How is order cetacea organized

All whales are part of the order of mammals known as Cetacea. This family also includes dolphins and porpoises. Cetaceans are marine mammals of the order Cetacea which includes whales, dolphins and porpoises.

Toothed whales are in suborder Odontoceti, baleen whales are in suborder Mysteceti. Delphinadae in the order of Cetacea- whales and whale-like Marine Mammals. Log in. Add an answer. Want this question answered? Study guides. AP Human Geo Unit 3 11 cards.

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Hepatic lipidosis in very young animals is considered physiologic Jaber et al. In these cases, the liver is diffusely pale tan and waxy.

Microscopically, the hepatocytes are swollen with clear cytoplasmic micro and macrovesicles. In pathologic conditions, there may also be compression of the sinusoids and bile canaliculi with cholestasis. Venn-Watson et al. A Typical gross presentation is an enlarged, pale liver, often with rounded edges. B There is diffuse expansion of hepatocytes with cytoplasmic clear vacuoles. This change may be physiologic in neonates but is also seen as a pathologic change in association with inanition.

Iron overload disease has been described in captive bottlenose dolphins. Histologically, livers demonstrate accumulation of iron in hypertrophied Kupffer cells as well as diffuse cytoplasmic iron accumulations within hepatocytes.

The cytoplasmic granules are positive with Prussian blue staining. In the absence of hemochromatosis hepatic necrosis, hepatitis and fibrosis , which is very rare, the diagnosis of hemosiderosis is appropriate. The condition has been associated with diabetes and metabolic syndrome a condition in humans and suggested in dolphins associated with hepatic iron accumulation and resting hyperglycemia.

The etiology and pathogenesis of this condition are poorly understood; however, chronic inflammation, iron sequestration secondary to acute sepsis, excessive dietary iron consumption or supplementation, emaciation, inborn errors of metabolism, and a maladaptive type syndrome may be considerations Venn Watson et al. Renal calculi associated with ammonium urate nephroliths Fig. A study by Smith et al. The presence of nephroliths in advanced cases is associated with clinical hematuria and nephritis as well as secondary renal atrophy.

When dislodged from the kidney, stones can obstruct the ureters or urethra and cause subsequent hydroureter, hydronephosis, as well as possible unilateral shutdown of kidneys. The liths present as miliary concretions scattered within the renal parenchyma. They can grow to 1—2 cm in diameter and are associated with hematuria, nephritis, ureteritis, and ureteral obstruction. Massive urolithiasis of the penile urethra was reported in an adult pygmy sperm whale.

Histologically, there was moderate multifocal to coalescing plasmacytic balanitis and penile urethritis. No associated bladder or kidney damage was identified Harms et al. We have seen a case of vaginal struvite urolithiasis in a common dolphin.

While these cases are uncommon, they demonstrate the need for urolith composition analysis to better understand the pathogenesis of the condition. Struvite urolithiasis is likely related to urinary tract infection as opposed to a metabolic etiology for the ammonium urate stones. A lysosomal storage disease has been seen in multiple beluga whales Fig. The condition is associated with reduced cognitive function.

The lesions include neuron expansion and filling of the neurons with lysosomal lamellar bodies. To date, affected animals have all been adults.

Investigations focus on determination of the enzyme deficit and determination of the etiology as genetic or acquired. A Neurons are distended with granular cytoplasmic content and nuclei are marginated. B Storage material consists of lysosomes converted into concentric lamellar bodies, scanning electron micrograph.

As with many animals, amyloidosis occurs in cetaceans. The product is most likely AA amyloid and reflects part of the inflammatory process. Amyloid can be found expanding the vascular walls of organs throughout the body. It has been specifically described additionally in the corticomedullary regions of the kidneys, around acini of the palatal salivary gland and the thyroid gland Cowan, Harmful algal blooms HABs include a number of toxins that are elaborated by predominantly free swimming unicellular dinoflagellates Table These organisms occur in deep offshore waters and near-shore bays, lagoons and estuaries.

