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Articles 1 - 30 of 69
Full-Text Articles in Animal Sciences
New Species Of Dryolestoid From The Late Cretaceous Allen Formation And Implications For South American Faunal Diversity., Brigid Erin Connelly
New Species Of Dryolestoid From The Late Cretaceous Allen Formation And Implications For South American Faunal Diversity., Brigid Erin Connelly
Electronic Theses and Dissertations
Dryolestoids are extinct cladotherians mammals from the Jurassic and Cretaceous periods. I describe a collection of dryolestoid specimens from the Late Cretaceous localities of Cerro Tortuga (Allen Formation), Anfiteatro 1, and Shining (both La Colonia Formation) from Patagonia, Argentina. Using comparative morphology, I identify a new species of meridiolestidan dryolestoid based on eleven specimens across both formations. The new species’ recovery from La Colonia Formation represents the first dryolestoid connection between the two approximately contemporaneous formations. The species’ morphology may represent an ecological shift within Meridiolestida from insectivory to herbivory, showing a transition in characters between the plesiomorphic sharp-toothed meridiolestidans …
Comparative Energetics Of Mammalian Thermoregulatory Physiology, Ana M. Breit
Comparative Energetics Of Mammalian Thermoregulatory Physiology, Ana M. Breit
Electronic Theses and Dissertations
Endothermy allows species to decouple body temperature from environmental
temperatures but does not equate to endothermic species maintaining those constant temperatures. Instead, heterothermy fluctuating body temperatures, both in and outside of torpor is common and allows endotherms to expand the limits of thermoneutrality. Thermolability is likely to be more common in the tropics and subtropics, where species live within or above their thermoneutral zone. My dissertation research focused on the heterothermic-homeothermic continuum, specifically quantifying where on the continuum different species fall at certain times and why those species have evolved to be at those points. I quantified the thermal profile …
Optimizing Strategies To Hydraulically Plant Atlantic Salmon Eggs Based On Fry Dispersal Patterns, Ernest J. Atkinson
Optimizing Strategies To Hydraulically Plant Atlantic Salmon Eggs Based On Fry Dispersal Patterns, Ernest J. Atkinson
Electronic Theses and Dissertations
The Gulf of Maine Distinct Population Segment of Atlantic Salmon has suffered from habitat loss and exploitation over the last century. Hatchery supplementation has prevented the extirpation of the species, but stocking methods represent tradeoffs between survival, domestication, and logistics. Egg planting, the use of eyed embryos, maximizes natural rearing opportunities which can be important for adaptation. This method, however, is logistically demanding and requires significant labor over large spatial, but short temporal, scales dictated by the ontogeny of the fish. However, the survival and dispersal behavior of Atlantic Salmon fry immediately after emergence from eggs planted in artificial nests …
Relating Predator Community Ecology And Duck Nest Survival In Eastern South Dakota, Samantha R. Fino
Relating Predator Community Ecology And Duck Nest Survival In Eastern South Dakota, Samantha R. Fino
Electronic Theses and Dissertations
As conversion of native grasslands and wetlands to croplands continues in the Prairie Pothole Region (PPR), managers are tasked with maintaining sustainable waterfowl populations. Mesopredator community dynamics is a hypothesized mechanism driving spatiotemporal variation of waterfowl nest survival in the PPR, yet studies often lack detailed information on mesopredator species occurrence and abundance. Therefore, understanding spatial and temporal variation in behaviors of mesopredators provides valuable insights for understanding predator-prey interactions between mesopredators and upland duck nests. Further, differences in a predator community resulting from lethal removal of dominant species may influence composition and space use patterns of subordinate and non-target …
Use Of Hematological Markers To Assess Physiological Condition And Health Status In Free-Ranging Sand Tiger Sharks (Carcharius Taurus), Chestina N. Craig
Use Of Hematological Markers To Assess Physiological Condition And Health Status In Free-Ranging Sand Tiger Sharks (Carcharius Taurus), Chestina N. Craig
Electronic Theses and Dissertations
