>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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