As part of their life cycle, dinoflagellates can sexually reproduce, and then encyst for varying periods of time on substrates, and under appropriate environmental cues they reemerge and produce toxins. The geographic and ecologic distribution of these organisms parallels those of cetaceans and, depending on location as well as species of dinoflagellate and toxin produced; blooms can result in significant mortality events involving marine mammals, birds, fish, and invertebrates Landsberg, Terrestrial species, including man, can be similarly affected; the importance of algal blooms is universal.

It is important to note that toxin levels can vary between isolates within a bloom and not all algae recovered from a bloom may produce HABs. From a pathologic perspective, mass strandings of cetaceans alone or in combination with other aquatic or avian species should prompt an inquiry into a HAB event with collection of appropriate diagnostic and environmental samples. There are few pathognomonic lesions related to HAB exposure in cetaceans and sublethal, long terms effects are largely unknown.

Some dinoflagellates bioaccumulate or concentrate in invertebrate or fish foodweb prey resulting in more protracted strandings, often with supervening or secondary conditions.

Other toxins can be inhaled or ingested and are directly lethal, resulting in a pulse of mortalities. The life cycle and inciting causes of HABs is still under intensive investigation. Saxitoxins are neurotoxic and effect voltage sensitive sodium channels resulting in impaired nerve impulse propagation and paralysis.

A disproportionate number of animals that present with evidence of ship strike or entanglement have detectable levels of saxitoxin and domoic acid; however, the contribution of these toxins to predisposing animals to vessel or other anthropogenic impact remains unknown.

Karenia brevis has a geographic distribution limited to the Gulf of Mexico, Atlantic coast of Florida and the Caribbean. As the organism is unarmoured, it tends to be more pleomorphic and labile; toxins are released on rupture of the cell membranes. The pathogenesis of brevitoxicosis has been attributed to prolonged opening of voltage gated sodium channels in neurons.

Manatee die-offs have been attributed to ingestion of contaminated seagrass. Sporadic large scale stranding events with bottlenose dolphins have been associated with ingestion of heavily contaminated menhaden and aerosol exposure. Aerosolization and inhalation of the toxin is associated with pulmonary and nasopharyngeal edema and hemorrhage as well as multisystem congestion. Upper and lower respiratory tract lesions may be attributed to direct chemical irritation.

Immunohistochemistry demonstrates brevitoxin in pulmonary alveolar lymphocytes and histiocytes as well as in pulmonary lymph nodes. Localized immunosuppression has been postulated as a contributing factor in secondary infections Twiner et al. While domoic acid has been detected in the gastrointestinal contents and urine of a number of cetaceans, a direct causal link to clinical disease and pathology has not yet been resolved. Based on extrapolation from California sea lions, acute to subacute gross lesions may include pyriform lobe necrosis, myocardial degeneration and necrosis, pulmonary edema with occasional pneumonia, gastrointestinal hemorrhage, and reproductive failure; chronic lesions may include hippocampal atrophy and emaciation.

Degenerative cardiomyopathy with pericardial serous effusion has also been reported with acute and chronic manifestations of domoic acid exposure. Microscopically, the acute phase is characterized by multifocal myocardial cytoplasmic vacuolation with variable interstitial accumulation of edema fluid.

With more advanced lesions, there was more generalized myocardial vacuolation with multifocal necrosis, interstitial fibrosis, and scant mononuclear infiltrates with replacement of myocardial fibers by adipocytes. Cetaceans are particularly vulnerable to the effects of oil spills , which may occur as large scale catastrophic events such as the Deep Water Horizon or Exxon Valdez spills, or smaller and often recurrent localized spills, such as with industrial sites.

Nevertheless, even small regional spills may pose a risk if critical habitats are involved, particularly to threatened or endangered populations. Exposure may be through direct contact with the skin, eyes, oral cavity, blowhole, or through ingestion and prey contamination so an awareness of pre-existing stressors in the habitat is essential. The lack of baseline data on ecosystem components, animal health, demographics, and population trends within an oiled area may significantly impede interpretation of pathology and ancillary diagnostic findings and confound delineation of long term lethal and sublethal effects of spills.

