General whale biology

From: Pieter Arend Folkens (animalbytes@earthlink.net)
Date: Mon Nov 18 2002 - 02:32:06 EST

  • Next message: Pieter Arend Folkens: "Parody"

    >I am taking a Marine Biology class where one of my projects is to
    >interview a scientist. Well I choose a subject - whales - and need
    >a scientist to answer some questions for me. Would you mind taking
    >a few minutes out of your busy schedule to answer them? Please there
    >is absolutely no obligation here, if you don't want to by all means
    >just tell me that you would really rather not.

    The program moderator has asked that the questions and answers be
    embedded in an email. Here goes . . .

    Questions

    1. How do whales sleep?
    A Whales float. Because of this they do not experience the same
    physical rigors of animals that must keep balanced most of the day,
    and so apparently do not have the same degree of need for sleep.
    Whales also have the need to breathe. It appears that a whale will go
    into a rest state in which one side of the brain goes into a deep
    sleep, and the other side stays awake enough to remember to rise to
    the surface and breathe. After 45 minutes or so the brain halves
    switch resting states with the other sleeping.

    2. Why do whales migrate such long distances?
    A Not all do. The essential need for seasonal migrations of
    some species revolves around the physical differences between
    breeding areas and feeding areas. The key character of the breeding
    areas is warmth. A calf is more likely to survive if born into a
    warm-water environment. Looked at a different way, the cow does
    better if the calf is born small. A calf born into a cold environment
    would need an insulating layer of blubber at birth in order to
    survive. A calf carrying an insulating layer would be larger down the
    birth canal, and hence be tougher on the mother. Why not stay in the
    Tropics all year? Not enough food. Warm water does not hold some
    necessary nutrients in sufficient quantities to facilitate
    large-scale food production. This is why the water in the tropics is
    so clear. The opposite is true in the colder, 'anti-tropical' waters
    where upwelling and sufficient nutrients provide huge blooms of
    plankton that form the basis of the extended food chain. We think
    that during periods of colder overall global temperatures (during the
    ice age for example), calves were born in the Tropics, but the cool
    waters producing large food supplies were much closer. As things
    warmed up gradually, the migrating species became accustomed to
    traveling a bit farther for food. As distance became greater, the
    surviving species developed particular physiological and behavior
    characters that facilitated migrations.

    3. Do whales have any predators? If so, what are they and how do
    whales evade them?
    A The killer whale (which is actually a dolphin) is the top
    ocean predator. Their quarry includes most whale species. Humans are
    considered to be a major predator of whale. Large sharks may also
    prey on some cetaceans.

    4. What are the eating habits of carnivorous whales?
    A There are no herbivorous whales; therefore all whales are
    carnivorous (but not Carnivores). In a manner of speaking, it is the
    differing eating habits that differentiate the species, or at least
    the genera and families. All odontocetes are single prey item
    feeders, though the diversity of prey items is wide ranging from
    soft-bodied cephalopods (squid) to various sizes of vertebrate fish
    and to other whale (in the case of killer whales). Feeding behaviors
    are nearly as diverse as the number whale species. The discussion of
    each species' habits is beyond the scope of this program. I refer you
    to the book, National Audubon Society Guide to Marine Mammals of the
    World, and other books listed on the WhaleNet bibliography for more
    detailed information.

    5. What are the eating habits of baleen whales?
    A See item 4. Baleen whales utilize a variety of feeding
    techniques including skimming on non-aggregating copepods and similar
    prey; skimming on aggregating amphipods (krill); lunging on
    aggregating prey including krill and fish; and benthic feeding
    (sucking up bottom-dwelling organisms).

    6. How many different categories of whales are there? What are they?
    A By categories do you mean taxa? At one level of taxa there
    are three Suborders of whales: Archaeocetes, Mysticetes, and
    Odontocetes. Within each of those Suborders is a category called
    Families. (For example Balaenidae, Balaenopteridae, Neobalaenidae,
    and Eschrichtidae in the Suborder Mysticeti.) Within each of those
    families is another category called genera (or genus, singular). (For
    example Balaenoptera and Megaptera in the Family Balaenopteridae.)
    Each genus contains one or more species. (For example M. novaeangliae
    in the genus Megaptera.) Again I refer you to the publication
    National Audubon Society Guide to Marine Mammals of the World for a
    complete listing and explanation of the different categories of
    whales.

    7. How long do the whales tend to their young?
    A Depends on the species. Most mysticetes spend only a few
    months (6 to 12 months) rearing their young. For some odontocetes,
    such as killer whales for example, the period is several years.

    8. What is the average life cycle of a whale?
    A With around 80 species of whales there is great diversity in
    life histories. There is no reasonable "average."

    9. What are some of the common diseases for whales?
    A Parasites are common. These things can infect many of the
    tissues of whales, and are commonly found in the lungs, heart, and
    stomachs. Naturally occurring toxins like those coming from red tide
    are dangerous to whales. There are a number of viruses as well. You
    may find detailed information on this subject at the web site of The
    Marine Mammal Center in Sausalito. California. I believe their URL is
    www.TMMC.org.

