Orcas: Killer Beauties

Senses & Communication

 

 

Hearing Sense and Auditory Range.

The Orcas has a very well developed sense of hearing. The auditive crust of the brain is highly developed. The auditory range of the orcas is located between frequencies from 0,5 to 100 kHz in comparation with the auditory rank of the humans which is from only 0,02 to 17 kHz. Maximum sensitivity of the Orcas are 15 kHz.

Sound Reception.

Most of the sound reception take place probably at the inferior jaw. The Orcas can also receive trough the soft tissue and bones that surrounds ear. The inferior jaw bone, which is full of blubber, apparently conduce the sound waves, by jaw bones until the medium ear.

The inferior jaw of the toothed whales is wide and hollow in the base, where it is united to the skull. Within this bone, very thin, there is a blubber deposit that extends until the back side of the auditory area, where is the assembly of auditory bones. The sounds are conducted trough this bone to the medium ear and then to the auditory centers of the brain, by the auditive nerve.

The Orcas has a small auditory opening at a few inches behind the eyes. Each opening conducts to a reduced channel and a eardrum. Some scientists think that the Orcas can receive sounds trough these openings, others think that the same openings are not functional. A type of foam surrounds the ear bones at all sides. This foam contains air. This air stops the sound waves that travel by the water and live tissues. Several scientists think that this foam acoustic isolates the ears, allowing the Orca to know from what direction the sound comes.

 

 

Eye's Sight.

The Orcas has a highly developed sense of sight, in both environments: Inside and outside the water. Their eyes, almost of the same size that a bull's eyes, are at each side of the head, just behind and above of the mouth. Glands located at the ends of eyes orbit, secret an oily mucus, like a jelly, that lubricates, clean the impurities and probably aid to maintain the eyes free while the Orca swims. This secretion can also protect the eye of infective organisms.

Tact.

Some characteristics of the Orcas, indicates that sense of tact is well developed. The skin of the Orcas is sensible to the tact.

Sense of Smell

The olfactory bulbs on the brain and the olfactory nerves are absent in all the indented whales, like also in the Orcas, indicating that they do not have sense of the sense of smell.

The Importance of the Sound in the Sea.

The Orcas probably trusts in the sound production and reception to navigate, to communicate, and to hunt in dark and gloomy waters, more than their eye sight. Under these conditions, the sight is of little use or useless at all.

Sound Production.

The Odontocetes can produce sounds for two fundamental functions: communication and navigation. An Orca can communicate and sail simultaneously. The Orcas produces clicks and sounds that seem moaned, grunts and whines. Also they produce whistles. They produce these sounds in any depth.

These sounds vary in volume, length of wave, frequency and type; all and each one of the sounds that an Orca produces are knows as calls. Calls which sounds equal of time to time are structured calls. All the structured calls in an Orca repertoire constitute a call system knows as dialect. Although scientists have noted that there is some type of arrangement or structure in the calls are, a dialect is not the same thing like a language.

The individuals of any particular pod share the same repertoire of calls. Pods that associate with one another share certain calls, but the vocal repertoires of each pod remain distinct enough so scientists can identify pods by the sounds they make. The Orcas that are separated by great distances, have different calls. 

The larynx of toothed whales does not have vocal cords as same with the Orcas. The sounds are probably produced when the animal forces the air between the nasal sacs and the region of the blowhole. During some vocalizations, the Orcas releases some air from the blowhole. Frequencies of the sounds produced by an Orca oscillates between 0,1 kHz to 40 kHz. Most of the sounds produced as a part of social behavior are in frequencies of 16 kHz. The higher frequency clicks probably work in the Echolocation.

The Orca Sonar: An incredible sound machine.

A marauding shark cruises the depths. A school of salmons far ahead. On the surface a boat's hull slides trough the waves. Long before it can see such objects, the Orca detects them. It has no sense of smell. Instead of it the Orca trust in a skull adapted to send and receive sound signals, and on a large and complex brain to interpret them.

A swimming Orca emits many sounds and clicks. When those clicks strike an object, they return and are transmitted to the animals brain, which interprets them and it lets the animal to know what is, how far is, how speedy is and its size. This process is known as Echolocation.

The Echolocation

The term Echolocation refers to ability that Odontocetes (and some other marine mammals and most bats) possess that enables them to locate and discriminate objects by listening for echoes. Odontocetes echolocate by producing clicking sounds and then receiving and interpreting the resulting echo. The Odontocetes echo-locates producing sounds similar to a click, then they receive and interpret the resulting echoes.

The Orcas produces directional clicks. Each click lasts less than 1 to 5 ms. These clicks include an ample range of frequencies. A peak of 25- kHz is common. The individuals can probably vary the frequency of the clicks to suit the circumstances.

The clicks travel through the melon, (the round region in the forehead of the Orcas) that is formed by lipids (fats). The melon acts like an acoustic lens to focus these sound waves, which is project forward into water and returns to the Orca as an echo.

The sound waves travel through the water at an approximated speed of 1 mile per second (1,6 km/sec), which is four and a half times as fast as sound traveling through air. The sound waves produced by a killer whale bounce off objects in the water and return to the orca as an echo. The sounds of high frequency do not travel far in the water. Because of their longer wavelength and greater energy, the long frequency sounds travel e farther.

The areas of greater auditory reception are the fat cavities of the bones of the inferior jaw. The sounds are received and are leaded through the inferior jaw to the middle ear, to the inner ear, and then to the auditory centers in the brain via the auditory nerve. Then the brain receives the sound waves in form of nervous impulses, which transmits the sound messages and allows the Orcas to interpret the meaning of the sound. 

Thanks to this complex of Echolocation, the Odontocetes can determine the size, forms, speed, distance, direction, and even the internal structure of the objects in the water. As many of the Echolocation details are not yet understood completely, it's known that some Orcas can identify the objects that are behind a wall. This means that probably they use some ultrasonic sounds to "see" hidden objects. Researchers have noted that some dolphins can identify the internally affected areas of the body on some animals as in the human been.

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