Although oil exposure laboratory studies were conducted in the s there are few investigations to assess the pathogenesis of exposure.

Moreover, as petroleum products may include a number of inorganic and organic compounds, it is difficult to extrapolate the effects of one spill to another. As a result, the pathogenesis of oil exposure is often delineated from review of findings with oiling spill events.

In the Deep Water Horizon spill, adrenocortical atrophy, pneumonia, and reproductive loss where significant findings in exposed animals and long term follow up studies may provide valuable insights into the consequences of exposure and population recovery. Detection of visible oil on the surface or within the upper respiratory tract or digestive system should prompt notification of appropriate regional and national authorities and, if the scale of the spill is sufficient, an Emergency Response with Incident Command Activation may occur.

Venn-Watson, Although banned in many regions of the world, persistant organopollutants POPs Table This phenomenon is due to aerosolization and widespread dispersal, environmental persistence, and longevity of many cetacean species.

Individual and synergistic effects of POPs may potentiate toxicity of some compounds. Although numerous hematology, clinical chemistry and in vitro and in vivo immune function studies have been conducted in cetaceans and surrogate pinnipeds, there are few descriptive gross or histopathology descriptions. In addition to impacting immune function, endocrine disruption also occurs.

Long term necropsy results linked to contaminant loads of stranded cetaceans have been analyzed and identify a reduction in splenic and thymic lymphoid populations with increasing POP levels and immunosuppression is inferred. However, it is important to place contaminant loads in context of post mortem state and nutritional status of the animal as artifactual increases may occur with peripheral mobilization of adipose tissue and post mortem dissolution of fat stores.

Environmental accumulation of heavy metals by cetaceans has long been recognized with significantly increased levels of methylmercury identified relative to terrestrial species Table Cetaceans have protein complexes metallothioneins and possibly other chelators that bind copper, zinc, mercury and selenium, and sequester metals in the liver and skin with little to no untoward effect.

Elevated methylmercury is implicated in peripheral and central neuropathies in terrestrial species and lab animals, but there is no indication of similar changes in cetaceans to date.

In a case series of South Australia adult bottlenose dolphins, increased liver, cadmium, copper and zinc were associated with renal pathology Lavery et al.

Lower mineral densities of vertebrae were noted in some animals, but not statistically associated with liver metal concentrations, and may reflect impaired renal function. Multiple single cases of aberrant white coloration in cetaceans have been reported but genetic analysis has not been reported. Overall, 21 species of whales, dolphins, and porpoises have been observed with anomalously white individuals.

The etiology of this coloration is typically presumed to be genetically based albinism. A single case of a white killer whale was attributed to congenital Chediak-Higashi syndrome Taylor and Farrell, Cardiac anomalies reported are diverse. These include transposition of the pulmonary artery and aorta, as well as a ventricular septal defect VSD , persistent ductus arteriosus PDA , atrial septal defect ASD , and right ventricular hypertrophy RVH and subvalvular pulmonic stenosis with a hypoplastic pulmonary artery and mitral valve Powell et al.

The thyroid glands of cetaceans are distinctly lobulated. Lobulation increases with age. The average follicle diameter of the thyroid gland in wild dolphins is larger than that of captive dolphins. Congenital hyperplastic goiter has been associated with perinatal captive bottlenose dolphin deaths Garner et al. Histologic changes included reduced follicular luminal diameter, markedly reduced or absent luminal colloid, hypertrophy of follicular epithelium, micropapillary proliferations, and follicular dysplasia.

Skeletal malformations including craniofacial abnormalities such as prognathism, brachygnathism, incomplete separation resulting in a double-faced monster, and scoliosis have been reported Eissa and Abu-Seida, Care must be taken when diagnosing skeletal changes because early infections and traumatic events can cause skeletal changes in very young calves Fig.

Many alterations in bones such as incomplete fusion of the dorsal processes of cervical vertebrae occur with great variety in severity.

