I was researching one of my posts
when I run into a picture of an air borne whale; it looked like it was trying
to get out of the water. A caption described the picture as a whale breaching.
It was the word breaching that caught my interest. Breaching is the progressive
sense of the verb breach in this context. Up until then it had never occurred
to me that the word breach had a zoological connotation or meaning.
I had known breach to mean a
violation of law. This made me curious, and the curiosity lead me to do this
post to be shared with you, even as I myself learn more about the subject. Breaching
occurs when a whale lifts itself out of water into the air, turns in the air
and falls back into the water. Technically, according to cetacean researcher,
Hal Whitehead, a breach is any leap in which at least 40% of the animal’s body
clears the water. It is said that a single breach costs a whale 0.0075% of its
total daily energy intake. For humpback whale to do a 90% clearance of water,
it needs to leave the water at 8 meters per second or 29 kilometers per hour
(18 mph). Breaching is done in series. The longest sustained jumps recorded were
done by a humpback whale near the West Indies. It did 130 jumps in less than 90
minutes.
Cetacean is an adjective derived
from the noun form which is also cetacean. The noun form according to the
Longman Dictionary of Contemporary English is a mammal (an animal that feeds
its babies on milk) that lives in the sea. These mammals include whales,
porpoises and dolphins.
There are two ways to breaching.
One is vertical, and the other is horizontal. In the vertical breach the whale
rises vertically out of the deep into the air to clear the water. In the other
method, the whale swims up to the surface and parallel to it, jerks upwards out
of the water.
REASONS FOR
BREACHING
The real reasons for breaching as
a surface behavior among whales are not known for sure. Marine biologists have
not given much research time to whale breaching. Reasons assigned for breaching
are therefore speculative. It may have to do with communication, defense or
preying behavior .The following are some suggestions:
1 Because
whales have the inclination to breach in a group it said that breaching is used
as a soundless way of communicating within the group during social behavior. A
hypothesis is that breaching is an alternative way of communicating among
whales as against underwater sound transmissions.
2 A
breach is seen as an indicator of physical fitness in the whale if it could
afford energy for such an acrobatic display, hence implying dominance, courting
or warning of danger.
3 It
is suggested that when falling back into the water, from a breach, the sound
generated from the fall, could be used to stun or scare prey. The forceful
impact, if directly on a prey, may render the prey unconscious for enough time
for the whale to swallow it. Perhaps it also allows the whale to land directly
on the prey without being bitten.
4 As
whales breach, more often than not, in rough seas, it is said that it is
possible whales breach to take in air that is not close to the surface and full
of spray.
5 Another
possible reason for breaching in whales is to drop off dead skin and parasites.
It is not known if whales breach intentionally to drop off top layer of skin
and parasites, as snakes shed their skin or as monkeys delouse themselves.
6 Another
thinking is that, maybe because of the increasing number of vessels on the high
seas, the whales have developed frequent breaching as a sign of being
territorial. They breach to, as it were, warn the human driven vessels that
they are coming too close, and to give them time to prepare for the moving
vessel. This gives mutual safety to both parties.
7 A
theory is that breaching facilitates quick travel and preying on fish.
Aerodynamically, leaving the water for the air for a short time may help whales
to travel fast over long distances.
It is only a matter of time that we
shall know the real reasons why whales breach.
Reference:
http://www.wisegeek.com/why-do-whales-breach.htm
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