    10. What are the various migration patterns of whales?
    A For those that migrate, the basic pattern is towards the
    tropics for breeding in winter and anti-tropical for feeding during
    summer months. In the north one example is the humpback whale. One
    population of humpbacks in the north breed in the Hawaiian Islands in
    winter and feeds in Southeast Alaska in the summer. In the south,
    some right whales migrate between coastal Patagonia in winter and
    Antarctica in summer. In each oceanic basin the actual routes vary by
    species and population.

    11. How long does it take an average whale to conceive?
    A Just minutes for conception when the time is right. If by
    your question you mean carrying a calf from conception to birth
    (gestation), this period varies, but is generally 10 months to a
    year, with some likely longer.

    12. How long does it take a whale to reach sexual maturity?
    A Depends on the whale. It varies widely. For some it is 3 or 4
    years. For many species the question is not sexual maturity, but year
    of first breeding. A species may become physiologically able to
    reproduce at an age of 5 or 6, but not participate in breeding until
    the age of 10 or 11.

    13. How many whales die each year from pollution?
    A No definitive records or quantification of such things.

    14. What is the average intelligence level of a whale, when compared
    to dolphins?
    A Technically, dolphins are whales. Both are in the Order of
    Cetacea. In general, mysticetes have smaller brains (proportionate to
    body size) and less encephalization than do odontocetes (which
    includes dolphins). A difference in intelligence is also demonstrated
    in social behaviors. Mysticetes tend not to maintain long-term family
    bonds or spend years rearing young, compared to many odontocetes
    which live in extended families (called pods or herds) and spend
    several years rearing young.

    15. Does the weather affect the way the whales interact with their
    environments?
    A Yes. That is a complex subject, but an obvious example is
    winter storms. Storms contribute to the creation of seasonal ice near
    the poles. Storms also push the ice around obscuring feeding habitats
    and forcing whales to migrate south. Another obvious weather event is
    El Niņo. This warm water event causes dramatic weather changes where
    ever it occurs. The changes are typically a reduction in productivity
    of the environment. This 'failure' causes whales to relocate for the
    time being in search of food. It can also cause premature mortality
    in adults and reduced natality (survivability of newborns).

    16. How keen is a whale's eyesight?
    A Depends on the whale. Whale eyes have U-shaped irises in
    bright light. These irises open up to large circles in darkness. This
    provides good vision in a wider range of brightness than in many
    other species. Toothed whales tend to have smaller eyes, but these
    critters rely more on 'seeing with sound." They use echolocation for
    a sort of 'sonic vision' that is very keen.

    17. In what way would whales be a hazard to humans?
    A They could jump on your boat. I know of 4 instances in which
    this has happened. Whales could also come up under a boat and stave
    it in. A pilot whale has been recorded trying to take a person down
    to depths (supposedly to drown them). Killer whales have killed a
    couple of trainers and evidence from the field suggests some killer
    whales have jumped at people and tried to knock them into the water,
    ostensibly to feed on them. In Japan the waters are so polluted that
    eating the meat of whales from polluted waters can cause mercury
    poisioning.

    18. What is the average life expectancy of a whale?
    A Varies depending on the whale. 25 years is common for some;
    45-50 in others. Again, refer to the Field Guide mentioned above.

    19. What is the economical value of a whale? (i.e. Why are they harvested?)
    A In some places they are harvested for subsistence, as in
    aboriginal subsistence whaling. In other places they are killed for
    high-end delicacy consumption, as in Japan. In the 1950s a special
    oil from sperm whales was used as a high temperature lubricant in the
    nuclear power and weapons industries. Many Japanese believe that
    whales and dolphins eat too much fish, hurting their fisheries. This
    is an abjectly stupid and shameful argument as a justification for
    whaling. Any one who says such things should be soundly ridiculed and
    thought of as a fool.

    20. Why can't they live in fresh water?
    A Some dolphins do. Most whales have skin perfectly comfortable
    in the salty sea. When placed into a fresh water environment the
    whale will survive, at least for a while, but the skin becomes
    diseased because it is not accustomed to the pH balance and the lack
    of salts in the fresh water. This degradation of the skin puts the
    whale into a state of poor health which can deteriorate over time and
    short lifespan.

    21. What are some of our protection techniques for whales?
    A Don't hunt them. Keep their environment clean by not dumping
    human waste in their feeding areas. Establish sacntuaries in thier
    key breeding areas.

    22. Since we know that the Navy is doing sonar testing that is
    destroying the inner ears of the whales, why can't we help the whales
    before they beach themselves or drown to death?
    A First of all, the low frequency sonar involved in the present
    issue with Navy particularly affects beaked whales which have finely
    developed hearing. Mysticetes appear to not be as impacted by this
    testing. After the high-energy sound blast used in the testing, the
    catastrophic damage to the whales' ears is done. There is nothing one
    can do to save these individuals before or during stranding. The best
    way to help these whales is not do the testing.

    OPTIONAL INFORMATION

    What is you occupation and degree of education?
    A I am a professional science communicator with a reputation in
    the field of marine mammalogy. (I also have published a major text
    book on human osteology.) I was an adjunct professor in the Division
    of Natural History at the University of California, Santa Cruz for
    many years. I am a co-founding director of the Alaska Whale
    Foundation, and participate in a variety of research projects
    involving humpback whales, killer whales, and climate change.

    Cheers,

    Pieter Folkens
    Alaska Whale Foundation

    -- 
    

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