Spina bifida in humpback whales is reported with large gaps of multiple cervical vertebrae Groch et al. In killer whales, the same lesion has been seen but has only been reported to impact single cervical vertebrae with dorsal gaps varying from less than 1 to 4 cm Fig. In both species, determination of clinical impact involves assessing the entire skeleton to determine the number of animals within populations that have these changes. A The animal has pronounced downward and lateral deviations in the vertebral column.

B The vertebral changes may be congenital but early trauma to the spine can cause similar vertebral damage. Computed tomography reconstruction. The animal is robust so an inability to catch prey is unlikely associated with this lesion. This congenital defect is similar to the changes seen in spina bifida but likely was not associated with clinical disease. Much more severe lesions have been reported in humpback whales that lived to adult ages.

Multiple age-related and degenerative changes can be seen in cetaceans. Cardiac, dental, ocular, musculoskeletal, renal and endocrine geriatric conditions have been described. Cardiac disease is very common in both captive and free ranging aged cetaceans St. Leger, pers. Changes include multifocal myocardial degeneration and fibrosis, endocardiosis, valvular fibrosis, papillary fibro-elastomas, mitral leaflet thickening, and left ventricular hypertrophy.

Atherosclerosis is uncommon but has been seen in both captive and free ranging bottlenose dolphins. Degenerative arthritis, spondylitis, and spondylosis occur and are sometimes linked to inanition perhaps secondary to reduced mobility. However, they can also occur unrelated to the proximate cause of death. A holistic evaluation of cases helps to keep pathologic findings in perspective.

Tooth wear, fracture, laxity, and attrition are associated with advanced age in many odontocetes Fig. The limited or lack of enamel covering odontocete teeth increases their vulnerability to wear and damage. As patterns of dental wear in the killer whale can reflect dietary specializations elasmobranchs versus salmonids or other marine mammal prey species and learned behaviors, tooth wear is not always the best indicator of age in some odontocete species.

A Normal conical teeth in the bottlenose dolphin. Teeth are present in both jaws and interdigitate. B Tooth wear in the lower jaw of a geriatric bottlenose dolphin. Teeth are worn to the level of the gingiva. Wear and breakage of teeth are not uncommon in aged odotocetes. Both adenomatous and cystic thyroid changes are common in older bottlenose dolphins and are generally considered incidental, geriatric lesions.

Changes from mild to severe adenomatous thyroid hyperplasia are commonly seen in beluga and harbor porpoises. In beluga, the total volume of the lesions adenomatous hyperplasia is also positively correlated with age Lair et al. These changes have not been sufficiently investigated to determine an etiology or the physiologic impact, but may have important implications when assessing contaminant loads on thyroid hormone levels or gene expression. Adrenal gland hyperplasia is a common change in older delphinids Fig.

It is seen in both free-ranging and display animals and consists of variation in the dimensions of the adrenal gland corticomedullary ratios. Increased thickening associated with either diffuse or nodular cortical, medullary, or extracapsular hyperplasia as well as cortical cyst formation are recognized in some species Lair et al.

The zona fasciculata and glomerulosa are primarily expanded but all three cortical zones can be involved. Medullary expansion may be difficult to distinguish from pheochromocytomas except that cells demonstrate no atypia or increased mitoses. Chlorinated hydrocarbons as a cause for this lesion have been investigated; to date a link has not been found Kuiken et al.

In general, adrenal hyperplasia and cyst formation are not associated with systemic pathology. They may represent compensatory physiology adaptations and typically appear incidental with few sequelae. This is in contrast to adrenocortical atrophy, which has been reported in animals exposed to petroleum products and likely has profound effects associated with hypoadrenocortism, possibly predisposing or exacerbating secondary bronchopneumonia in affected animals.

Irregular expansion of all layers of the adrenal cortex is present and more pronounced on the right side of the gland. The hyperplastic cortical change bulges at the cut surface. Cardiomyopathy CMP was first described in pygmy and dwarf sperm whales in from the southeastern United States Bossart et al.

