Week 3: The Humpback Whale
"Bigwinged New Englander"
The scientific name for humpback whales is Megaptera novaeanglieae, which means ‘big-winged New Englander’.The scientific name refers to the large flippers or pectoral fins characteristic of humpback whales, and the fact that the first humpback to be described was from New England.
Adult Humpbacks are About the Length of a School Bus
Humpback whales are considered a medium-sized baleen whale, with adults averaging 40-45 feet in length (about the size of a school bus) and weighing between 25 and 35 tons (approximately the same weight as 4-5 adult male elephants).The largest recorded humpback was 62-feet long (19m). As with all baleen whales, female humpbacks are larger than the males.Typically, an adult female is about a meter (3-feet) longer than most adult males.
Humpback whales are well known for their long pectoral fins or flippers that measure about 1/3 of their body length or upwards of 14-feet long! Humpbacks also have a bunch of distinct bumps or protrusions on their head called tubercles that make humpbacks easily identifiable. Each one of these tubercles has a single hair, and it is speculated that the hairs might serve a sensory function for a whales, perhaps allowing them to sense water currents, changes in water temperature, or to detect prey. Humpback whales, like blue whales and other rorqual whales, have a number of expandable pleats on the underside of the throat called ventral pleats.These pleats allow whales to expand their mouth to an enormous size when feeding so they can consume massive amounts of small prey at one time, or allow whales to appear larger when competing for access to a female on the breeding grounds.
Every Tail is Different
Individual humpback whales are easily identified by the markings on the underside of the tail or fluke (the word fluke refers to a cetacean’s tail).The underside of each humpback’s whale tail is as different as a human fingerprint.The color patterns range from all white to all black to somewhere in between. Many show scars from attacks by killer whales or entanglement encounters. Identifying individual whales is crucial to studies of free-ranging mammals like the humpback whale. From this data, we can learn vital information about populations and individuals, ranging from age, lifespan, reproductive histories, migration patterns, and population estimates to association patterns between individuals. In other words, questions regarding migration routes, how long whales live, who they hang out with and for how long, how many babies they have in one lifetime can all be answered by identifying individual whales based on their flukes.
Humpback Whales are Found Worldwide
Humpback whales are found throughout the world's oceans. Humpbacks in Hawaii and Alaska are part of the North Pacific population. North Pacific humpbacks feed in the summer from Northern California to British Columbia through Alaska into the Aleutian Islands and Kamchatka Peninsula and migrate to Hawaii, Mexico, Japan, Costa Rica, and the Philippines in the winter for mating and calving purposes. In the North Atlantic Ocean, humpback whales feed from the Gulf of Maine through Newfoundland, Labrador, Greenland, Iceland and Norway and migrate primarily to theWest Indies, where they mate and calve. In the Southern Hemisphere, humpbacks feed in waters around Antarctica and then migrate north to warmer waters around the South Pacific Islands, Africa, South America, and Australia for mating and calving. Although some humpback whales in South America and equatorial West Africa have been found to cross the equator when migrating, most populations of humpbacks rarely mix between Northern and Southern hemispheres.
Humpback Whales Migrate Each Year
Many baleen whales and some toothed whales (e.g., male sperm whales) travel thousands of miles between higher latitude feeding areas and lower latitude areas for breeding and calving purposes. For these nomadic whales, their home is as vast as the ocean itself, and the only boundaries that exist, are the places where land meets the sea. Our understanding of the distribution and migration of whales comes from whaling era records, individual identification of whales photographed in different locations, and recent advances in radio and satellite telemetry where tags are placed on whales and locations of whales downloaded via satellite. Humpback whales make one of the longest migrations of any mammal, migrating as far as 5,000 miles one-way (the same distance as flying round-trip between Maui and San Francisco) between productive high-latitude summer feeding areas and lower latitude breeding grounds. One humpback was photographed in Alaska and 39-days later photographed in Hawaii. As a result, we know that some humpback whales can make the one-way migration in just over a month (and maybe shorter).
Humpback Whales Fasat Each Year
Similar to some (but not all) other species of baleen whales, humpback whales undergo prolonged periods of fasting each year. For the most part, humpback whales have separated feeding from breeding and calving activities. Humpback whales feed in higher latitudes (40-60 degrees) each spring, summer and fall, and undergo prolonged periods of fasting during the winter. During the summer, the long days of sunlight combine with dissolved nutrients to produce dense swarms of plankton, creating seasonally rich and productive waters that the whales rely on for food.A humpback's diet consists of shrimp-like crustaceans called krill (euphausiids) and various types of small schooling fish, including herring, capelin, sand lance and mackerel. Observations of humpback whales feeding in winter breeding and calving grounds like Hawaii are rare.This is because lower latitude breeding areas are generally nutrient poor and do not have the quality or quantity of prey that humpbacks depend upon. As a result, humpback whales eat huge quantities of food each day during the warmer months when food is more abundant. Seasonal gorging allows them to store energy in the form of blubber so they can survive long periods of fasting in the winter.
The Lifecycle of Humpback Whales
Year One: Non-pregnant and non-lactating female humpback whales travel to breeding and calving grounds like Hawaii for the purposes of mating. Once pregnant, the female returns to higher latitudes where feeding opportunities are more abundant, feeding intensively until it is time to return to warmer waters around 11-12 months later to give birth. Because she gives birth and lactates while fasting, she feeds on as much food as possible (the bigger the better) during pregnancy to help ensure the viability and survival of her unborn calf.
Year Two: Although no one has ever documented a female humpback whale giving birth, the presence of tiny calves with dorsal fins still folded over and the remains of placenta indicate that at least some females are giving birth in Hawaii. Some females may also give birth along the migration. During the winter months, the mom nurses the calf and protects it from predators until it is strong enough to make the migration back to summer feeding areas. Although the calf is still nursing during these summer months, the calf will learn when, where and how to feed from its mother.
Year 3: Calves typically nurse for the first 6-12 months of life, usually separating by the end of the first year.These year-old calves are called yearlings, and by the end of the first year they have usually nearly doubled in length, typically approaching 28-30-feet, and increased their weight by about 8 times. After weaning, females often mate again, repeating the entire cycle again. Some female humpbacks do give birth in successive years, but because of the heavy drain on the physical condition of females during reproduction (e.g., lactating while fasting and migrating), most females give birth in a 2-3 year reproductive cycle.
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