The contents of blood can provide information about the physiological condition and health of vertebrates. This study seeks to better understand the stress physiology and blood bacteria presence of the sand tiger shark (Carcharius taurus), as sharks are known to have unique physiology and immune systems. In this study the blood metabolites glucose, lactate, and ketones (3-hydroxybuteric acid and acetoacetate), were used to understand how biotic and abiotic factors affect the acute stress response to capture and handling. Metabolite concentrations from blood plasma were analyzed using colorimetric assays. Glucose and ketones showed no significant responses to capture and …
The Effects Of Rising Ambient Temperatures On Thermoregulation And Range Shifts Of Northern Flying Squirrels, Elise K. Gudde
The Effects Of Rising Ambient Temperatures On Thermoregulation And Range Shifts Of Northern Flying Squirrels, Elise K. Gudde
Electronic Theses and Dissertations
Climate change may potentially alter a species’ range distribution and thus the relationship between environmental temperatures and animal performance as a response to climate warming has become an important area of research. Two species of flying squirrel in North America, the southern flying squirrel (Glaucomys volans) and the northern flying squirrel (Glaucomys sabrinus) have undergone northward range shifts, with climate warming being the suspected driver. Because they are nocturnal and tree nesting, flying squirrels may be particularly susceptible to warmer temperatures, as they will experience the highest daily ambient temperatures during their resting phase. I used G. sabrinus as a …
Detection, Occupancy, Abundance, And Mercury Accumulation Of The Alligator Snapping Turtle (Macrochelys Temminckii) In Texas, David Rosenbaum
Detection, Occupancy, Abundance, And Mercury Accumulation Of The Alligator Snapping Turtle (Macrochelys Temminckii) In Texas, David Rosenbaum
Electronic Theses and Dissertations
Land use practices and physical alterations of ecosystems result in habitat loss and fragmentation, while chemical alterations, such as pollutant input, reduce habitat quality and health of exposed organisms. Here, I investigated the effects of watershed- and local-scale environmental variables on the occupancy, abundance, and mercury accumulation of a threatened aquatic species (Macrochelys temminckii, i.e., alligator snapping turtle) within the southwestern periphery of its distribution. Hierarchical modeling suggested the distribution of the species is more affected by watershed-scale land-cover than local habitat, and provided a baseline estimate of average species abundance across its range in eastern Texas. Abundance …
Mortality In Interspecific Hybrids Of Nasonia Vitripennis And Nasonia Giraulti, Bonnie Cobb
Mortality In Interspecific Hybrids Of Nasonia Vitripennis And Nasonia Giraulti, Bonnie Cobb
Electronic Theses and Dissertations
Nasonia is a parasitoid wasp genus that serves as an emerging model for studying speciation due to an incompatibility between nuclear and mitochondrial genomes between sister taxa. Short generation times, easy rearing in a lab setting, producing large amounts of progeny, and whole genome sequencing make Nasonia is an excellent candidate for studying incomplete reproductive isolation. Nasonia have five chromosomes and exhibit haplo-diploid sex determination in which fertilized eggs develop into diploid females and unfertilized eggs develop into haploid males. Recessive phenotypes are hidden in diploid females but are laid bare in haploid males as there is no interaction between …
A Post-Pneumonia Epizootic Evaluation Of The Rapid City, South Dakota Bighorn Sheep Herd, Amanda N. Ensrud
A Post-Pneumonia Epizootic Evaluation Of The Rapid City, South Dakota Bighorn Sheep Herd, Amanda N. Ensrud
Electronic Theses and Dissertations
Pneumonia is a major factor affecting populations of free-ranging bighorn sheep (Ovis canadensis) across western North America. Pneumonia can occur in large-scale epizootics, during which greater than half of the population typically dies. After these epizootics, surviving ewes continue to conceive and bear lambs. However, lamb recruitment may remain low due to periodic or annual pneumonia outbreaks causing high lamb mortality rates, sometimes greater than 90%. Our study focused on the Rapid City, South Dakota bighorn sheep (BHS) herd that has recorded pneumonia-induced population decline since 2009. The first objective was to improve lamb health and survival by identifying and …
Evaluating Avian Use Of Cover Crops In The Corn Belt, Megan Figura
Evaluating Avian Use Of Cover Crops In The Corn Belt, Megan Figura
Electronic Theses and Dissertations