This condition is seen in animals from both the Atlantic and Pacific Oceans. Cardiomyopathy and myocardial degeneration MCD lesions are identified predominantly among adult whales. The etiopathogenesis remains unknown but investigations are ongoing. Case evaluations suggest this is a chronic and progressive disease initially presenting as myocardial degeneration and advancing to dilated cardiomyopathy Bossart et al.

Gross findings include enlarged hearts with pale, dilated right ventricle and thin interventricular septum Fig. The condition presents as both a hypertrophic and dilated cardiomyopathy—with dilation of the right ventricle an impressive final stage of cardiac degeneration.

Systemic lesions associated with the cardiomyopathy have not been recorded. Microscopically, lesions are characterized by moderate to extensive myocardial cellular degeneration, including anisokaryosis with karyomegaly and nuclear rowing as well as myocardial atrophy and loss. There is concurrent interstitial edema and fibrosis. Infrequently, cases have limited associated mononuclear myocarditis.

As expected, secondary concerns like pulmonary and hepatic congestion are common. The heart is diffusely enlarged. Both ventricles are dilated with thin and flabby walls. Human interactions are a significant contributor to mortality in marine mammals; we continue to have long term impacts on marine mammal population status, recruitment and declines.

Unfortunately, without direct field observations or photodocumentation for confirmation, many cases of human interactions are defined as probable or suspect, which may have important implications from a management, enforcement and legal perspective. Moreover, post mortem change autolysis , scavenging and mutilation can impede recognition and interpretation of gross and microscopic findings in examined animals.

However, advanced imaging studies, chemical analysis of gas emboli, and an increasing knowledge about sharp and blunt force injuries, have all contributed significantly to our improved detection and confirmation of anthropogenic insults. It is important to note that these categories are not mutually exclusive and detection and interaction of more than one entity may occur.

Conversely, a single insult may result in multiple pathologic manifestations. As these incidents may trigger regulatory enforcement or legal investigation, review and use of appropriate forensic diagnostic protocols is imperative.

Moore et al. The most common anthropogenic activities associated with this process include deployment of mid-range tactical naval sonar and net entanglement due to fisheries interaction resulting in abrupt ascent from depth to the surface.

With acute presentations, gas bubbles may be seen in the mesenteric Fig. Associated hemorrhage is most commonly identified in visceral pleura, epicardium, and acoustic fat. Histopathology typically features occlusion and variable vascular distention by clear microcavitations with acute perivascular hemorrhage and occasional infarction Fig.

Should animals survive the initial insult, lesions may resolve through vascular resorption and exhalation or offloading of gases. These cavitations are most commonly recognized within the liver, kidney, spleen, and stomach wall. Dysbaric osteonecrosis has also been reported in larger cetaceans. In the past, gas production associated with putrefaction, and hemorrhage associated with substrate in live stranded animals may have confounded diagnoses of decompression disease; however, with computed tomography imaging studies and mass spectrophotometric analysis of gas samples, nitrogen may be differentiated from those gases attributed to decomposition artifact.

A Variably sized gas bubbles are present in the mesenteric veins. B Multifocally, the hepatic parenchyma is replaced by clear spaces with no defined capsule, inflammation or gas forming bacteria. Similar spaces often contain hemorrhage. High pressure blast and sonar related pathology represent a spectrum of barotrauma. Due to the unique physical properties of the aquatic environment and substrate, lesions in cetaceans are typically more profound in aquatic than in terrestrial mammals.

With detonation of an explosive, there is rapid conversion of the liquid or solid to a gas under high pressure and temperature, which generates a blast front and immediate increase in underwater static pressure.

This energy is transmitted and propagated radially as alternating positive and negative pressure waves. On impact with an animal, there are implosive and pressure differentials, which can generate up to a ninefold increase in pressure. In contrast to detonations on the ground or in the air, underwater explosions are more lethal due to the incompressibility of water, resulting in shock wave propagation up to three times farther than on land, as well as reflection of shock waves along the substrate and air surface interface resulting in more complex blast waves Cox et al.

Pathology related to direct exposure to blast waves is contingent on the magnitude of the explosion, distance and direction of travel of the animal from the blast, and environmental surroundings sloping substrate versus underwater canyons.

