Tag Archives: Gray Whales

Baleen Whales

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Baleen whales are in the suborder Mysticeti. They differ from toothed whales in a number of ways. All mysticetes have two nostrils or blowholes, while toothed whales (odontocetes) have only one blowhole. Mysticetes have a symmetrical skull, while most odontocetes have assymetrical skulls. Most toothed whales have a specialized echolocation system that is lacking in baleen whales. Female mysticetes are usually larger than their male counterparts, but other than that, there is no sexual dimorphism, while there is often marked sexual dimorphism in odontocete species. The most obvious difference between these two suborders, though, is that instead of teeth, mysticetes have baleen made from keratin, the same substance that comprises hair and fingernails. Stiff plates of baleen grow down from the gum of the upper jaws, and depending on the species, the baleen may be black, gray, creamy yellow, white, or a mixture of these colors. The outer edge of each plate is smooth, and the inner edge is frayed. The frayed inner edges intertwine to form a mat, allowing whales to filter feed and trap zooplankton and small fish in their baleen. Like hair and fingernails, baleen continues to grow at its base and wear along the edges.DSC_0670

All baleen whales are carnivorous, and most eat zooplankton or small schooling fish.  Most mysticetes employ one of two different systems for feeding, and some species use both systems, depending on the situation and prey density. These systems can be described as “skimming” and “gulping.” Skimming is when a whale swims open-mouthed through a food supply, while gulping, as its name implies, is achieved when a whale swims through a food swarm and gulps large amounts of water and food by extending the ventral grooves in its throat to greatly enlarge the size of its mouth, depressing its tongue, and opening its lower jaw to a nearly 90 degree angle from the body axis. After engulfing the prey, the whale closes its mouth and forces the excess water out through the baleen. It then uses its tongue to transfer the prey to its gullet, and from there, it passes into the stomach. Gray whales, which are mainly bottom feeders, have their own unique style of feeding. Most baleen whales feed for only four months during the summer, and they must consume enough food during this time to sustain them for the rest of the year. It has been calculated that a baleen whale consumes 4% of its body weight per day during the summer feeding season.

Baleen whales are some of the largest animals on earth. In fact, blue whales are the largest animals to have ever inhabited the planet. The buoyancy of water supports a whale’s body, allowing it to grow to a greater size than it could if it lived on land. This large size has several advantages. The decreased surface to body-volume ratio helps a whale conserve heat. The large body size also makes a whale safer from predators, and it allows a whale to eat large quantities of food when food is available and then store this energy in the form of blubber that can be broken down for energy during periods of fasting.

The general body shape of most baleen whales is cylindrical, tapering at the ends. This shape is energy-efficient for swimming and creates less drag. A whale’s skin is smooth and has no oil glands or pores. Many species of mysticetes have sparse hairs on the snout, jaws, and chin, but the lack of hair or fur on the body is an adaptation to reduce drag when swimming.

DSC_0650A baleen whale has a small, external ear opening on each side of its head that leads to an auditory canal. The middle and inner ear is similar to that of other mammalian species, but the ears are adapted for hearing under water.

Baleen whales produce low-frequency sounds, mostly below 5000 Hz. These are some of the loudest sounds produced by any animal, and the sounds travel hundreds of kilometers under water. Scientists think these loud sounds may be used for long-range contact, advertising for a mate, greeting, orientation, navigation, or announcing a threat. The sounds consist of very-low frequency moans, grunts, thumps, and knocks and higher frequency chirps, cries, whistles, and songs.

Some baleen whales can swim as fast as 20 mph (32 kph). They swim by using powerful up-and-down strokes with their tails to push their streamlined bodies through the water. While some mysticetes can dive to depths over 1000 ft (355 m), most species feed at relatively shallow depths. A whale holds its breath when under water, and when it surfaces, it opens its blowholes and blasts a loud exhalation. The whale then quickly inhales and closes its blowholes before diving. Most baleen whales surface and breathe several times before diving. The spout of water that is often the first visual clue of a whale’s presence, does not come from the whale’s lungs. As with other mammals, a whale’s lungs do not tolerate water. Instead, the water spout is produced from water that was on top of the blowhole when the whale exhaled, and the water condenses as the respiratory gases expand in the air. The size and shape of a whale’s “blow” varies from species to species.