The tallgrass prairie of North America has changed drastically since colonial settlement, with up to 99% of this region converted for agriculture and other land-uses. Concurrent with grassland conversion, grassland birds have experienced the most extreme, consistent, and widespread population declines of any avian guild. Agricultural lands in the U.S. Midwest were able to provide adequate habitat for several bird species until the 1950’s; however, altered and intensified management practices have degraded much of remaining suitable habitat and undermined ecosystem functions. Consequently, many grassland birds have been identified as Species of Greatest Conservation Need (SGCN) in many State Wildlife Action …
Forest Disturbance And Occupancy Patterns Of Carnivores: Results Of A Large-Scale Field Study In Maine, Usa, Bryn E. Evans
Forest Disturbance And Occupancy Patterns Of Carnivores: Results Of A Large-Scale Field Study In Maine, Usa, Bryn E. Evans
Electronic Theses and Dissertations
Understanding trends in the abundance and distribution of carnivores is important at global, regional and local scales due to their ecological role, their aesthetic and economic value, and the numerous threats to their populations. Carnivores in Maine range from the American black bear (Ursus americanus), to numerous native mesocarnivore species, such as American marten (Martes americana), fisher (Pekania pennanti), coyote (Canis latrans), red fox (Vulpes vulpes), bobcat (Lynx rufus), Canada lynx (Lynx canadensis) and to two small weasel species (Mustela erminea and Neogale frenata). …
Population Genetic Analyses Of Arctic Char (Salvelinus Alpinus) Life History Types In Nettilling Lake & Amadjuak River Ecosystem: A Test Of Reproductive Isolation, Chen Liu
Electronic Theses and Dissertations
A great number of studies have identified strong genetic differences between sympatric anadromous and resident populations of Salmonidae. However, Arctic char (Salvelinus alpinus) migratory phenotypes in the Nettilling Lake and Amadjuak River ecosystem in Nunavut, Canada have not been genetically characterized, and it remains unclear if distinct genotypes and phenotypes associated with migratory life history differences are maintained through reproductive isolation, and they have been assumed to be sympatric populations, or co-occurring populations. Co-occurring Arctic char (n=225) were sampled from eleven sites along the Amadjuak River in 2014 and 2015. Twelve microsatellite loci were used to quantify genetic variation among …
Does It Take A Community To Save A Species? Examining The Use Of Community Interactions To Restore Unionid Species At Risk, Roland Adriaan Eveleens
Does It Take A Community To Save A Species? Examining The Use Of Community Interactions To Restore Unionid Species At Risk, Roland Adriaan Eveleens
Electronic Theses and Dissertations
The conservation and restoration of freshwater ecosystems are complex. Knowledge from community ecology, conservation biology, and restoration ecology was integrated to interrogate the role of species interactions involving freshwater mussels (order Unionida) as keystone species. Freshwater mussels require host fish and provide ecosystem functions for other species throughout aquatic and riparian ecosystems, yet conservation efforts remain focused on focal mussel species or host fish associations. My thesis explored species co-occurrences within mussel and benthic macroinvertebrate community assemblages, and systematically reviewed the published literature to assess the breadth and reported effectiveness of mussel restoration. Community analyses confirmed species co-occurrences across environmental …
Environmental Impacts On The Reproduction Of Three Cold-Water Corals, With Implications For Their Vulnerability To Ocean Warming And Climate Change, Julia Johnstone
Environmental Impacts On The Reproduction Of Three Cold-Water Corals, With Implications For Their Vulnerability To Ocean Warming And Climate Change, Julia Johnstone
Electronic Theses and Dissertations
Cold-water corals are important habitat builders in the deep ocean worldwide. Despite being known for centuries, recent technological advances and deep-sea exploration has revealed cold-water corals thriving at depths of up to 6000m. Similar to their warm-water relatives, cold-water corals are hotspots of diversity, with their structures creating habitat for thousands of associated species. Some cold-water corals create bioherms that stretch for tens of kilometers, while others come together to form vast undersea forests. These habitats are often home to commercially important fisheries species, and conservation efforts have recently begun to regulate fishing in cold-water coral ecosystems to protect them …
Using Predator Vocalizations To Deter Raccoon Predation On Nests Of Diamondback Terrapins (Malaclemys Terrapin), Colleen Elizabeth Naeger
Using Predator Vocalizations To Deter Raccoon Predation On Nests Of Diamondback Terrapins (Malaclemys Terrapin), Colleen Elizabeth Naeger
Electronic Theses and Dissertations
No abstract provided.
