|
CETACEANS
|
|
ANATOMY
|
|
|
Those
are the chief words you have to know |
|
Cetaceans is divided
in two suborders, Misticeti (11 species) and Odontoceti (67 species).
|
|
It's own their name to indicate us the respective peculiarities, in fact
the Misticeto term draws origin from the Greek word Mystax (that it means "moustaches") to indicate the presence of the so-called fanoni
(corneous laminae with filtering function); Odontoceto
instead derives from the Greek word Odontos (that it means "tooth").
|
|
COMMON
CHARACTERS |
|
The cetaceans have developed to a body a lot
streamlined and hydrofoil, the front limbs have been transformed in
fins, while those posterior ones have gone completely lost, the tail
have been transformed in the propulsive organ developing an
exceptional muscolature, on its top those have been developed to two
tail lobes and in the greater part of the cetaceans (that need of a sure
speed) have appeared the not joined dorsal fin to the skeleton, with
stabilizer function. The movement from the high one towards the
bottom of the tail, typical of the swim of the cetaceans, has had to
the land origin of the same ones, their vertebral column did flex and still flex in vertical sense (in the fish horizontal with vertical tail).
Disappeared the hair replaced in its function of thermal insulator
from layers adiposeness. The skull has endured a deformation that has leaded
the nostrills on its top for one greater comfort in the respiration
during the swim. Cetaceans emits wide range of sounds having a function of
large sociality (in some species every individual seems to have a "name" marked
by one personal sonorous emission). They are totally unprovided of
olfaction. The sleep is in truth drowsiness with regular
respirators intervals, in the Tursiops has been
demonstrated the ability to make sleep half brain for time.
Equipped of great brains, in some cases greater than that human (Sperm whale 8 kg,
Killer whale 5.6 kg) but, and that is the important, second
in the animal reign only to the man in the relationship between body weight and
brain weight . |
|
THE MISTICETI |
|
   The Misticeti catch up
enormous dimensions (twenty or thirty meters and many tens of tons),
they have the airhole formed from two orifices and their jaws are
corneous sheet supplies in said variable number and dimension fanons.
Their sociality is bound from the fulfillment of long migrations in search of the food and in
reproductive scopes, in spite of that succeeds to communicate to enormous distances
(hundred of
kilometers emitting sounds to vlf) increasing the such way the
concept of shoal. They do not emit sounds for the ecolocation.
They have developed to peculiar
predatory technical due to the type
of food they eats mainly composed from animals of plancton
and small fish. |
The hunting techniques are many;
exist the so-called filtrators that swim slowly with the enormous opened wide
mouth, equipped of long fanons, literally skimming the plancton from
the water;  |
 there are the
swallower, that adopt a mainly predatory behavior, they in fact are equipped of
underthroat folds
that allows to swallow enormous water amounts in order to expel with force, also thanks to the powerful
tongue, through the courts fanons, forming therefore in mouth a bolus to
swallow. This last
Misticeti has developed technical of hunting many assets, also for the
type of prey of which they feed that it is not limited, like the
plancton, to let be transported from the currents but it is escaping
express. |
Some species operates an encirclement and forces the
prey in the most driven in shoals for
example with columns of
emitted air bubbles from many meters of depth (Megattera), or
goes to rouse  small crustaceans
moving the sounding-depth with
the snout (grey Whale), other completes wide movements with the
mouth in order to swallow the greater water amount (common Finner). |
|
THE ODONTOCETI |
|
The Odontoceti are medium much smaller of Misticeti
(also 1.4 m as an example the Focena) but in some cases they catch up a remarkable size
(sperm whale even if its positioning
between the Odontoceti is still object of arguments), has one airhole equipped of an only orifice. They manifest strong and
long-lasting social ties.
|
|
The predatory techniques of the Odontoceti
are several, that because of the enormous variety of possible prey
they eats. |
|
Some of them complete the deepest immersions, fighting with monstrous
prey like the giant squids or more simply with octopussy (sperm
whale), others with exit nearly
completely from the water for feeding of seals or assault in shoals the enormous
Misticeti (killer whale). |
|
But what mainly differentiates
the Odontoceti from the Misticeti is the possibility to use (also in
order to characterize the prey, but not only) the biosonar, a
magnificent instrument of ecolocating thanks to which, through
the emission of sonorous waves to most vhf (click) and the captation
of the return echo, succeeds to characterize objects and obstacles
also in the more absolute darkness. |
|
|
 |
 |
 living species |
| why here |
| Mediterranean |
| pictures |
 |
| introduction |
| evolution |
| cetology |
| feeding |
| classification |
| cetaceans in numbers |
| sea sounds |
 |
| your pictures |
|