Typically, the respiratory, alimentary, circulatory, and auditory systems are involved. On gross examination, hemorrhage may be apparent in the trachea and lungs with pulmonary hematomas, edema, and emphysema tend to be more pronounced on the side of impact. Pulmonary rents with pneumothorax or hemothorax may also occur and microscopically, bronchoalveolar spaces may have frank hemorrhage admixed with exfoliated type I pneumocytes and rafts of detached and aspirated ciliated respiratory epithelia.

With shearing of blood vessels in the lung and blubber, intravascular gas and fat may be apparent and embolization may further compromise homeostasis.

Although the blast wave may impact the abdomen with no apparent external effect, due to gas content within the lumen of the gastrointestinal tract, this system is particularly prone to injury. Gross lesions may include segmental hemorrhage and tearing or perforation of different levels of the digestive system. Ear pathology may include peribullar hemorrhage and fractured tympanic bullae Jepson et al. Recent advancements in acoustic mapping of the cochlea have provided valuable insights to potential sources of acoustic injury.

If ears are harvested and perfused within 18—24 h after death, ultrastructural evaluation of stereocilia and immunofluorescence studies of afferent nerves may provide further evidence of barotrauma.

With any suspect barotrauma related injury, examination of acoustic fats, auditory canals, eyes, and nasal sinuses should be undertaken. Over the last 60 years, advances in vessel design and operating speeds of 14—15 knots or more have been associated with a significant increase in dead floating and live moribund whales with catastrophic lesions consistent with ship strike.

Although small cetaceans and larger whales can be impacted, larger slower moving whales tend to be more frequently involved, particularly when congregated in shipping lanes. Depending on the point of contact with the vessel, animals may present with blunt force or sharp injury that may be directly lethal or contribute to sustained injuries, which may resolve or can persist for extended periods of time.

Case definitions and examples of traumatic lesions are available Moore et al. Although animals affected with blunt force injury may have no apparent external lesions, on reflection of the skin and blubber, subcutaneous hemorrhage and edema at the impact site is usually noted.

If the fibroelastic sheath is intact, focally extensive bulging may be observed and on incision, massive hematoma formation with shearing and necrosis of the subjacent skeletal musculature may be evident.

Rupture of the sheath at the time of impact is more typically associated with extensive subcutaneous hemorrhage, which may track dependently in the hypodermis. Inspection of the abdominal and thoracic cavities may also reveal organ herniation, transposition, rupture, and associated hemorrhage.

Histologicaly, acute myocellular degeneration and necrosis with edema and hemorrhage at the impact site and in muscle samples remote to the site of impact are seen and flocculent, granular, discoid and hyalinized segmental myodegeneration are attributed to agonal catecholamine surge. Fat embolization may be apparent in the pulmonary and renal microvasculature.

Depending on the circumstances, animal impacts with stationary structures, such as piers, moorings, wind farms or tidal hydroelectric turbines, may present with similar gross lesions to those of ship strike Moore et al. In contrast to blunt force injury, animals with propeller injuries have incised and percutaneous wounds that may be curvilinear to sigmoidal, linear, or fenestrated.

Catastrophic injuries are associated with incision into the thoracic or abdominal cavities as well as in those cases with amputation of flippers, fins, or even the peduncle. Involvement of larger caliber blood vessels will result in hypovolemic shock and acute death. Histopathology of the wound margins typically feature subcutaneous edema, hemorrhage, shearing at the site of impact, necrosis and retraction. As these wounds are exposed to the marine environment, imbibed water results in dissolution of erythrocytes, tissue maceration and leaching as well as microbial and ciliate colonization and proliferation.

In nonlethal cases, wound healing may resolve with primary and secondary intention repair. Kelp gulls normally scavenge sloughed whale skin. However, an unusual form of kelp-gull predation of skin in living, free-swimming whales that was first noted in the s has become a locally important problem.

