Introduction The Order Cetacea is one of the most distinctive and highly specialized groups of mammals. Over the course of evolutionary history, cetaceans have become adapted to surviving and prospering in a vast aquatic environment. One of the most important obstacles they have overcome is the ability to be obligate ocean dwellers while still breathing oxygen. Cetaceans are able to remain underwater for extended periods of time, returning only to the surface to exhale. Diving beneath the surface is an essential component of life for these species since almost all of their food sources are found under the surface of the ocean. One of the most-well known diving cetaceans is the sperm whale (Physeter macrocephalus). The world’s largest carnivore, this massive cetacean makes extremely deep dives for food, mainly squid and octopus, but also fish and sometimes giant squid (Burnie and Wilson 2005). Sperm whales can dive to depths of 400 to 1200 meters, and for durations of up to 138 minutes (Watwood et al. 2006). The majority of sperm whale dives have been reported to last from 33 to 53 minutes (2006). Sperm whales have to overcome several fundamental problems while diving at such great depths: the effects of pressure and the need to actively forage while holding their breath. Adaptations to pressure have to deal with the mechanical effects of pressure and the increased solubility of gas at depth (Costa 2007). Adaptations to breath-holding diving center around modifications in metabolism, blood flow, and an increased oxygen storage capacity (2007). Effects of Pressure As sperm whales dive, they must deal with the direct effect of pressure that is associated with the volume change of air-filled spaces in their bodies. Changes in air v... ... middle of paper ... ...W, Rotstein DS, Rowles TK, Simmons SE, Van Bonn W, Weathersby PK, Weise MJ, Williams TM, Tyack PL (2011) Deadly diving? Physiological and behavioral management of decompression stress in diving mammals. Proceedings of the Royal Society of Biological Sciences. 279:1041-1050 Kooyman GL (1973) Respiratory adaptations of marine mammals. American Zoologist. 13(2):457-468 Miller PJO, Johnson MP, Tyack PL, Terray EA (2004) Swimming gaits, passive drag and buoyancy of diving sperm whales Physeter macrocephalus. The Journal of Experimental Biology. 207:1953-1967 Watkins WA, Daher MA, Fristrup KM, Howald TJ (1993) Sperm whales tagged with transponders and tracked underwater by sonar. Marine Mammal Society. 9(1):55-67 Watwood SL, Miller PJO, Johnson M, Madsen PT, Tyack PL (2006) Foraging behavior of sperm whales (Physeter macrocephalus). Journal of Animal Ecology 75(3):814-825
For this experiment, it is important to be familiar with the diving reflex. The diving reflex is found in all mammals and is mainly focused with the preservation of oxygen. The diving reflex refers to an animal surviving underwater without oxygen. They survive longer underwater than on dry land. In order for animals to remain under water for a longer period of time, they use their stored oxygen, decrease oxygen consumption, use anaerobic metabolism, as well as aquatic respiration (Usenko 2017). As stated by Michael Panneton, the size of oxygen stores in animals will also limit aerobic dive capacity (Panneton 2013). The temperature of the water also plays a role. The colder the water is, the larger the diving reflex of oxygen.
Oxygen breathing lungs are a universal trait of class reptilia. As such, it would have been necessary for the Plesiosauroid - a marine reptile, to return to the ocean surface to inhale air. Oxygen expenditure in reptiles is proportional to strenuosity of locomotion (Frappell, Schultz & Christian, 2002). Therefore the Plesiosauroid must have held physiological traits that enabled the species to avoid oxygen deficit while hunting deep-sea dwelling prey. This essay will outline the hypothesised respiratory, circulatory, pulmonary and sensory attributes of the Plesiosauroid as they relate to diving. These hypotheses will be supported by investigating the physiological adaptations of the Plesiosaur’s biological analogues, and the prospect of similar adaptations in the former will be speculated upon.
