Human’s heart rate automatically slows as soon as a person’s face is completely submerged (Heller et al., 1998). At the end of the dive, heart rate returns at an above-normal rate to flush out the lactate from the muscles back into circulation (Withers, 1992). The period of increased oxygen consumption after a dive is proportional to the amount of oxygen “debt” an animal is after a dive (Withers, 2009). When a marine mammal dives, the majority of the blood flow and available oxygen goes to the animal’s heart and brain (Heller et al., 1998). Scientists have observed that although the heart structure of cetaceans and pinnipeds are very similar to other mammals, one major difference are the enlarged stores of glycogen present in their hearts not found in terrestrial mammals (Berta et al., 2006).
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).
Through fossil records scientist have evidence that show how anatomical and physiological alterations occurred to species that caused them to turn from aquatic animals to terrestrial animals. The following are gradual changes that took place in species respiratory system, and will allow some underwater invertebrates to transform to land-dwelling vertebrates through evolution. It is said that fish were amongst the first species to live on Earth. The first invertebrates on Earth were jawless fish that used gills to breathe underwater, which are capillary-filled flaps near the mouth. When water flows over the gills, the blood in the capillaries exchanges carbon dioxide for oxygen; a process known as gas exchange.
Dolphins have a slower heart beat when diving so they can’t dive as deep and as fast as other mammals. When human divers dive to deep places they have to come up slowly or their gasses in their body will form bubbles which are very painful and are called the bends but dolphins or any marine mammal don't get the bends. Dolphins have a body temperature that is very stable which is usually 96 degrees. Dolphins can be in very cold water and not die because of their skin and tissue that covers their body (Monterey Bay Aquarium).
Although reptiles primarily use the environment for thermal exchange, there are physiological mechanisms that these animals do have to aid in thermal regulation. For example, changing skin color from a lighter shade of green to a dark shade of brown to increase absorption of heat. Reptiles can also shut down body processes and enter a state of dormancy in order to survive low temperatures or stressful environmental pressures. Reptilian dormancy is known as brumation and is similar to hibernation. Reptiles usually enter brumation in late fall when temperatures and day length decrease.
Great hammerheads are the largest species of hammerhead shark. The great hammerhead can be distinguished from other hammerheads by the shape of its “hammer” (called the “cephalofoil”), which is wide an almost straight front margin, and by its tall, sickle-shaped first dorsal fin. (Wikipedia, 2014) The function of the hammer is widely unknown but many theories have been put forward as to its purpose. The most popular are that it helps the great hammerhead to scan larger areas of the ocean floor for food, and it maximises the area of sensory organs known as the ampullae of Lorenzini that can detect chemical, physical and thermal changes in the water, as well as electric fields. (MarineBio.org, 2014) The body of the great hammerhead is the biggest of the nine species of hammerhead sharks and is coloured grey-brown to olive green on top and off-white below.
In fact, they are highly specialized for their particular mode of life and have undergone considerable changes during their long evolutionary history¡K¡¨ (14 Ross). ¡§Among living vertebrates, crocodilians are most closely related to birds rather than to lizards¡¨ (14). Even though these two groups are now adapted to different modes of life, they both have an elongate outer ear canal, a muscular gizzard, and complete separation of the ventricles of the heart. ¡§Crocodilians are the most advanced of all reptiles. They are elongated, armored, and lizard-like, with a muscular, laterally shaped tail used in swimming.
Their body temperature reflects the temperature of the surrounding air or water. Turtles date back to around two hundred million years ago. Having over forty nine species of turtles, they can live both in water and on land. The top shell, referred to as carapace, of land a turtle are over-grown and makes the ribs wider. Beneath the top shell is the lower shell, referred to as plastron.
If the environment become too warm, they will shift between the sun and shade (Starr, 2003). Example of ectothermic animals are snakes, lizards and frogs. In conclusion, the four types of thermoregulations that was discussed are poikilotherm, homeotherm, endotherm, and ectotherm. Each of them have their own unique characteristics and their adaptation are mostly regulated by their environment. This is one of the most preferred examples for homeostatis process because it allows that certain organisms to survive in their harsh environment so that their genomic information can be passed from their generation to the next.
Scuba diving is diving with a self-contained underwater breathing apparatus, that is completely independent of surface supply. Providing the diver with the advantages of underwater mobility whilst being able to sustain life at underwater pressures. Embolism results when gasses in the lung expand during ascent and rupture lung tissue, causing air bubbles to enter the bloodstream. The Usage of Nitrox Enriched Air Nitrox is often used in scuba diving, to reduce the proportion of nitrogen in the breathing gas mixture. Reducing the proportion of nitrogen by increasing the proportion of oxygen reduces the risk decompression sickness for the same dive profile.