Adult whales have developed several strategies to avoid gulls, for example by keeping their backs under water; calves that have not developed this behavior remain highly vulnerable. The attacks can last for hours at a time and interfere with normal calf resting and nursing. Gull harassment is considered a possible contributing factor in calf mortality McAloose et al.

Skin wounds can vary in size from small, focal lesions covering approximately 0. The wound patterns vary from round to oval and often coalesce. Histologically, the injuries exhibit dermal congestion, suppurative dermatitis and panniculitis, necrotizing vasculitis and vascular thrombosis.

Two calves with wounds forming discrete rhomboid shapes have been described. Bacterial culture and PCR confirmed Erysipelothrix rhusiopathiae from lesions in these two calves Fiorito et al. However, these were isolated cases and bacterial, viral or other infectious diseases that predispose the skin to predation have, to date, not been identified. Southern right whale adult female and calf with dorsal skin wounds typical of kelp gull predation.

The wounds are much more extensive in the calf than the adult. A final traumatic condition of note is the effect of cetacean on cetacean trauma. Attacks on porpoises by bottlenose dolphins have long been recognized in the United Kingdom Ross and Wilson, and are increasingly seen on the Pacific coast of the United States. In these cases, harbor porpoises are pursued and killed but not eaten by bottlenose dolphins. Lesions include massive blunt force traumatic lesions, such as hemorrhage, bruising, and bone fractures with or without abundant skin lacerations from teeth rakes.

Infanticide has been reported in bottlenose dolphins and killer whales. Gastritis and gastric ulcerations impact both captive and free-ranging cetaceans. Parasitic infections are often associated with crateriform ulcers in the nonglandular compartment of the stomach see the parasitic disease section ; however, many cases of gastritis and gastric ulceration are not attributed to helminths. Helicobacter cetorum has been identified in numerous delphinid species with gastritis Davison et al.

Histopathology reveals mild to moderate lymphoplasmacytic gastritis in the superficial mucosa of the main and pyloric compartments with superficial to deep ulcerations and occasional hemorrhage.

Ulceration in the pylorus can perforate and result in fatal chemical or septic peritonitis. Spiral to fusiform bacteria have been detected in the gastric mucosa by Warthin Starry staining. Despite these reports, the role of Helicobacter spp. Geraci associated non-parasitic gastric ulcerations with consumption of high levels of histamine from fish. The possibility of physiologic or psychogenic stressors related to social dynamics or environmental concerns in the development of gastric ulcers in wild or display animals cannot be discounted.

Bycatch refers to the entanglement of cetaceans in fishing gear and affects both small and large cetaceans worldwide. It is considered the most significant threat to marine mammal populations. Critically endangered species including the vaquita and baiji have largely been extirpated by fisheries interactions that may ultimately result in their extinction.

Derelict and active fisheries netting, commercial monofilament lines, crab-trap lines and rope impact cetaceans directly through entanglement or entrapment. External evidence of net entanglement may include gear impressions along the surface of the skin or oral mucosa hatched or linear furrows , abrasions, incisions, lacerations, and subcutaneous hemorrhage Fig.

However, surface evidence of entanglement may not always be apparent, particularly when animals are entrapped in a trawl with large numbers of fish that prevent direct contact with the netting.

In these instances, animals may present in good nutritional condition with stable white tracheobronchial froth, hyperinflated lungs with generalized pulmonary edema, congestion and subpleural emphysema. Pleural and pulmonary petechiae and ecchymoses may also be noted. Diagnosis may be contingent on the circumstances of death. In those animals that are entrapped at depth, gas bubble formation and embolization may occur with rapid accent and the pulmonary and renal microvasculature should be closely evaluated for possible fat emboli Moore et al.

Fishing line laceration and wounds in the tail stock of a bottlenose dolphin. Items like fishing line and nets can lacerate tissue and create deep wounds. With nets or longline and crab trap lines that are tethered to the substrates, once entangled small cetaceans may be trapped under water, die from asphyxiation, and present with gross lesions consistent with entanglement. With large and smaller cetaceans that are released or may breach the line or netting, subsequent wrapping or entanglement of the gear may occur.