J. G. M. Thewissen and his colleagues changed the way in which scientists thought about the early lifestyles of whales. The evolution of the ancient artiodactyls was discovered to be joined with the well-known group of cetaceans. The tertiary period was a time of terrestrial life forms. Every mammal walked the earth. It wasn’t uncommon to see a whale running through the grasslands or shark sleeping on the coast of a land mass. It was a time when mammals roamed freely and unconfined by the limits of the ocean. Now that scientists have this newly found knowledge, it is time the scientists further investigate “why?”
“… building a tank the size of Rhode Island wouldn’t be large enough for a six-ton male killer whale such as Tilikum, an animal capable of swimming 100 miles a day,” states an anonymous whale expert. Whales have been in captivity since 1861 when P.T. Barnum displayed the first live whale that was captured in Canada. However, Barnum had no idea how to care for the mammal and it died after only a week in captivity. (Animal Legal and Historical Center, 2014) Being up close with killer whales could give us some clues about how they interact with each other, including physical behavior, their dialect, and how their pods work together as a family unit. However, what we are finding is that whales who belong in the wild are suffering in captivity. Killer whales have no record of ever harming a human being in the wild. In captivity, there have been many incidents of killer whales harming or even killing their trainers. What would cause them to do this in captivity, but not in the wild? They have been known to resort to aggression toward themselves and each other, in what scientist believe to be a stress induced behavior. (Animal Legal and Historical Center, 2014) Evidence against having these wild animals in captivity is increasing and we need reevaluate the value of capturing and holding killer whales for our educational purposes, enjoyment, and profit.
Marine mammals are able to suffer from decompression sickness, which is a condition that occurs when sudden decompression causes nitrogen bubbles to form in the blood and tissues of the body. The lifestyles of marine mammals makes them susceptible to this condition, however, they have adapted to overcome this obstacle. Many marine mammals are capable of storing gas in their trachea during dives. The trachea is reinforced by cartilage, which supports its structure during dives where the lungs collapse under pressure. This prevents the gas from being forced into the bloodstream, also preventing nitrogen from entering the blood. Increased myoglobin concentrations, increased blood volume, and decreased lung size relative to body size are also adaptations seen in diving mammals (Hooker et al., 2011).
Killer whales communicate by a series of clicks and whistles called vocalization. Each pod, or family, has their own unique language. This gives whales the ability to identify their own pods. Orcas have a brain that is about five ti...
The killer whales living at the SeaWorld park also undergo large amount of stress while living in the pools. Everyday, the whales practice tricks with different trainers. If the whale doesn’t do a trick, they are starved for the day or until the trick is completed the way the trainers want. The lack of food for an eight ton animal is critical and can lead to serious problems. Many times the whales will take out their anger on whales around them but have also been known to go after a trainer when not being fed.
The reason baby Gore Ottsen survived is due to a evolutionary reflex called the mammalian diving reflex. This reflex is found in mammals such as dolphins and whales who cannot breathe underwater. These animals must come up to the surface to breathe and then carry their air with them as they swim. For example, sperm whales are able to dive deeper than 1000 meters and store up to 3000 liters of air before a dive. How can a mammal stay underwater for so long? Similar to baby Gore Ottsen, the mammalian diving reflex allowing them to stay submerged for extended periods of time.
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
The decline of the dinosaurs brought the evolution of a new marine order know as Cetacea. Present day species of whales and dolphins began to emerge 10 million years ago. Of these 86 species that exist today, whales make up the majority of both the Odonotocetes and Mysticetes. These creatures are amongst the largest in the world and display an equally unique way of communicating with one another. Both baleen and toothed whales communicate utilizing sounds yet neither possess an external ear. Sounds are detected through a fatty structure that rests in between the middle ear and the mandible while the sounds given off to communicate vary between species, or in an orca's case, between pods. Mysticetes do not contain any vocal cords but instead have vocal folds that they communicate with and generate some of the most resounding biological sounds known to man. These series of clicks and moans come together as a whale song and is used to communicate anything from possible threats to identification of another whale to mating calls. Odonotocetes communicate a little differently by emitting high-pitched sounds and echoes to navigate themselves and determine the location of objects. Echolocation is imparative and provides a three dimensional view of the world below where only 1% of sunlight travels to 100 meters in depth. Migratory whales communicate through these methods across vast distances like 4,500 kilometers and continue to produce the same sounds between each other. Even when the slight changes between clans occur seasonally, the rest of the members in other breeding grounds follow suit. In 1996, when two individual Humpback whales ventured from the Indian Ocean to the Pacific ocean with their own unique song it was onl...
