Person:
Ketten, Darlene

Profile Picture

Email Address

AA Acceptance Date

Birth Date

Research Projects

Organizational Units

Job Title

Last Name

Ketten

First Name

Darlene

Name

Ketten, Darlene
Author's Publications: search.filters.isAuthorOfPublication.2eedce89-03b7-4f62-8027-3caa395bfb09

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    Middle Ear Cavity Morphology Is Consistent with an Aquatic Origin for Testudines
    (Public Library of Science, 2013) Willis, Katie L.; Christensen-Dalsgaard, Jakob; Ketten, Darlene; Carr, Catherine E.
    The position of testudines in vertebrate phylogeny is being re-evaluated. At present, testudine morphological and molecular data conflict when reconstructing phylogenetic relationships. Complicating matters, the ecological niche of stem testudines is ambiguous. To understand how turtles have evolved to hear in different environments, we examined middle ear morphology and scaling in most extant families, as well as some extinct species, using 3-dimensional reconstructions from micro magnetic resonance (MR) and submillimeter computed tomography (CT) scans. All families of testudines exhibited a similar shape of the bony structure of the middle ear cavity, with the tympanic disk located on the rostrolateral edge of the cavity. Sea Turtles have additional soft tissue that fills the middle ear cavity to varying degrees. When the middle ear cavity is modeled as an air-filled sphere of the same volume resonating in an underwater sound field, the calculated resonances for the volumes of the middle ear cavities largely fell within testudine hearing ranges. Although there were some differences in morphology, there were no statistically significant differences in the scaling of the volume of the bony middle ear cavity with head size among groups when categorized by phylogeny and ecology. Because the cavity is predicted to resonate underwater within the testudine hearing range, the data support the hypothesis of an aquatic origin for testudines, and function of the middle ear cavity in underwater sound detection.
  • Thumbnail Image
    Publication
    The Auditory Anatomy of the Minke Whale (Balaenoptera acutorostrata): A Potential Fatty Sound Reception Pathway in a Baleen Whale
    (Wiley, 2012) Yamato, Maya; Ketten, Darlene; Arruda, Julie; Cramer, Scott; Moore, Kathleen
    Cetaceans possess highly derived auditory systems adapted for underwater hearing. Odontoceti (toothed whales) are thought to receive sound through specialized fat bodies that contact the tympanoperiotic complex, the bones housing the middle and inner ears. However, sound reception pathways remain unknown in Mysticeti (baleen whales), which have very different cranial anatomies compared to odontocetes. Here, we report a potential fatty sound reception pathway in the minke whale (Balaenoptera acutorostrata), a mysticete of the balaenopterid family. The cephalic anatomy of seven minke whales was investigated using computerized tomography and magnetic resonance imaging, verified through dissections. Findings include a large, well-formed fat body lateral, dorsal, and posterior to the mandibular ramus and lateral to the tympanoperiotic complex. This fat body inserts into the tympanoperiotic complex at the lateral aperture between the tympanic and periotic bones and is in contact with the ossicles. There is also a second, smaller body of fat found within the tympanic bone, which contacts the ossicles as well. This is the first analysis of these fatty tissues' association with the auditory structures in a mysticete, providing anatomical evidence that fatty sound reception pathways may not be a unique feature of odontocete cetaceans.
  • Thumbnail Image
    Publication
    Deadly Diving? Physiological and Behavioural Management of Decompression Stress in Diving Mammals
    (The Royal Society, 2011) Hooker, S. K.; Fahlman, A.; Aguilar de Soto, N.; Bernaldo de Quirós, Y.; Brubakk, A. O.; Costidis, A. M.; Dennison, S.; Falke, K. J.; Fitz-Clarke, J. R.; Garner, M. M.; Houser, D. S.; Jepson, P. D.; Kvadsheim, P. H.; Rowles, T. K.; Van Bonn, W.; Weathersby, P. K.; Weise, M. J.; Tyack, P. L.; Moore, M. J.; Costa, D. P.; Fernandez, A.; Ferrigno, Massimo; Ketten, Darlene; Madsen, P. T.; Pollock, Nira; Rotstein, D. S.; Simmons, S. E.; Williams, T. M.
    Decompression sickness (DCS; ‘the bends’) is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N\(_2\)) loading during dives. However, recent observations have shown that gas bubbles may form and tissue injury may occur in marine mammals under certain circumstances. Gas kinetic models based on measured time-depth profiles further suggest the potential occurrence of high blood and tissue N\(_2\) tensions. We review evidence for gas-bubble incidence in marine mammal tissues and discuss the theory behind gas loading and bubble formation. We suggest that diving mammals vary their physiological responses according to multiple stressors, and that the perspective on marine mammal diving physiology should change from simply minimizing N\(_2\) loading to management of the N\(_2\) load. This suggests several avenues for further study, ranging from the effects of gas bubbles at molecular, cellular and organ function levels, to comparative studies relating the presence/absence of gas bubbles to diving behaviour. Technological advances in imaging and remote instrumentation are likely to advance this field in coming years.