Monthly Archives: November 2015

Gray Whales

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Gray whales are one of the most-researched and best-understood species of whales. They are baleen whales, but unlike the whale species I’ve discussed the past two weeks, they are not rorquals in the family Balaenopteridae. Gray whales are the only species in the family Eschrichtiidae. You may recall that I mentioned that rorquals all have two characteristics in common: numerous ventral throat grooves and a dorsal fin. Gray whales do not have a dorsal fin, and they only have two to four throat grooves. They also differ from rorquals in several other ways. A gray whale has the coarsest baleen of any whale and the fewest number of baleen plates. Unlike rorquals, gray whales are predominantly suction, bottom feeders. A gray whale scrapes the side of its head along the ocean floor and scoops up sediment with its mouth, capturing small invertebrates in its baleen while expelling the sediment through the baleen fringes. Amphipods are the favorite food of gray whales. Gray whales are also stockier than most rorquals and are slower swimmers. They migrate close to shore, making them easy to watch and study.

The gray whale is one of the most ancient species of mammals, and it is estimated to have been on earth for approximately 30 million years. As the name suggests, gray whales are slate gray in color with gray and white patches on the skin. They are covered with abrasions, scars, and clusters of barnacles and whale lice, and they sometimes carry over 400 lbs. of barnacles and lice. Adults average approximately 46 ft. (14 m) in length, with females slightly larger than males. The average weight is 30 to 40 tons. A gray whale’s body is streamlined, and it has no dorsal fin but does have a dorsal hump about 2/3 of the way down the back. This hump is followed by 6 to 12 knobs extending to the tail stock. It has a narrow, triangular head that is arched downward when viewed from the side.

Gray whales have one of the longest migrations of any mammal. In the summer they feed in the arctic in the Bering, Chukchi, and Beaufort Seas, and in the fall they migrate to their calving grounds in the southern Gulf of California and Baja Mexico, a migration of 5000 to 7000 miles (8,050 – 11,275 km) each way. Their average swimming speed is only 3 to 5 mph (5-8 km/hr), so this migration takes a long time. On their northern migration, they pass by Kodiak Island in April and May, where they can be viewed from bluffs along the outside perimeter of the island. They are travelling and rarely stop to explore the deep bays on the island, and unfortunately, I have never witnessed their migration, which explains why I have no photos to accompany this post. The gray whales’ migration is considered a rite of spring on Kodiak, and is celebrated with a 10-day Kodiak Whale Fest with many activities, including guided trips to good whale-watching spots.

There are currently two gray whale populations, but at one time, there were three. The north Atlantic population is thought to have become extinct in the 17th century from over hunting. The Pacific gray whales were nearly wiped out in the 1850’s after the discovery of the calving lagoons in Mexico, but were partially protected in 1937 and completely protected in 1947, and since then, the eastern north Pacific population has made an incredible recovery and is now close to the original population size. The western Pacific stock, however, is endangered and is estimated to have only 101 individuals.

Gray whales have been impacted by ocean warming in recent years. Increasing sea water temperatures in the Bering Sea have reduced winter ice cover in the region, which has led to a reduction in productivity. Primary productivity in the northern Bering Sea declined 70% from 1988 to 2004, and the previously ice-dominated, shallow ecosystem that favored large communities of benthic amphipods (the favorite food of gray whales) has been replaced by an ecosystem dominated by pelagic fish. Gray whales have responded by migrating further north to the Chukchi Sea, but it is not certain what will happen if amphipod communities disappear from this region.

If you’ve spent time around gray whales, please leave a comment and tell me about your experience.  Also, if you are interested in reading sensational Alaskan true-crime stories, please sign up for my monthly Mystery Newsletter on my home page.

Humpback Whales

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Humpback Breaching
Humpback Breaching

Humpback whales are the best-known members of the family Balaenopteridae. Like other rorquals, humpbacks have a dorsal fin, and they have ventral throat grooves running from the tip of the lower jaw to the belly, but humpbacks differ in many ways from the other species in the family Balaenopteridae, and because of these differences, humpbacks are classified in a separate genus from the other rorquals. The body of a humpback is more robust and not as sleek as the bodies of fin, sei, blue, and minke whales. The top of the head and the lower jaw of a humpback are covered by rounded bumps, each containing at least one stiff hair, and the pectoral flippers are very long, spanning one-third of the body length. The tail stalk is thin, and the tail has a series of ridges on the trailing edge. Humpbacks are slower swimmers than other rorquals, but they are more acrobatic than their cousins. They often raise their tails high in the air before diving and engage in breaching, tail slapping, flipper slapping and other physical activities. It is this acrobatic behavior, their curiosity, and their beautiful, haunting songs that make them so popular with humans.Humpback2