There is a predilection for rope and net entanglement of the peduncle or tail stock, fins, flippers and oral cavity. Depending on the degree of constriction or compression and anatomic location, vascular perfusion may be impaired with hypoxia and ischemic necrosis of distal extremities.

In severe cases, amputation of an appendage may occur either acutely with incision on impact or more chronic ischemia. With more protracted entanglements, animals typically lose condition and may have varying degrees of granulation tissue, fibrosis with osseous metaplasia, periosteal bone proliferation, and embedded fishing gear. If hemorrhage is apparent, a time line may be delineated by differential observation of erythrocytes, hematoidin or hemosiderosis, and margins of bone fractures should be closely evaluated to assess the extent of necrosis, inflammation, and callous formation.

Exertional myopathy and myoglobinuria may also be apparent, and with more chronic cases, adrenocortical hyperplasia with lipoidal degeneration may be evident. Once gear is released, wound resolution may occur with primary and secondary intention healing.

At necropsy, it is important to photo-document and diagrams the course of the fishing line or rope throughout the carcass wrapping pattern and note any knots that may be present. In animals with chronic entanglement with advanced autolysis with generalized skin sloughing, the raised linear ridges of fibrosis associated with entanglement are noted and may feature superficial plaques or plugs of adhered epidermis due to adhesions.

Based on long-term data analysis, it is suggested that persistent organic pollutants and harmful algal blooms toxins may be associated with an increased risk of entanglement. If feasible, samples to screen for these compounds should be harvested at necropsy.

In some instances, the force of initial impact may be so severe, that fracture of the rostrum or mandible with tooth loss may be evident.

An indirect consequence of fisheries interaction is depredation, a learned behavior recognized predominantly in killer whales, false killer whale, pilot whales, and sperm whales characterized by removal of fish from long line hooks. In rare instances, hooks have been ingested and penetrated the oropharynx, resulting in secondary septicemia. This behavior may also result in whale harassment and possibly gunshot, further contributing to the loss of these animals.

Andreia Dilge Pundit. How do dolphins sleep? When sleeping , dolphins often rest motionless at the surface of the water, breathing regularly or they may swim very slowly and steadily, close to the surface.

In shallow water, dolphins sometimes sleep on the seabed rising regularly to the surface to breath. Wangjun Fadin Pundit. Are dolphins in the whale family? Whales Cetacean are divided into two group's baleen whales Mysticeti toothed whales Odontoceti. Dolphins are toothed whales and the largest dolphin is the Orca generally mistaken for a whale due to its name killer whale.

A related family to dolphins are Porpoises. Vicent De Hera Teacher. Which is the largest animal in the world? The Blue Whale. Shaneka Urigoiti Teacher. What oceans do dolphins live? Specifically one of the best-known species, the bottlenose dolphin lives in every ocean of the world except the Arctic and the Antarctic oceans. The Atlantic spotted dolphin, lives all over the tropical and temperate areas of the Atlantic Ocean avoiding the Artic and Antartic regions. Duha Dubus Teacher. Are cetaceans social creatures?

Social Behavior. Social behavior in cetaceans runs the gamut from species that are largely solitary to those that are highly social. Baleen whales are rarely seen in groups of more Two Atlantic bottlenose dolphins. The most highly social species are found among the toothed whales. Ciro Rovinsky Teacher. Do whales have teeth? Whales With Teeth.

Francheska Tiedgens Reviewer. Is a beluga whale a dolphin? I just did my research, and the answer is: the beluga is neither a dolphin , nor a porpoise, nor a whale.

Belugas are more closely related to narwhals, for they are both part of the family Monodontidae, meaning a subfamily of cetaceans that include unusual looking whales , like the beluga and the narwhal.

Cian Lennartz Reviewer. Are cetaceans carnivores? In fact all species of whale, dolphin and porpoise are considered carnivores. Among the 80 or so estimated cetaceans cetaceans include all species of whale, dolphin and porpoise all species are broken down into two groups or suborders which are known as the toothed whale and baleen whale suborders.