Trichechus
Trichechus inunguis
Trichechus manatus
Sirenia
Dugong
Diaphragm structure and function in the Florida manatee (Trichechus manatus latirostris). (1/14)
Relative to many other mammals, little is known about the functional morphology of the four extant species of the order Sirenia. In this study, 166 Florida manatee (Trichechus manatus latirostris) carcasses fresh enough to collect detailed anatomical information were examined to describe the gross anatomy of the diaphragm. Our results show that the Florida manatee's diaphragm differs from those of other mammals in that it: lies in a dorsal plane, rather than in the more typical transverse plane; is located dorsal to the heart and does not attach to the sternum; and attaches medially at the "I"-shaped central tendon to bony projections extending ventrally from the vertebral bodies, forming two distinct hemidiaphragms. The manatee's transverse septum is a separate structure that lies at a right angle to the diaphragm and separates the heart from the liver and other viscera. The extreme muscularity of the diaphragm and the ability of manatees to adjust their position in the water column with minimal external movement suggest that diaphragmatic contractions may change the volume of each pleural cavity to affect buoyancy, roll, and pitch. We also hypothesize that such contractions, in concert with contractions of powerful abdominal muscles, may compress gas in the massive large intestine, and thereby also contribute to buoyancy control. (+info)Thyroid hormone concentrations in captive and free-ranging West Indian manatees (Trichechus manatus). (2/14)
Because thyroid hormones play a critical role in the regulation of metabolism, the low metabolic rates reported for manatees suggest that thyroid hormone concentrations in these animals may also be reduced. However, thyroid hormone concentrations have yet to be examined in manatees. The effects of captivity, diet and water salinity on plasma total triiodothyronine (tT(3)), total thyroxine (tT(4)) and free thyroxine (fT(4)) concentrations were assessed in adult West Indian manatees (Trichechus manatus). Free-ranging manatees exhibited significantly greater tT(4) and fT(4) concentrations than captive adults, regardless of diet, indicating that some aspect of a captive existence results in reduced T(4) concentrations. To determine whether this reduction might be related to feeding, captive adults fed on a mixed vegetable diet were switched to a strictly sea grass diet, resulting in decreased food consumption and a decrease in body mass. However, tT(4) and fT(4) concentrations were significantly elevated over initial values for 19 days. This may indicate that during periods of reduced food consumption manatees activate thyroid-hormone-promoted lipolysis to meet water and energetic requirements. Alterations in water salinity for captive animals did not induce significant changes in thyroid hormone concentrations. In spite of lower metabolic rates, thyroid hormone concentrations in captive manatees were comparable with those for other terrestrial and marine mammals, suggesting that the low metabolic rate in manatees is not attributable to reduced circulating thyroid hormone concentrations. (+info)Functional morphology of venous structures associated with the male and female reproductive systems in Florida manatees (Trichechus manatus latirostris). (3/14)
The reproductive organs of Florida manatees (Trichechus manatus latirostris) are surrounded by thermogenic locomotory muscles and insulating fat. Manatees are reported to maintain core body temperatures of 35.6 degrees -36.4 degrees C, temperatures known to interfere with production and maturation of viable sperm in terrestrial mammals. We describe two novel venous plexuses associated with the manatee epididymis. Each epididymis is located in a hypogastric fossa at the caudolateral extremity of the abdominal cavity. Each hypogastric fossa is lined by an inguinal venous plexus that receives cooled blood from a superficial thoracocaudal plexus. We conclude that male manatees may prevent hyperthermic insult to their reproductive tissues by feeding cooled superficial blood to venous plexuses deep within their bodies. Female manatees also possess hypogastric fossae and venous structures similar to those found in male manatees. The ovaries, uterine tubes, and distal tips of the uterine horns are located in the hypogastric fossae. We suggest that the thermovascular structures we describe also prevent hypothermic insult to female manatee reproductive tissues. The venous structures in manatees are functionally similar to structures associated with reproductive thermoregulation in cetaceans and phocid seals. Thus, these thermovascular structures appear to be convergent morphological adaptations that occur in three clades of diving mammals with independent evolutionary histories. (+info)Characterization of an endogenous retrovirus class in elephants and their relatives. (4/14)
