Skeletal Changes During Whale Evolution

Some information to get you started is that the scientific name for the Blue Whale is Balaenoptera Musculus, Musculus means “little mouse” which is

Killer whales, Orcinus orca, are mammals, that are part of the Cetacea order, the Odontoceti suborder and the Delphinidae family (Ketten, 1997). They evolved from land creatures, requiring a multitude of adaptations so that the transition to water was successful. They live in all oceans, but are most commonly found in cool, temperate waters (Strager, 1994).

A Blue whale (Balaenoptera musculus), which is also known as the great blue whales is a marine mammal that roams in various oceans throughout the world. These mammals are found in all types of bodies of oceans and usually swim in small groups or even at times, alone. They are the heaviest animals to ever exist on earth.

The first ancestor, the Indohyus, was discovered 48 million years ago. Indohyus’ were 4 legged and lived on land, the complete opposite of the modern day whale. Down the timeline to the Ambulocetus, more evolved whales showed higher levels of saltwater oxygen isotopes. This is important because it shows that they spend way more time in the water than their ancestors. Also, it means they lived in a nearshore marine habitat and were able to drink saltwater like today’s whales are able

Dolphins have undergone an interesting history as they evolved from their whale ancestors. Archaeoceti is a parvorder comprising ancient Cetaeca.

Whales have roamed the Earth’s oceans for about 50 million years, they are the largest mammals on the planet, ranging from sizes of 8 feet to 112 feet. There are 86 different species of whale, however they are divided into two groups, the Odontocetes, or toothed whales and the Mysticetes, or baleen whales. Out of the 86 different types of whale, the largest is the blue whale, belonging to the mysticetes family. The largest Blue Whale ever recorded was 111 feet in length and about 173 metric tons, not only is it the biggest whale in the world, it is the biggest animal ever known to have lived.

“The process of evolution can be very slow, and allows living creatures to develop an anatomy that is structured for them to thrive” (Dolphin Evolution). Evolution is the gradual development of a creature, especially from a simple to a more complex organism. Many mammals have evolved from one animal to another. For instance, dolphins has evolved from land animals to ocean animals. All of the dolphins belong to the cetacean family, which also include whales, dolphins and porpoises. Dolphins are now aquatic mammals who are very intelligent and curious. However, what forces made them evolve? And what did Darwin mean by “survive by the fittest”? Or what principles of evolution or survival are at work? (Samantha & Paula)

From the tiny flea to the great blue whale, each animal possesses a unique quality that makes it stand out from the rest. Even if you’re a zoology expert, you might be surprised by some of these 25 amazing facts about animals. Prepare to be astounded by the resilience, physical abilities, and sheer brilliance of these magnificent creatures.

Mammals that have adapted to live in the aquatic environment have many advantages. This means that their habitat is vastly larger than that of terrestrial mammals. They are able to feed, breed and live both in the water and on land. It helps their survival as they are able to avoid predation

Scientists believe that millions of years ago the ancestors of whales and dolphins lived on land-- probably around the time of the dinosaurs' extinction. At some point, dolphins and whales left the land to dwell in water.

As a whale breathes air in through the blowhole at the top of its head, the air enters the lungs, oxygenates the blood and travels through the body to feed all of the tissues. The gases in the air dissolve in the fluids of the body. These gases include nitrogen. As the whale descends deeper and deeper into the ocean, the air has to become more and more compressed. This will force more of the gases to be dissolved into the tissues. If the lungs were really large, more nitrogen (for example) would be able to be contained and then absorbed, which would create toxicity in the body. If the whale ascended too quickly with all that gas absorbed in the tissues and not enough in the lungs, it would lead to the Bends (or decompression sickness).

Cetaceans are fully aquatic marine mammals. There are around 88 different species of cetaceans, which consist mainly of whales and dolphins. Cetaceans evolved many years ago to adapt to their lives in water, forming two limbs into flippers and creating streamlined bodies

Amphibians were the first tetrapod vertebrates as well as the first vertebrates to live on land. During this interval, this lineage of fleshy-finned organisms moved from the water to the land.

A pair of "dolphins" beached in Waveland, Mississippi turned out, actually, to be melon-headed whales. The last time the species was seen in the area was about 40 years ago.

The Elasmobranchs are a subclass of class Chondrichthyes. The Chondrichthyes are classified as the Cartilaginous fishes. Aside from the Elasmobranchs, this class has another subclass named Holocephali which is comprised of the chimaera. The Elasmobranchs are comprised of sharks (Selachii) and the rays and the similarly structured skates (Batoidea) Van-Eyl, S. M., Siebeck, U. E., Champ, C. M., Marshal, J., & Hart, N. S. (2011). There have been fossils of sharks found dating about 400 million years and while there is much data that points to diversification throughout the millennia, skates and rays only appear about 200-100 million years ago (Wilga 2005). The Elasmobranchs are classified apart from other fishes despite their external similarities due to several key structural differences. One of these is the absence of a swim bladder. True fishes use this gas filled organ to control their buoyancy without having to waste physical energy on maintaining the desired depth in water. Instead, the Elasmobranchs have developed especially large livers that can produce and withhold large amounts of oil. This is especially evident in the sharks where the liver can sometimes weigh up to 20 percent of their total body weight.