Mysticetes can be found in all oceans. They live in polar, tropical and temperate zones. There are three families in the suborder Mysticeti. These are Balaenopteridae, or the Rorqual Whales; Balaenidae, the Right Whales; and Eschrichtidae, the Gray Whale. In my next few blogs, in the family Balaenopteridae, I will cover the blue whale, the fin whale, the sei whale, the Minke whale, and the humpback whale. In the family Eschrichtidae, I will cover the gray whale.

While I see these whales on their summer feeding grounds, I know many of you have watched whales in their winter breeding areas, perhaps in Mexico or Hawaii. Please share your experiences!

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Whales

Fin whales in Uyak Bay
Fin whales in Uyak Bay

Whales have been on my mind lately; probably because I’ve seen some nearly every time I’ve gone for a boat ride this summer and fall. Zooplankton and schools of small fish have swarmed the bay all summer and fall, providing abundant food for everything from larger fish, gulls, eagles, other birds, harbor seals, sea lions, and of course whales. I’m certain that if I jumped in my boat right now, within in minutes, I’d be in the midst of several huge fin whales, whose 18-ft. tall exhalations surpass any choreographed water-fountain show in Las Vegas. I’d probably also see two or three humpbacks waving their tail flukes in the air and perhaps leaping out of the ocean and slapping their large pectoral fins and tail flukes on the water.

I’ve also been thinking about whales, because that is the chapter I’m working on for my book on the wildlife of Kodiak Island. While I love whales, writing about them has been an arduous process, since little is known about many species, and I must draw bits and pieces of information from an array of sources. This painstaking research, though, has provided me with a better understanding of these huge, intelligent creatures, so I thought I would write a few posts about them. I will focus on the whales that can be seen near Kodiak Island, and I will admit that I have not seen all these species, because either they migrate past the island and do not enter the deep bays, or they spend their lives off shore. There is also another, darker reason for me to write about the whales near Kodiak Island. This summer more than 30 whales (mostly fin and humpback) died near Kodiak, and biologists are scrambling to discover the cause.

Whale species commonly found near Kodiak include fin whales, the second largest species of whale; sei whales, the third largest species of whale; humpbacks; Minke whales; and Orcas, or killer whales (although Orcas are actually dolphins, not whales). Gray whales migrate past Kodiak on the way from their breeding and birthing areas near Mexico to their northern feeding grounds, and blue whales, the largest species of whale, can be found off shore in the Gulf of Alaska. Blue whales, fins, sei whales, humpbacks, Minkes, and gray whales are all filter feeders and have baleen instead of teeth. Killer whales, of course, have teeth.

As you probably know, whales, like humans, are mammals. They have lungs and must breathe air to survive. They are warm-blooded, and like most mammals, they bear live young. Whales nurse their young with milk, and while you may not think of a whale having hair, all whales do have hair at some stage in their development. Whales are in the order Cetacea, and all members of this order are believed to have evolved from hoofed animals, such as cows, sheep, and camels, 45 million years ago.

All cetaceans have forelimbs that have been modified into flippers and no hind limbs. Their tails are horizontally flattened, and they breathe through a nostril or blowhole, located on the top of the head. Whales have internal sensory and reproductive organs to reduce drag when swimming, and cetacean mothers nurse their calves with a pair of teats that are concealed in slits along the body wall.

Cetaceans living in the cold ocean waters of the North Pacific must somehow maintain a body temperature that is nearly the same as a human’s body temperature, and a whale uses a number of mechanisms to accomplish this feat. First of all, it has a thick layer of blubber which has few blood vessels, reducing heat loss at the body surface. A whale has a counter-current exchanger, where veins at the periphery are surrounded by arteries. Heat lost by vessels flowing from the warmer core toward the cold periphery is at least partially absorbed by vessels flowing from the periphery to the core. A cetacean also has a fairly high metabolic rate to produce heat, and it has a low body surface to volume ratio, which conserves heat. Also, a whale breathes at a slower rate than a land mammal does, so warm air is expelled less frequently.

The order Cetacea is divided into two suborders: The Mysticeti or baleen whales and the Odontoceti, or toothed whales. I primarily will be discussing the Mysticetes, and next week, I’ll describe baleen and how it is used. Please leave a comment if you have any questions or would like to add anything about whales. I would love to hear about your whale experiences!

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Subscribe to my monthly e-mail mystery newsletter. Beginning in late November, I will begin chronicling some true-life Alaskan crimes!

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