Whales, misc questions on biology and conservation

From: Dagmar Fertl (dfertl@geo-marine.com)
Date: Thu Oct 21 2004 - 17:45:32 EDT

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    Question:

    Dagmar,

    Thank you as always for answering my science students' questions.

    From Quincy and Emily : How many babies can a whale have in a litter? How
    fast can the fastest whale swim?

    From Sam and Hannah: How big is the biggest bottlenose dolphin? What does
    the gas from boats do to whales?

    From Allie and Jabari: What kind of work do you do with the Navy? How many
    different kinds of dolphins are there? What is your favorite kind of
    dolphin and why?

    From Alexander and Sarah: How do people pollute the water that whales swim
    in? How come whales just swim into nets without knowing they are there?

    From Mikayla and Jeffrey: What is your least favorite whale and why? Has a
    whale ever bitten a human?

    Sue Shirley
    Dedham Country Day School
    Dedham, MA
    ***********************
    Answer:

    Dear Quince and Emily -

    Whales do not have litters, but only have one (and very rarely, two) babies
    at a time. If a whale has two babies, only one survives.

    It's a tricky question about how fast whales swim, and it's something I've
    talked about in previous WhaleNet archives. Most swimming speeds were
    traditionally done with the animal moving alongside a boat, but we know that
    whales can draft alongside a boat much like a small car driving down the
    highway alongside an 18-wheeler kind of gets 'sucked along' and without any
    additional effort, moves much faster. In short, I don't know the answer off
    the top of my head, b/c it really depends on what type of whale you want to
    know about. If you write back, and tell me which one, I'll do more work to
    look up that answer for you.

    Dear Sam and Hannah -

    The biggest bottlenose dolphins live in the very cold waters off the United
    Kingdom; they can reach 3.8 meters in length (12 ft, 6 inches) and weigh
    around 500 kg (1,100 pounds). Bottlenose dolphins living in warmer climates
    are typically smaller and weigh less.

    As for the question about gas, I'm not sure exactly what you're asking. Gas
    fuels boats, and of course, that puts out pollution into the air, which is
    not good for whales (and for that matter, people either). If you are kind of
    asking this question since at my last job I looked at the impacts of the oil
    and gas industry on whales and dolphins, you really are asking another
    question.....

    Dear Allie and Jabari -

    I actually work directly for an environmental consulting firm that does
    contract work for the Navy, as well as other clients who pay us. For the
    past three years, Geo-Marine, Inc (GMI) has been preparing marine resource
    assessments (MRAs) for the U.S. Navy’s operating areas (OPAREAs) in the
    Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. GMI is now beginning to
    provide the Navy with the most up-to-date and relevant information on marine
    resources found within their Pacific OPAREAs. The goal of a MRA is the
    description and documentation of the marine resources in an OPAREA and its
    vicinity, including both protected and commercial marine species. The
    assembled data and information in the MRA can help the Navy evaluate their
    future actions, allowing for informed decisions regarding the scheduling and
    location of training exercises or operations to mitigate potential impacts
    to protected and commercial marine resources. Unfortunately for me, none of
    this is field work, but it is interesting anyway, because I learn about
    marine mammals living in different areas.

    Hmmm. My favorite kind of dolphin. That's a tough one. It probably sounds
    lame, but I don't really have a 'favorite'. The bottlenose dolphin will
    always hold a special place in my heart since I studied them for my graduate
    degree, and they are very interesting to study. They use all sorts of
    behaviors to get food, and have all sorts of interesting interactions with
    other dolphins, seabirds, whales, and even sea turtles...that makes them
    pretty interesting to read about.

    Dear Alexander and Sarah -

    Pollution comes in many forms...the kind you can see, as well as the kind
    you can't. There is everything from chemicals you can't see and trash you
    can see in the water, as well as lots of manmade sounds in the water, which
    can disturb and even hurt whales and dolphins (such as explosions, sonar,
    boat noise, etc.)

    Some whales are known to echolocate, some are known to not. Toothed whales
    in general are thought be able to echolocate, while baleen whales do not.
    Echolocation is using sound waves to bounce off objects and then the animal
    listens for the return echo. This means that a dolphin has to be constantly
    talking all the time and listening, which can be tiring (and probably
    annoying) and it could be an easy way for a predator (like a killer whale)
    to hear the dolphin(s). Some nets are really hard to see, like monofilament
    (plastic) nets, because they are pretty much invisible underwater. If a
    dolphin isn't using its sonar or is busy and not paying attention, they
    could accidentally get caught in a net. Another possible reason for getting
    tangled in nets is that the animals know that the net is there, are feeding
    on fish or squid caught in the net, and then accidentally get caught in the
    net and panic (kind of like when you accidentally walk into a spider web and
    freak out).

    Dear Mikayla and Jeffrey -

    Wow, my least favorite whale? Hmmm. I think my least favorite whale is a
    dead whale. Very stinky! :-)

    Yes, whales bite humans all the time. Of course, the only whale that can
    'bite' is one that has teeth, right? Bottlenose dolphins (which are small
    toothed whales) have been known to bite (or more accurately 'rake' their
    teeth across people).

    Thanks for the cool questions!
    Dagmar Fertl



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