THE ORCA KILLER WHALE

The largest members of the dolphin family are often the killer whales. They are members of the Order Artiodactyla, Family Delphinidae, Genus Ornicus, Phylum Chordata, Class Mammalia, Kingdom Animalia, and Species Orca. Ornicus orca is their scientific or binomial name. Since they were seen hunting and preying on certain other huge species of whales, they were given this scientific name. The backs of killer whales are typically black, whereas their sides and chests are often white. However, they are distinguished by the white patches that are typically present above and behind their eyes. They usually occur in three types which are Resident, Transient and offshore killer whales. One unique fact about killer whales is that they are the apex predators hence no other organisms feed on them. This gives them an advantage as opposed to other whales and dolphins since their population is able to increase steadily unless where factors such as death affect the size of the population. These toothed whales have a diet that is diverse ranging from fish to marine mammals such as dolphins as well as seals. In addition, their distribution is also diverse and can be found in different in marine environments such as the tropical seas and the Antarctic and Artic marine environments (Giles, 2014).

Sensory systems /Specializations

Killer whales have a well-developed auditory system which enables them to recognize different sounds when under water. The presence of a well-developed auditory system in whales is enhanced by the highly specialized brain and nervous of the killer whales which is able to detect any sound made and process it at a faster rate than the brain and nervous system of human beings. Killer whales have several adaptations that enable them to detect sound in their surrounding such as the presence of fat lobes in their lower jaw. Fat lobes in the lower jaw are used to pass on any sound to the ears of the whale. On the other hand, unlike in many animals, the skull lacks the ear bone complex which is also known as ootic capsule. The ear bone complex is instead located in a hollow space outside the skull. In this hollow space or cavity, the ear bone complex is supported by ligaments therefore it is able to quickly identify the direction of a given sound. This helps the killer whales to identify their prey as well as communicate with other whales in their environment (Hargrove, 2015).

On the other hand, killer whales have well developed eyesight in addition to auditory system. Killer whales have several adaptations that enable them to have clear eyesight while under water which is a challenge to other land mammals. First, killer whales have an advanced convex lens than that of land mammals which replaces the inability of the cornea to focus light rays to the lens. The refractive index of water which is similar to the refractive index of the eye’s interior makes it difficult for the cornea to direct light rays to the lens. In addition, when the killer whales are in the air, they constrict their pupil o the eye to reduce the refraction at the interface of air and the cornea. Like most crustaceans, killer whales are not able to recognize color in blue wavelengths due to the absence of color pigments (Perrin et al, 2009).

To complement the presence of a well-developed auditory and visual system, killer whales have a well-developed sense of touch. This has been proved through observation of different behaviors among killer whales. Some of the regions in killer whales that are more sensitive are the regions around the ears and eyes as well as the blowhole region.

Methods of intraspecific communication

Killer whales mainly depend on sound to be able to find their way in the water and also to communicate with others. Where the water is dark or murky, use of sound becomes very effective since the killer whales cannot be able to see with their eyes. To be able to communicate, killer whales use a variety of techniques which include; making pulsed calls and echolocation clicks, producing whistles and low-frequency pops as well as the use of jaw claps (Annie et al, 2010).

Whistles are used by the killer whales for communication within a close range. Whistles are usually of a high pitch and help the killer whales to quickly locate other killer whales or their prey. The ability of whistle to show direction precisely, limits their ability to travel for long distances hence they are mostly used for private communication or behavior interaction. On the other hand, the use of pulsed calls is the most widespread form of vocalization which is used by the killer whales. Pulsed calls help the killer whales in identifying other similar groups of killer whales that are in close range as well as coordinate their behaviors. Pulsed calls made by killer whales may differ depending on where they are located. In addition, killer whales living in a similar area are likely to use similar pulsed calls which may be different with those of killer whales living in another distant region. Calves, young ones of killer whales learn on the calls to make in different circumstances to promote communication.

In addition, echolocation involves the sending of waves in the water to be able to identify any objects in the water. This is a form of communication where the killer whale uses its own sound to be able to identify objects in its environment. The range of an object is determined by the duration of time between the emission of the sound and echoes returning from the environment. Use of echolocation helps the killer whales to determine the speed and direction of the objects in water .This helps them to easily catch prey in the water (Giles, 2014).