Cold water is the key aspect in the phenomenon called the mammalian diving reflex. This reflex has been beneficially used for thousands of years by whales, dolphins, seals and other mammals that inhabit the frigid waters of the world. The diving reflex slows heart rate and causes peripheral vasoconstriction to keep blood and oxygen to the brain and other vital core organs. This reflex allows these mammals to conserve oxygen and stay submerged over longer periods of time, providing them more time for finding food, protection and travel.
Before commencement of the diving reflex, three critical changes have to occur to the body in order to stimulate the diving reflex. First to occur is change in the heart rate, this occurs immediately when the face has contact with cold water the human heart rate slows down ten to twenty-five percent. Seals for example undergo extreme changes in their heart rates, from going approximately 125 beats per minute to as low as 10 on a lengthened dive. (Arterial gas tensions, 1989). By slowing the heart rate it reduces the need for bloodstream oxygen, dispensing more to be utilized by other vital organs. Following the heart rate changes peripheral vasoconstriction sets in, which is the narrowing of blood vessels to reduce blood flow and is achieved by a muscular contraction in the blood vessel walls. This decreases the amount of blood that flows to peripheral organs in which do not need a high level of oxygen to function. This is the prevention of blood circulation to certain areas, first to close off are the Toes and fingers, then hands and feet, and ultimately arms and legs. The constriction allows for more blood for use by the heart, brain and organs. Lastly, the blood shift that occurs only during very deep dives. When this happens organ and circulatory walls allow plasma and water to pass freely throughout the thoracic cavity, so its pressure stays constant and prevents the organs from being crushed. In this stage, the lungs' alveoli fill up with blood plasma, which is reabsorbed as soon as the animal leaves the pressurized surrounding. This stage of the diving reflex has been observed in humans such as deep diving scuba divers, who can reach distances of approximately 90+ metres. Therefore, both a conscious and an unconscious pers...
Whales are some of the ocean’s most fascinating amphibious beings. They possess highly acquired communication skills and are believed to have an intelligence level equal to, and in some species, surpass that of the human brain. The biological, anthropological, and marine educational communities have studied the whale in a way that sheds light onto the studies of evolution as well. Yet, there are industries that subject these animals to captivity, hindering the natural development of these animals. Of all the communities contributing to the protection and study of the whale, there is one tipping the scale towards exploiting it for profit: The entertainment industry.
The Humpback Whale, Megaptera novaeangliae, is part of the marine mammals group. They are found in oceans all over the world, they live in open waters. Even though they are mammals, they do not live on land (Monterey Bay Aquarium). Humpback whales are known for their magical song that can travel great distances. These gentle giants are omnivores, their main diet is krill. They are mostly found near coastlines feeding on tiny shrimp-like krill, plankton and small fish. Humpbacks migrate annually from summer feeding grounds near the poles to warmer winter breeding water closer to the Equator. Humpback whales are powerful swimmers, and they use their massive tail fin, called a fluke to propel themselves through or even out of the water! Mothers and their young swim close together, often touching one another with their flippers with what appears to be gestures of affection. Even though it takes more than one year for a humpback whale to grow fully, mother whales leave them after one year (National Geographic).
...d insulates the body. Whales have a spinal column, a vestigial pelvic bone, and a four-chambered heart. The neck vertebrae are typically fused, trading flexibility for stability during swimming. ("Whale." Wikipedia. Wikimedia Foundation, 13 May 2014. Web. 15 May 2014).