whale behavior and family life

From: Dagmar Fertl (dagmar_fertl@hotmail.com)
Date: Mon Oct 30 2000 - 11:25:18 EST


Dear Dagmar,
I am a Year 4 student in Australia doing a project all about whales. I have
found most of my information already ( most thanks to whale-net) , but I
still have a few unanswered. I was wondering if you could help me
please.These are my questions:
1. Are whales diurnal or nocturnal?
2.How do they protect themselves?
3.How long is the gestation period?
4.How long does the young stay with it's parents and who looks after it?
5.How many young do they usually have at once?

Thankyou so much for your help I am very grateful.
Best wishes,
Christopher.
********************************
Hi Christopher, thanks for sending your questions in to WhaleNet.
1. Whales are on the move day and night. There are some dolphin and whale
species that feed more during the night than the day - feeding on the deep
scattering layer that moves up closer to the water's surface at night. Since
whales and dolphins need to breathe air at the water's surface, they need to
somehow be awake to breathe. Hope that answers your question without getting
too detailed.

2. It depends on the whale and dolphin as to how they protect themselves.
Probably the most effective weapon that a whale has is its tail. The tail is
very powerful, since that is the only way that the whale can push itself
through the water. Whales and dolphins sometimes group together to protect
themselves. Whales with teeth might also use their teeth to help defend
themselves. Dolphins often use their beaks, which are solid bone, to hit
with. Another way to defend yourself would be to get away from the
trouble...by swimming away.

3. Gestation period depends on the species you're talking about. Gestation
period for baleen whales ranges between 10-13 months; 7-17 months for
toothed whales. So, for example, a blue whale has a gestation period of
11-12 months, while a sperm whale has one that is 14.5-15.5 months long.

4. The calf (baby whale) stays with its mother only. Males do not help to
raise the calf. Again, length of time that a calf stays with its mother
depends on the species. For example, a bottlenose dolphin stays with its
mother for 3-5 years, even though it is done nursing by the time it is 1.5
years old. Why stay longer? Learning is the reason...learning about the
environment, including about the other dolphins in the area, how to catch
fish, how to avoid predators, etc. Toothed whales are more social than
baleen whales are, so there is a longer period of care by the mother for
toothed whales, than for baleen whales.

5. Typically, there is only one calf born. Confirmed multiple births are
rare for whales in the wild.

Good luck with the project!

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