Habitat and distribution of Killer whales

In the category of mammals, killer whales are the most widespread since they inhabit all oceans across the world. Their population is close to that of humans because of their distribution in different parts of the world. In spite of being wide spread in different oceans, they are common in cold waters which are upwelling. They are more productive in these areas unlike in the warm areas. Some of the areas with a high population of killer whales include; higher latitudes of Southern Ocean, Pacific North West and the northern coast of Norway in the Atlantic. In spite of the majority of killer whales being found in the cold regions of the ocean, some are found in the warm areas such as Bahamas, the Galapagos Islands, Florida and Australia. This shows that killer whales can also survive in warm areas with the tropical waters. On the other hand, the population of fish that inhabits the rivers is very small compared to the greater population that is found in oceans. An example of a river that has a population of killer whales is the Elbe. Killer whales tend to occur in the rivers as a way of catching their prey, usually fish. In general, killer whales inhabit the shallow coastal waters as well as the deep waters. The distribution of killer whales depends on the type of killer whales which range from Transient, Resident and offshore Killer whales (Hargrove, 2015).

On the other hand, the migration of killer whales depends on the movement of their prey such as fish. This shows that the movement of killer whales is seasonal. Killer whales migrate according to the movement of their prey such as herring, mackerel and salmon or in some cases due to the presence of obstacles such as ice formations. In the north Atlantic areas such as Scotland and Norway, killer whales have shown to have a similar migration pattern with the herring. In addition, in other areas such as in the north Pacific, the killer whales migrate in a similar pattern to that of the salmon. This therefore builds on the evidence that there is a correlation between the movement of killer whales and their prey. In contrast, the movement of killer whales in the Arctic regions has shown to be correlated to the formation of ice in the water. The killer whales migrate in order to escape the ice. All killer whales have shown to follow a specific route during their migration all year round (Rose, 2011).

Reproduction in killer whales

Female killer whales become sexually mature between the age of seven and sixteen years. On the other hand, males become sexually mature at the age of ten to eighteen years. The females usually come in to heat also known as estrus at different times of the year. These periods are separated by periods of no cycles. Killer whales are polygamous therefore they can mate with different partners at different times.

Feeding behavior of killer whales

Killer whales are among the mammals at the top most rank of predators that live in water. They mostly rely on marine mammals such as dolphins and fish as their sources of food. Some of the examples of fish which are consumed by killer whales include salmon, bony fish and sharks. In addition, killer whales also feed on animals that are not mammals such as sea birds and penguins marine Different types of killer whales have different specialization which differs from one region to another. For example, resident whales mainly feed on fish such as salmon while transient whales feed on marine mammals such as the baleen whales and seals (Annie et al, 2010).

Once they have captured their prey, the killer whales swallow it whole. In some circumstances, they tear the prey for easy swallowing. To obtain their prey, killer whales may hunt in groups or individually. At most times, hunting in groups is advantageous since a number of whales are able to hunt a school of fish or a large number of marine mammals at once which is enough for themselves and their off springs. This is an advantage them since they easily obtain prey. On the other hand, a group of killer whales may team up to attack large marine mammals such as the baleen whales which are large in size. In rare incidences, individual killer whales slide on beach to catch their prey such as seals (Rose, 2011).

Intraspecific and antipredator defense behavior

Killer whales being one of the apex predators have fewer natural predators than other mammals. Some of the natural predators of killer whales are diseases and parasites and human beings. These predators have little impact on the killer whales since they cause death among few killer whales. In spite of having fewer predators, killer whales have mechanisms which enable them to be able to hunt their prey. The size of the killer whales is one of the major defenses that enable them to hunt effectively. They use their powerful tails to scare away their prey as well as catch them. For the use of the tail to be effective, they rely on their strong eyesight and acute sense of hearing to be able to find their way in the water either towards their prey or away from any danger. Moreover, the presence of sharp teeth and the ability to charge at others scares away many animals from the killer whales (Annie et al, 2010).

On the other hand, killer whales work together a in group which enables them to survive and remain healthy for long periods of time. They hunt in groups using various cooperative techniques hence they are able to easily catch prey such as seals or a school of fish such as salmon. In addition, working as group helps killer whales to destroy ice bergs that may be a challenge to them. This is mainly by making strong waves which can bring them down. Moreover, strong waves made by a group of waves also help to catch prey since they wash away the prey such as seals from their hide outs and take them back to the ocean where they can easily be caught by the killer whales. To reduce the effects of human activities on their health, killer whales can be able to sustain more human made toxins in their bodies for longer period of time than most marine mammals. Some of these toxins include chemicals which are as a result of pollution. Sometimes, killer whales tend to stay away from regions where fishing and other human activities take place to avoid noise pollution. This is due to the fact that noise lowers their echolocation abilities hence they are not able to easily detect prey or danger (Perrin et al, 20009).