BACKGROUND: Endogenous retrovirus-like elements (ERV-Ls, primed with tRNA leucine) are a diverse group of reiterated sequences related to foamy viruses and widely distributed among mammals. As shown in previous investigations, in many primates and rodents this class of elements has remained transpositionally active, as reflected by increased copy number and high sequence diversity within and among taxa. RESULTS: Here we examine whether proviral-like sequences may be suitable molecular probes for investigating the phylogeny of groups known to have high element diversity. As a test we characterized ERV-Ls occurring in a sample of extant members of superorder Uranotheria (Asian and African elephants, manatees, and hyraxes). The ERV-L complement in this group is even more diverse than previously suspected, and there is sequence evidence for active expansion, particularly in elephantids. Many of the elements characterized have protein coding potential suggestive of activity. CONCLUSIONS: In general, the evidence supports the hypothesis that the complement had a single origin within basal Uranotheria. (+info)Brevetoxicosis: red tides and marine mammal mortalities. (5/14)
Potent marine neurotoxins known as brevetoxins are produced by the 'red tide' dinoflagellate Karenia brevis. They kill large numbers of fish and cause illness in humans who ingest toxic filter-feeding shellfish or inhale toxic aerosols. The toxins are also suspected of having been involved in events in which many manatees and dolphins died, but this has usually not been verified owing to limited confirmation of toxin exposure, unexplained intoxication mechanisms and complicating pathologies. Here we show that fish and seagrass can accumulate high concentrations of brevetoxins and that these have acted as toxin vectors during recent deaths of dolphins and manatees, respectively. Our results challenge claims that the deleterious effects of a brevetoxin on fish (ichthyotoxicity) preclude its accumulation in live fish, and they reveal a new vector mechanism for brevetoxin spread through food webs that poses a threat to upper trophic levels. (+info)Corneal avascularity is due to soluble VEGF receptor-1. (6/14)
Corneal avascularity-the absence of blood vessels in the cornea-is required for optical clarity and optimal vision, and has led to the cornea being widely used for validating pro- and anti-angiogenic therapeutic strategies for many disorders. But the molecular underpinnings of the avascular phenotype have until now remained obscure and are all the more remarkable given the presence in the cornea of vascular endothelial growth factor (VEGF)-A, a potent stimulator of angiogenesis, and the proximity of the cornea to vascularized tissues. Here we show that the cornea expresses soluble VEGF receptor-1 (sVEGFR-1; also known as sflt-1) and that suppression of this endogenous VEGF-A trap by neutralizing antibodies, RNA interference or Cre-lox-mediated gene disruption abolishes corneal avascularity in mice. The spontaneously vascularized corneas of corn1 and Pax6+/- mice and Pax6+/- patients with aniridia are deficient in sflt-1, and recombinant sflt-1 administration restores corneal avascularity in corn1 and Pax6+/- mice. Manatees, the only known creatures uniformly to have vascularized corneas, do not express sflt-1, whereas the avascular corneas of dugongs, also members of the order Sirenia, elephants, the closest extant terrestrial phylogenetic relatives of manatees, and other marine mammals (dolphins and whales) contain sflt-1, indicating that it has a crucial, evolutionarily conserved role. The recognition that sflt-1 is essential for preserving the avascular ambit of the cornea can rationally guide its use as a platform for angiogenic modulators, supports its use in treating neovascular diseases, and might provide insight into the immunological privilege of the cornea. (+info)Marine mammal neoplasia: a review. (7/14)
