Development and Composition of Middle Ear Structures of Balaenopteroids

During whale evolution many skeletal changes occurred, the whale started out as an animal that mostly hunted and existed on land and slowly evolved. The skeletal system of a whale got much longer, its body developed new structures to help increase its survivability such as its flippers.

The evolutionary path of a whale is a fascinating process of a terrestrial mammal that evolves into a marine mammal. This evolutionary path started with one of the earliest ancestors called “Pakicetus”. A Pakicetus was discovered to be a land animal with four legs that had teeth as carnivores. It skull structure was long, but this organism didn’t look like any marine animal. The scientist then discovered that on the skull’s ear region it was surrounded by a bony wall. This feature on an organism only was distinct from one type of species, scientist discovered that this animal “Pakicetus” was an ancestor of a whale. By comparing the early whales Pakicetus to the next generation of ancestors Ambulocetus, the Ambulocetus whale looks more like

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.

There is no doubt that humans have always been intrigued with the majestic beauty of the large giants found in all of the world’s oceans. Whales and people have had a long history together, marked by many turns of events.

The ear bone serves as more than a 2 inch bone but the eternal soul of a whale and the way it persists its life inside the gray sea. The ear bone is so small that “our

Recent evidence suggests that whales may not have always inhabited the oceans. Bones of an ancient ancestor of modern day whales, the Basilosaurus, were discovered in Pakistan that suggest whales evolved from a wolf-like creature. This genus of an early whale lived 34-40 million years ago in the late Eocene. These fossils show many different features in common with both modern day whales and modern day land mammals. Since the discovery of these bones, many other evidences show that whales are a likely descendant of the Basilosaurus through many different ways, such as embryologic comparison and DNA testing. Whales aren’t the only suspected descendants

In marine mammal biology a large portion of the study is dedicated towards the study of adaptations to the marine environment. By comparing the anatomy between marine mammals and terrestrial mammals scientists can better understand evolutionary history of how these two categories of mammals diverged from one another. The purpose of this lab was to study the anatomy of different marine and terrestrial mammals and compare their similarities and differences in homologous traits and how adaptations were made specifically for marine mammals to survive the aquatic environment. To accomplish this bones of different species of animals were studied since these structures serve as the basis for comparison across species as well as an indicator of each animal’s individual morphology and physiology. A standard measurement protocol for bones of particular regions of the skeleton was established with emphasis on length versus width ratio as well as it’s overall size relative to its more complex features, i.e. humerus length versus hand length.

II. the second reason is because the whales do a lot of turning since they cannot swim in a straight line as they do in the wild, thus bending the fin.

Killer whales are apex predators, lacking natural predators of their own, and inhabit all of the worlds oceans and most of our seas. They vary broadly in behavior, diet, and communication patterns. There are three main sympatric ecotypes of killer whales present in the Pacific Northwest, known as “resident”, “transient” and “offshore” killer whales. Of these, the resident whales of the Salish sea have been by far the most heavily studied. Their prey is salmon, chinook salmon in particular, and they hunt cooperatively. The resident pods are divided into “northern residents” and “southern residents”, the latter being comprized of three pods (J, K, and L). These three pods are well researched, as their markings and distinct calls make identification extraordinarily accessible to human scientists. Orca are distinct among mammals for the long post-reprodutive life of female orca, who provides extensive parental care even after menopause. Numerous studies have shown a clear correlation between the mother’s survival and the offsprings fitness. This paper will explore the matrilinal social structures of Puget Sound’s orcas to assess the evolutionary advantages to close mother-son relations. In particular, it will examine the difference in behavior of female and male offspring upon reaching sexual maturity, and relate this to similarities or differences in parental care output from male and

Blackfish, a whistleblowing documentary on the ethical and moral misconduct of SeaWorld, has shown the impact captivity has put on Orca whales. Throughout the film we see male and female whales performing, beaching into shallow pools to wave or blow water on the audience and trainers. But something that is commonly overlooked is the whale’s collapsed dorsal fin. Dorsal collapse is caused by the whale surfacing too much and for a long period of time. It is hypothesized that the