Social organization of killer whales

Killer whales are marine mammals that are very social in nature. They can either live in nuclear or extended families called pods, clans or communities. Pods refers to the groups of killer whales that swim together and are usually related such brothers, sisters and cousins. Clans on the other hand refer to pods which have similar calls. Communities refer to a group of killer whales that are in a common range but are not necessarily related. The orca mother is vital in binding the family together. The orca mother and her children (daughters and sons) make up the maternal group. In many occasions, the female Orca killer whale is found swimming with members of his family or even his grandchildren in some circumstances (Annie et al, 2010).

The female orca killer whale takes care of the young and on average has four to six off springs in her life time. She is however assisted by her daughters as preparation for taking care of their own in the future. Females have a gestation period of about seventeen hours and most births take place in spring. Females start reproducing at an average age of thirteen years. The males on the other hand are considered to be reproductively mature at about the age of twelve to thirteen years when the dorsal fin starts to straighten up. This process is known as sprouting. Mating between the males and females does not follow any particular system since mating takes place when the females are on heat. On the other hand, mating is not specific to individuals since killer whales are polygamous in nature (Rose, 2011).

Behavioral observations

Many observers in the North Pacific have noted the presence of strong bonds between the mothers and their calves. When the calves are born, the mothers are always close to them and direct how they move. On the other hand, sea world observers noted that killer whales discipline their calves as they grow through activities such as scratching of teeth or restraining them from movement. This acts as a way of ensuring that they have appropriate behavior (Hargrove, 2015).

Moreover, individual killer whales in the oceans have been seen to demonstrate unique behaviors such as breaching, spy hoping and lob-tailing. Breaching is the behavior where a killer whale removes a big portion of its body out of the water and then lands on the surface or its back. Breaching can occur at once or in a sequence. Sky hoping on the other hand refers to an incidence where the whale rises vertically from the water level and the head can easily be seen. Lob-tailing also involves movement where the dorsal and pectoral fins slap on the water’s surface and make loud sounds below and above the water (Rose, 2011).

Due to the diverse nature of killer whales, a lot of researchers are still trying their best to find something new about killer whales each day. Most studies on killer whales are being conducted in marine zoological parks. Through marine zoological parks, many people have learnt to appreciate killer whales as unique marine mammals with distinct adaptations such as echolocation. In addition, in many regions across the world such as Washington have whale watching expeditions at different times to enable people appreciate the importance of whales as well as learn more about them (Annie et al, 2010).

Conclusion

Killer whales are very unique marine mammals that are widely distributed across the oceans of the world. They have well developed sensory systems such as the auditory system as well as eyesight which promote navigation, communication and catching of prey. They have a diverse diet ranging from fish such as salmon to other marine animals such as sea birds. This has promoted an increase in the population of killer whales. As a result, killer whales are not at the danger of extinction like other mammals. Killer whales live in pods, clans and communities hence they are able to hunt and swim together thus increasing their survival chances and ensuring that they also protect their young calves. In conclusion, Killer whales are among the most unique marine mammals that the world is privileged to have.



















References

Annie, A., Basil, U., Daniela, S., Ingrid, N., Jochen, Z., Laura, K., Nathan, T., Phil, B., Shamus, D., Taira, P., Tammy, J., Tim, M., Tommy,H., Vanessa, M., Warren, J. (2010). First Record of Predation on False Killer Whales (Pseudorca crassidens) by Killer Whales (Orcinus orca).Journal of Aquatic Mammals, Vol.36 (2); 195-204.

Giles, D. (2014). Southern resident killer whales (Orcinus orca) : The evolution of adaptive management practices for vessel-based killer whale watching in the Salish Sea ; A novel non-invasive method to study southern resident killer whales (Orcinus orca) and vessel compliance with regulation ; and, The effect of vessels on group cohesion and behavior of southern resident killer whales (Orcinus orca. Davis, Calif: University of California, Davis.

Hargrove, J. & Eoan, H. (2015). Beneath the surface : killer whales, SeaWorld, and the truth beyond Blackfish. New York, NY: Palgrave Macmillan.

Perrin, W., rsig, B. & Thewissen, J. (2009). Encyclopedia of marine mammals. Amsterdam Boston, Mass: Elsevier/Academic Press.

Rose, N. A. 2011. Killer Controversy: Why Orcas Should No Longer Be Kept in Captivity. Humane Society International and The Humane Society of the United States, Washington, D.C. 16.