Adult humpbacks average 49 ft. (15 m) in length and weigh approximately 35 tons. They are predominantly black on the dorsal side and have varying degrees of white on the throat, belly, flippers, and flukes. The shape and color pattern on a humpback’s dorsal fin

Photo by Tony Ross
Photo by Tony Ross

and flukes are unique to the individual, much like a human’s finger prints. Once biologists realized this, they were able to catalog and follow individual whales during their migrations and throughout their lives, greatly increasing our understanding of humpbacks’ social, mating, calving, and feeding behaviors, as well as giving researchers a better estimate of population sizes.

The baleen of a humpback is black in color, and like most other baleen whales, humpbacks feed in high latitudes and breed and give birth in low latitudes, near Mexico, Hawaii, and in the western Pacific near Japan. We mostly see humpbacks in the summer near Kodiak Island, but a few individuals spend the winter here as well. Since humpbacks don’t reach sexual maturity until they are 5 to 7 years old, it is possible that some whales we see in the winter are not yet sexually mature, so they do not migrate to breeding and birthing areas. Humpbacks feed on krill, other zooplankton, and small schooling fish. As with other baleen whales, humpbacks feed almost exclusively during the summer months and live off their fat reserves in the winter. It has been estimated that a humpback eats up to 1.5 tons of food per day when it is feeding. Humpbacks sometimes employ a method known as bubble net feeding, where they release air bubbles while swimming in circles beneath their prey and then lunge open-mouthed to the surface through the center of the concentrated prey.

Humpbacks are known for their acrobatic displays, including breaching, spy-hopping, lob-tailing, tail-slapping, and flipper slapping, and some of these displays can last for hours, especially during mating. In a few weeks, I will discuss these behavioral displays in more detail

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Humpbacks are also famous for their long, complex songs. These songs are sung by male humpbacks in the winter, and it is believed that their primary function is to attract females, although it has also been suggested that the songs may be used between two males in order to establish dominance. All whales in a particular population sing essentially the same song, and as the song changes slowly over time, the males somehow coordinate these changes. A typical song lasts 10 to 20 minutes, but it may be repeated continuously for hours. During mating, males compete very aggressively for females, and these competitions that sometimes last several hours may involve tail slashing, ramming, and head butting. Although humpback whales are quite social during the mating season, they are usually found alone or in small groups on their summer feeding grounds.

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Next week, I will post about gray whales, one of the most-researched and best-understood species of whales. As always, I welcome your comments, and would love to hear about some of your whale encounters.

For mystery lovers, please visit my home page and sign up for my monthly Mystery Newsletter. I will be sharing details of some true-life Alaskan crimes!

Family Balaenopteridae: The Rorqual Whales

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Members of the whale family Balaenopteridae are known as the Rorqual whales. “Rorqual” is a Norwegian term that means “furrow whale,” referring to the throat grooves found in all species in this family. These grooves extend from underneath the lower jaw back to at least the pectoral flippers and are folds of skin and blubber. When a rorqual feeds, it lunges forward at high-speed, and these grooves expand, filling the mouth with a huge amount of water and prey. When the whale closes its mouth, it uses its tongue to strain the water through the baleen plates, trapping small fish and zooplankton. In addition to throat grooves, the other characteristic common to all rorquals is a dorsal fin.

With the exception of the minke whale, all rorquals are very large, but they are also streamlined and capable of swimming at incredible speeds. Most of the whales in this group have similar body shapes and fin shapes and placements, sometimes making it difficult to distinguish one species from another. At a distance, a small blue whale looks much like a fin whale, and unless you are close enough to see the lower jaw, a small fin whale and a large sei are identical in appearance. Humpback whales with their long pectoral fins are usually easy to differentiate from other rorqual species, and minke whales are much smaller than any other species in the family Balaenopteridae. Rorquals have flattened heads and two, centrally-located blowholes. The dorsal fin is located approximately one-third of the body length forward from the fluke notch, and the tail flukes are large and wide.

In this post, I will briefly cover blue whales, fin whales, sei whales, and minke whales, and next week, my post will be about humpback whales. The reason why I’m dividing it up like this is that there is far more information about humpbacks than there is about the other species in this family. While it is known that most rorquals feed in high latitudes during the summer and breed and give birth during the winter in temperate or tropical latitudes, biologists do not know how far they migrate and what percentage of the population migrates. We see fin whales and even humpbacks all winter here on Kodiak Island, so it is clear that not all individuals migrate every year.

