is even more otherworldly—“Wadi Al-Hitan” which is Arabic for “valley of the whales” and although the great smooth rocks buckling out of the sand might momentarily be taken for the backs of huge whales, the utter absence of the ocean (or of water of any kind) makes the name seem fanciful. The nearby Mount Garet Gohannam (which means mountain of hell because of the way it glows like flames at sunset) seems to be more aptly named.

Whale fossil at Wadi Al-Hitan

However the name of Wadi Al-Hitan is remarkably literal–for the valley contains the remains of hundreds of huge ancient cetaceans which died in the Eocene and were fossilized in the yellowish sandstone.  Forty million years ago the valley was a marine lagoon.  Although the remains of numerous sirenians, sawfish, sharks, rays, sea turtles, marine crocodiles, sea snakes, and even swamp dwelling moeritheriums have been discovered in the wadi, the valley takes its name from the most spectacular and numerous fossils which belong to four different species of primitive whales.  The most commonly discovered fossils belong to Dorudon, which was 3-5 meters long (9-15 feet) and fed on fish and mollusks, and to Basilosaurus, which was 15-22 meter (50-72 foot) and fed on everything else in the ocean.

Basilosaurus was first discovered in Louisiana in the early 19th century.  Its immense size and serpentine form initially convinced naturalists that it was a marine reptile and they misnamed the creature Basilosaurus (which means “king lizard”).  The mistake soon became obvious and Basilosaurus was classified among the Archaeoceti, a paraphyletic suborder of the cetaceans, however the giant kept its dinosaur name.  Different species of Basilosaurus flourished in oceans worldwide during the wet, tropical Eocene and, even though they were obviously very adept at ocean living (indeed rising to the top of the food chain) the creatures betray vestiges of terrestrial living which modern whales have entirely dispensed with. Not only do Basilosaurus fossils have teeth and jaws which retain reatures from their artiodactyl ancestors, they also have tiny vestigial back legs a mere half meter in length (which would scarely help a 22 meter animal get around).  Additionally Basilosaurus was different from modern whales in that it probably moved with eel-like horizontal thrashing of its long tail (modern whales move their flukes vertically).  Basilosaurus probably did not dive very deeply, but moved about near the surface of the oceans hunting for smaller marine animals.

Basilosaurus from “Life in the Ancient Seas Exhibit” at the Smithsonian Institution, National Museum of Natural History

Although Wadi Al-Hitan was discovered by Europeans in 1902-1903, some archaeologists and anthropologists have speculated that it was known long before that and have been irresistibly drawn towards comparing basilosaurus with the giant crocodiles and earth spanning serpent gods which populate ancient Egyptian cosmology.

Detail from painting (Life in the Ancient Seas Exhibit: Smithsonian Institution, National Museum of Natural History)

Ye Olde Ferrebeekeeper Archives

July 2019
« Jun