The Effect Of Bts Induced Inactivity On A Zebrafish Model Of Duchenne Muscular Dystrophy, Sean Driscoll
The Effect Of Bts Induced Inactivity On A Zebrafish Model Of Duchenne Muscular Dystrophy, Sean Driscoll
Electronic Theses and Dissertations
Duchenne’s Muscular dystrophy (DMD) is a congenital disease of the muscle characterized by muscle atrophy, weakness, and a lower quality of life. Often diagnosed in children, it affects about 1 in every 5,500-7,700 males. A patient diagnosed with DMD is often told to avoid physical activities outside the required amount needed to go on with their day in order to preserve the muscle fibers and integrity. Inactivity in a healthy person leads to decreased muscle mass and increased weakening of the muscle, so we questioned if the effects may be exacerbated in a person diagnosed with DMD having already weakened …
Dietary Change Among Canis Familiaris During The Late Ceramic Period On The Maine-Maritime Peninsula: A Case Study From The Holmes Point West Site (Me 62-8), Machias Bay, Maine, Abby E. Mann
Electronic Theses and Dissertations
Archaeological study of Indigenous pasts has been characterized by a focus on objects over people. This study attempts to humanize the past by illuminating human agency in the human-dog relationship through a case study of dog health and diet during the Late Ceramic period (ca. 950 – 450 BP) in the Maine-Maritime Peninsula region. To circumvent the cycle of western knowledge building and marginalization of Indigenous communities, past Wabanaki people and their relationships with dogs are positioned at the center of research questions presented here. Few studies in the Northeast have analyzed dog remains from the Ceramic period (ca. 3050 …
Effects Of Anthropogenic Light And Noise On Anuran Breeding Behavior, Ashley Kobisk
Effects Of Anthropogenic Light And Noise On Anuran Breeding Behavior, Ashley Kobisk
Electronic Theses and Dissertations
The natural environment can be negatively impacted by a variety of human activities, including the production of artificial light at night and anthropogenic noise. Recent studies suggest that pollution from anthropogenic light and noise alters animal behavior. Despite being highly nocturnal and vocal animals, little attention has been given to anurans and the effects artificial light at night and anthropogenic noise have on their behavior. This study investigated the effects of artificial light at night and anthropogenic noise on anuran breeding systems in eastern Texas. Specifically, this study investigated whether (1) artificial light and anthropogenic noise altered calling behavior in …
Sexual Dimorphism Of Thermal Preference In Florida Scrub Lizards (Sceloporus Woodi) And Predicting Response To Climate Change In Two Rare Habitats, Sidney E. Anderson
Sexual Dimorphism Of Thermal Preference In Florida Scrub Lizards (Sceloporus Woodi) And Predicting Response To Climate Change In Two Rare Habitats, Sidney E. Anderson
Electronic Theses and Dissertations
The Florida Scrub Lizard (Sceloporus woodi) is endemic to Florida, where it inhabits fragments of xeric sandhill uplands including endangered long-leaf pine and sand pine scrub habitats. Lizards depend on a predictable range of temperatures to maximize their growth and productivity, and to do so, they shuttle among various thermal micro-environments. Thus, the spatial distribution of temperatures in the habitat is important. Habitats dominated by either high or low extremes of an organism’s preference are energetically costly and dangerous (less optimal), especially to gravid females. This study examines thermal preference of a near-threatened species that also inhabits increasingly rare habitats. …
Predation Threat In A Variable Landscape: Connecting Predation Risk To Nesting Success For The Seaside Sparrow (Ammospiza Maritima Macgilivraii), Corina D. Newsome
Predation Threat In A Variable Landscape: Connecting Predation Risk To Nesting Success For The Seaside Sparrow (Ammospiza Maritima Macgilivraii), Corina D. Newsome
Electronic Theses and Dissertations
Predation, the leading cause of nest-failure in birds, not only exists as a direct threat to nesting success, but may exacerbate other sources of nest mortality. Birds inhabiting Atlantic coastal marshes, such as Seaside Sparrows (Ammospiza maritima; hereafter SESP), are experiencing significant and rapid changes to their habitat, particularly sea level rise (SLR) and encroaching urbanization, that may affect the relative influence of nest predation on overall productivity. For SESPs, SLR presents an inherent threat to nest success in its potential to increase the frequency of nest flooding. In addition to this direct threat, the ability of SESPs …