Blue whales are the largest animals to have ever lived on earth. Females may reach 90 ft. (28 m) in length. They are a mottled bluish gray and streamlined with a broad, rounded head, long, slim flippers, and a very small dorsal fin that is located so far back toward the flukes that it is usually only seen when they are about to begin a dive. They have broad, triangular flukes are only slightly notched, and their baleen is solid black. I have never seen a blue whale, because they are usually far off shore in deep water near the continental shelf. They are rarely seen in the bays around Kodiak Island, but in the summer, they can be found in the Gulf of Alaska and the Bering Sea. I think it is interesting that the largest animal on the planet dines on one of the smallest animals. Blue whales primarily eat euphausiids, small shrimp-like organisms that are commonly called krill.

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Fin whales are the second-largest species of whale. An average adult female fin whale is 73 ft. (22 m) in length, while an average male is 70 ft. (21 m). A fin whale’s upper jaw is V-shaped and flat on the top, and it has a distinct ridge on its back that extends from the dorsal fin to the tail fluke. Its dorsal fin is up to two feet tall and is curved with a steep backward angle and a blunt tip. The flukes are broad and triangular with pointed tips and a central notch. A fin whale has a light gray to brownish-black back and sides, with two lighter-colored chevrons that begin behind the blowholes and slant down the sides toward the fluke and then swirl up and end behind the eye. The undersides of the body, flippers, and fluke are white. The left lower jaw of a fin whale is dark gray, but the right lower jaw is white, and this asymmetrical coloration extends to the baleen plates. Scientists think this asymmetrical jaw color may somehow aid fin whales in capturing prey. If seen up close, the right lower jaw of a fin whale clearly distinguishes it from a blue or sei whale. Fin and blue whales produce the loudest biological sounds in the ocean, and recent research on fin whales shows that only males produce these vocalizations. The sounds are simple and consist of low-frequency moans and grunts and high-frequency pulses. Scientists suspect that males emit these sounds to attract females from great distances, and they worry that sounds from commercial ships, military sonar, seismic surveys, and ocean acoustic research may reduce the distance over which receptive females can hear the vocalizations of males.

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Of all the large whales, perhaps the least is known about sei (pronounced say) whales. In the southern part of their range sei whales coexist with Bryde’s whales, and until the early 1900s, they were considered the same species. The name “sei” comes from the Norwegian word “seje”, which means pollock, because sei whales appeared off the coast of Norway each year at the same time large schools of pollock arrived to feed on the abundant plankton. Sei whales are sleek and streamlined, and are one of the fastest swimming baleen whales, reaching speeds of 22 mph. They may reach a length of 65 ft. (20 m), but a length of 54 to 55 ft. (3.7 to 16.8 m) and a weight of 14 to 17 tons is more typical. Sei whales have a dark bluish-gray body with white on the ventral surface. The flukes and flippers are dark on both the dorsal and ventral surfaces. The snout is pointed, and there is a single prominent rostral ridge running from the blowholes to the snout. The dorsal fin is tall and curved, and the baleen is uniformly ashy black with fine, silky fringes. Sei whales normally feed near the surface, and they are primarily skimmers instead of gulpers like blue and fin whales. Small copepods are their preferred food, although they will also eat other zooplankton and small fish.

Minke Whale
Minke Whale

 

Minke whales are the smallest of the rorquals. Males average 26 ft. (8 m), and females average 27 ft.(8.2 m). Both males and females weigh approximately 10 tons. The story is that the minke (pronounced mink-ey) whale was named after a Norwegian whale spotter named Meincke, who mistakenly identified a small minke whale as a blue whale, the largest of all whales. Minke whales have a very narrow, pointed jaw, a single ridge that runs from the tip of the jaw to the blowhole, and a dorsal fin that is tall and curved. The flippers are slender and pointed at the tips, and the flukes are broad, pointed, and notched in the center. The body is dark gray on the back and white on the ventral surface. There is a distinctive white band on each flipper, and the extent and orientation of the band varies between individuals. The baleen is yellowish-white. Minke whales have an inconspicuous blow that is often hard to spot in the ocean, but they do occasionally breach, and you can see the white fin band on the fin of the breaching minke in the above photo.

My post next week will be about the most famous member of the rorqual family, the humpback whale. Please let me know if you have any questions or would like to add anything to these posts.

For those of you who are mystery lovers, please visit my home page and sign up for my monthly Mystery Newsletter.

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

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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!

In late November or early December, I plan to start a monthly newsletter focused more on mysteries and my fiction writing. My first several newsletters will chronicle some true-life Alaska crimes. If this sounds interesting, please subscribe to my e-mail list.

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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