A review of the published literature indicates that marine mammal neoplasia includes the types and distributions of tumors seen in domestic species. A routine collection of samples from marine mammal species is hampered, and, hence, the literature is principally composed of reports from early whaling expeditions, captive zoo mammals, and epizootics that affect larger numbers of animals from a specific geographic location. The latter instances are most important, because many of these long-lived, free-ranging marine mammals may act as environmental sentinels for the health of the oceans. Examination of large numbers of mortalities reveals incidental proliferative and neoplastic conditions and, less commonly, identifies specific malignant cancers that can alter population dynamics. The best example of these is the presumptive herpesvirus-associated metastatic genital carcinomas found in California sea lions. Studies of tissues from St. Lawrence estuary beluga whales have demonstrated a high incidence of neoplasia and produced evidence that environmental contamination with high levels of polychlorinated biphenols and dichlorophenyl trichloroethane might be the cause. In addition, viruses are suspected to be the cause of gastric papillomas in belugas and cutaneous papillomas in Florida manatees and harbor porpoises. While experimental laboratory procedures can further elucidate mechanisms of neoplasia, continued pathologic examination of marine mammals will also be necessary to follow trends in wild populations. (+info)Latitudinal gradients in greenhouse seawater delta(18) O: evidence from Eocene sirenian tooth enamel. (8/14)
(+info)"Trichechus" is the genus name for three species of aquatic mammals commonly known as manatees or sea cows. These herbivorous animals are found in the waters of the Atlantic Ocean, Gulf of Mexico, and parts of the Caribbean. They are known for their slow movement, wrinkled skin, and paddle-like flippers.
'Trichechus inunguis' is not a recognized medical term or a condition related to human health. It refers to the Amazonian manatee, also known as the southern manatee, which is a large, aquatic, herbivorous mammal native to the Amazon Basin in South America.
The Amazonian manatee (Trichechus inunguis) is one of the three extant species of manatees, along with the West Indian manatee (Trichechus manatus) and the West African manatee (Trichechus senegalensis). These aquatic mammals are known for their streamlined bodies, paddle-like tails, and gentle demeanor.
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'Trichechus manatus' is the scientific name for the West Indian Manatee, also known as the American Manatee. It is a large, aquatic, herbivorous mammal that lives in warm, shallow waters of the Caribbean Sea, Gulf of Mexico, and Atlantic Ocean along the North American coast. They are known for their slow movement, wrinkled skin, and paddle-like flippers. West Indian Manatees are an endangered species due to habitat loss, boat strikes, and other human activities.
"Sirenia" is not a medical term, but a biological classification for a group of aquatic mammals commonly known as sea cows. This order includes four extant species: the Dugong (Dugong dugon), and three manatee species - the Amazonian Manatee (Trichechus inunguis), the West Indian Manatee (Trichechus manatus), and the African Manatee (Trichechus senegalensis). These herbivorous animals are known for their streamlined bodies, paddle-like limbs, and whiskered snouts. They inhabit warm coastal and riverine habitats in various parts of the world.
A dugong is a large marine mammal that belongs to the family Dugongidae. Its scientific name is Dugong dugon. It is also known as the sea cow because of its habit of feeding on seagrasses. Dugongs are found in warm coastal waters of the Indian and Pacific Oceans, ranging from East Africa to Vanuatu in the west and from Japan to Australia in the east. They can grow up to 3 meters in length and weigh between 200-500 kilograms.
Dugongs have a streamlined body with a flat, paddle-like tail and two flippers. Their skin is thick and wrinkled, and they are usually gray or brownish-gray in color. Dugongs have a unique feeding apparatus that allows them to graze on seagrasses, which include specialized lips and teeth.
Dugongs are social animals that live in small groups called herds. They communicate with each other using a variety of sounds, including clicks, chirps, and whistles. Dugongs have a long lifespan, with some individuals living up to 70 years or more.
Unfortunately, dugongs are threatened by various human activities, such as hunting, habitat loss, and entanglement in fishing nets. They are currently listed as vulnerable on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.