Assessing Habitat Suitability Of Ribbed Mussels (Geukensia Demissa) In Georgia Salt Marshes By Examining Predicted Mussel Densities And Mussel Population Parameters, William K. Annis Jr
Assessing Habitat Suitability Of Ribbed Mussels (Geukensia Demissa) In Georgia Salt Marshes By Examining Predicted Mussel Densities And Mussel Population Parameters, William K. Annis Jr
Electronic Theses and Dissertations
Geukensia demissa (ribbed mussel) is an ecology important bivalve that has the potential to contribute to salt marsh restoration. Understanding the factors that contribute to the distribution of mussels can help inform managers on choosing locations to optimize the survivorship of mussels in restoration projects. This study sought to model mussel densities across the coast of Georgia and to compare predicted mussel densities with mussel population parameters as means to gauge habitat suitability. Mussel densities were collected through field surveys across a range of salt marshes along the coast of Georgia and were compared with spatial data such as distance …
Residency, Diel Movement, And Tidal Patterns Of Large Juvenile Bull Sharks (Carcharhinus Leucas) In Winyah Bay, Sc, Jeremy Lee Arnt
Residency, Diel Movement, And Tidal Patterns Of Large Juvenile Bull Sharks (Carcharhinus Leucas) In Winyah Bay, Sc, Jeremy Lee Arnt
Electronic Theses and Dissertations
No abstract provided.
Analyzing The Longevity Of Sperm Within The Female Japanese Quail By Assessing Sperm Penetration Of The Perivitelline Layer Under Optimal And Suboptimal Conditions., Garret G. Ashabranner, Joey L. Bray
Analyzing The Longevity Of Sperm Within The Female Japanese Quail By Assessing Sperm Penetration Of The Perivitelline Layer Under Optimal And Suboptimal Conditions., Garret G. Ashabranner, Joey L. Bray
Electronic Theses and Dissertations
After mating, birds have the ability to store semen within the female reproductive tract. The sperm storage tubules will store and subsequently release semen to travel up the oviduct. Sperm cells that make the trek up the oviduct have a chance to fertilize the ovum. These sperm cells will bind to the perivitelline layer of the ovum and hydrolyze a hole in the perivitelline layer, where it has the possibility to fertilize the female sex cell. Analyzing the number of penetration points on the perivitelline layer is an effective way to analyze reproductive efficiency. Many environmental factor has its effect …
Glare Reduction By Dark Facial Markings And Bills In Birds, Clara Lebow
Glare Reduction By Dark Facial Markings And Bills In Birds, Clara Lebow
Electronic Theses and Dissertations
Avian facial plumage, bill coloration, and feather microstructure may serve one or more adaptive functions. Several researchers have proposed that dark eyestripes, bills, and facial masks aid in reducing glare, however, there have been relatively few tests of this hypothesis. Dark facial markings have been shown to have an adaptive glare-reduction function in recent field studies of a few species, but this hypothesis has never been tested in a broad multispecies analysis. It is likely that feather microstructure influences feather brightness and has an effect on the efficacy of glare reduction properties of feathers. I examined the link between dark …
Encephalization In Commensal Raccoons: A Unique Test Of The Cognitive Buffer Hypothesis, Peter M. Anderson
Encephalization In Commensal Raccoons: A Unique Test Of The Cognitive Buffer Hypothesis, Peter M. Anderson
Electronic Theses and Dissertations
This study investigated selective pressures associated with encephalization in mammals and discussed broader implications. Relative brain size as measured by EQ (Encephalization Quotient) was compared between ecological categories. Omnivores had higher average EQ than ecological specialists. Since specialists are disproportionately affected by extinction events, selection for ecological generalism is proposed as encephalization mechanism. This mechanism may reinforce the more widely known Cognitive Buffer Hypothesis (CBH)—the idea that possessing relatively large brains has buffered lineages against environmental change. CBH is tested here by comparing EQs in Procyon lotor (raccoon) in urban and rural environments. CBH predicts that raccoons in the most …
Ontogenetic And Adult Shape Variation In The Endocast Of Tapirus: Implications For T. Polkensis From The Gray Fossil Site, Thomas M. Gaetano
Ontogenetic And Adult Shape Variation In The Endocast Of Tapirus: Implications For T. Polkensis From The Gray Fossil Site, Thomas M. Gaetano