The blue whale uses baleen in order to filter the speech. The blue wales are the largest vertebrate animal. In a study that was reported on May 24 in Proceedings of the Royal Society B, Nicholas Pyenson, the museum's curator of fossil marine mammals, and collaborators Graham Slater at the University of Chicago and Jeremy Goldbogen at Stanford University, went back and found the evolution of the size of whales in over thirty million years of history. They discovered that the huge whales showed up along multiple branches in the family tree roughly two to three million years ago. A reason for whales having those bigger body sizes is that by the increase of ice sheets located in Northern Hemisphere, whales had to change the way they ontaimed food

The relationship between the mass of the ossicles and tympanic plate area in the remingtonocetid and protocetid is comparable to the ear anatomy found in modern whales. The odontocete transmits sound by means of a large mandibular fat pad and received by the tympanic plate. Sound passes through the odontocete middle ear by means of two lever-arm systems, and the freely suspended involucrum forms the axis of one of these. In contrast, the pakicetids retain the land mammal morphology of the mandible, remingtonocetids and protocetids have a large mandibular foramen that indicates that the mandibular fat pad was present, and that the tympanic plate was functional during underwater hearing. The contact between periotic and tympanic bones in remingtonocetids

The Sperm whale is one the largest predators that inhabits the northern, southern hemisphere, and all parts of oceans. The animal can often be found swimming throughout the waters of the Galapagos Islands. It holds the title of being the largest toothed whale, growing an approximate 40-60 feet in length. The animal is also identified by its unique brown and blue-gray skin color. The Sperm whale’s squared shaped head is the most and largest identifiable feature, while containing underwhelming eyes. The name “sperm” whale derives from an organ inside the mammals large head called the spermaceti organ. The Sperm whales uses its unique features to communicate through echolocation by maneuver its way through the ocean to find prey and potential

Whales are descended from large hoofed predators called mesonychids in the Pakistan area. While seals and walruses descended from a bear like ancestor, the ursoids. (Rybczynski, Dawson, and Tedford 2009) In addition the carnivores and ungulates had long since separated before the convergent evolution that lead to whales, seals and walruses to move back to the ocean. (Prothero 2014) The predatory nature of carnivore that leads them to hunt their prey may also play a part in differentiating these mammals. They hunt animals that may live in the sea or on land such as the penguin and must be adapted as such to follow their prey from sea to land in order to catch it. During the evolution of these animals hair was lost in the whales but retained in the seals and walruses another reason this may have happened is because some seals and walruses eat the mussels, clams and other bivalves that live on the ocean floor. Hair in the form of whiskers or vibrissae that is present in seals and walruses serves a mechanoreception role. They assist in finding food such as mussels and clams on the ocean floor. These vibrissae have a sensitive innervated sinus area that allows the vibrissae to be used as a sensory organ rather than for thermoregulation as the rest of the body fur is used. It may be that the body fur remains because of these vibrissae. If the seals and walruses were to begin losing the fur on their body as insulation and to spend more time in the sea than they could also risk losing the vibrissae that assists them in finding food below the ocean surface since it too is a type of hair. (Maderson

A whale fall occurs when the carcass of a cetacean sinks and settles on the deep sea floor. As it decays and degrades, it provides a source of nutrients for surrounding deep-sea marine life. Stages of decomposition of the cetacean are represented by the presence of different species feeding on the carcass. (Amon et al.) The carcass is first stripped of its soft tissues by sharks and crustaceans. This is known as the mobile-scavenger stage, and it can last from 4 months to 2 years. (Amon et al.) The second stage is called "an enrichment opportunist stage". During this stage, the skeletal remains of the carcass and the nutrient-rich sediment surrounding it play host to large masses of heterotrophic fauna. The fauna feeds on the remaining soft