Electronic Theses and Dissertations
Endocranial morphology provides evidence of sensory ecology and sociality of extinct vertebrates. The Earliest Pliocene Gray Fossil Site (GFS) of NE Tennessee features a conspicuous dominance of skeletal elements belonging to the dwarf tapir, Tapirus polkensis. Numerous individuals in one fossil locality often suggests gregarious behavior, but sociality in T. polkensis contradicts behavior documented for extant Tapirus species. I test T. polkensis for variation in sensory and social ecology using computed tomography and 3D digital endocasts from an ontogenetic sequence. I compare the T. polkensis endocasts with extant Tapirus species using Encephalization Quotients (EQs) and 3D geometric morphometrics. Results …
The Potential For Dickeya Dianthicola To Be Vectored By Two Common Insect Pests Of Potatoes, Jonas K. Insinga
The Potential For Dickeya Dianthicola To Be Vectored By Two Common Insect Pests Of Potatoes, Jonas K. Insinga
Electronic Theses and Dissertations
Dickeya dianthicola (Samson) causing blackleg and soft rot was first detected in potatoes grown in Maine in 2014. Previous work has suggested that insects, particularly aphids, may be able to vector bacteria in this genus between plants, but no conclusive work has been done to confirm this theory. In order to determine whether insect-mediated transmission is likely to occur in potato fields, two model potato pests common in Maine were used: the Colorado potato beetle (Leptinotarsa decimlineata Say) and the green peach aphids (Myzus persicae Sulzer). Olfactometry and recruitment experiments evaluated if either insect discriminates between infected and …
Effects Of Energy Development On Movements, Home Ranges, And Resource Selection Of White-Tailed Deer In The Western Dakotas, Bailey S. Gullikson
Effects Of Energy Development On Movements, Home Ranges, And Resource Selection Of White-Tailed Deer In The Western Dakotas, Bailey S. Gullikson
Electronic Theses and Dissertations
Oil and natural gas development has increased in recent years and research is needed to assess potential impacts on white-tailed deer (Odocoileus virginianus) populations. Our objectives were to document movements, home ranges, and resource selection of female white-tailed deer in response to energy development in the western Dakotas. Our study areas included Dunn County, North Dakota, an area with current oil and gas development, and Grant County, North Dakota, and Perkins County, South Dakota, areas without current oil and gas development. We captured and fitted 150 female deer with Very High Frequency (VHF) collars across study sites, and …
The Population Ecology And Behavior Of The Cave Salamander, Eurycea Lucifuga (Rafinesque, 1822)., Joseph Gavin Bradley
The Population Ecology And Behavior Of The Cave Salamander, Eurycea Lucifuga (Rafinesque, 1822)., Joseph Gavin Bradley
Electronic Theses and Dissertations
The Cave Salamander, Eurycea lucifuga (Rafinesque, 1822), is a little-known species, yet a common inhabitant of caves in the eastern United States. Salamanders are often important components of ecological communities and ecosystems, influencing critical processes such as nutrient cycling and community composition through their predation on invertebrates. Cave-dwelling salamanders such as E. lucifuga may thus appreciably influence the relatively simple ecosystems and communities of caves. Any such influence may be particularly important because these habitats and the organisms that reside in them are often of conservation concern. I used non-invasive methods to study the demographics, movements, and habitat selection of …
Unique Osmoregulatory Morphology In Primitive Sharks: An Intermediate State Between Holocephalan And Derived Shark Secretory Morphology, Matthew Eric Larsen
Unique Osmoregulatory Morphology In Primitive Sharks: An Intermediate State Between Holocephalan And Derived Shark Secretory Morphology, Matthew Eric Larsen
Electronic Theses and Dissertations
Discovery of an unusual rectal gland in the Atlantic sixgill shark, Hexanchus vitulus, led to examination of rectal glands in 29 species of epipelagic and deep-sea sharks. Eight of 14 deep-sea species of sharks had digitiform glands that were previously assumed to be characteristic of elasmobranchs (N=281; mean width-length ratio ± SD = 0.18 ± 0.07). Hematoxylin-and-eosin stained sections from deep-sea sharks were similar to those from shallow water sharks. Glands from the family Somniosidae were kidney bean-shaped (N = 3; mean width-length ratio ± SD = 0.46 ± 0.05); whereas those from the families Echinorhinidae and Hexanchidae appeared lobulate …