Females will typically be won by males through battles over territory, however, males have also been seen to court young females by dancing for them in the water. They dance by doing flips, and spinning through the water and flashing their mane up and down above the water surface. There is also a behavior that males do that researchers have called the “wet noodle”. It involves the males sticking half of their body out of the water and shaking the upper half of their body back and forth making them look like a flailing noodle. Some males with very bright manes may be pretty enough to catch the attention of a female in the river system. If he can impress her with a brief dance in the water showing off his vibrant mane she may follow him back to his den. If the males den is high quality, then the female will stay with the male and he may be able to start his very own pride.
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Males have an intricate way of fighting one another. First, the males will assess each other’s fitness. The male with the biggest brightest mane and largest canines may be able to intimidate the other male and may not have to fight at all. However, when intimidation doesn’t work males use their large powerful forelimbs, and long canines to inflict devastating blows to their opponents.
The stellar river otter is an incredibly territorial and aggressive animal. The males will monitor their territory daily while foraging for frogs, and fights between neighboring, and young males happen frequently. When a young male is able to defeat a dominant male who is in charge of a pride he is able to take over the male’s pride. Many young males go around challenging other males but due to their lack of experience and size, they are very easily beaten. The male stellar river otter maybe six to eight years old before he is able to finally get a female of his own, but then he must spend the rest of his days defending his territory from rival males. The stellar river otter may live to be 20 years old and will spend its time defending its territory to the very end.
P. hydrobothynus lives in large social groups of three to twelve members. A group of otters is called a pride when they are on land, and a raft when they are in the water. There are never more than two males per pride of stellar river otters, and these males are always related. A male may have a number of females ranging from one to six. In a pride of otters, there is a dominant male who rules over the entire pride. If the second male is lucky he may have the opportunity to have a female of his own however this usually is not the case. Female stellar river otters may have one to three pups a year. The male will only have one pregnant female at a time and the entire group works together to raise the pups. This prevents overcrowding in the burrows and it gives the pups more attention and resources due to a group effort to raise them. Pups stay with the pride until they are two years old. Young males are kicked out of the pride by their father, and young females will either leave on their own or be taken by another prides male.
The kidneys of the stellar river otter look very similar to the American river otter Lutra Canadensis. This is a multi-lobed kidney which is commonly found in many marine and aquatic mammals. The kidneys are multi-lobed and are fully equipped to remove toxins however they are not specialized for water conservation. Because the stellar river otter lives in a freshwater environment it does not need kidneys adapted for the conservation of water. Water is extremely prevalent in the habitat of the river otter and it has little need to conserve it when there is a river just outside its back door. The river otter also has a large multi-lobed liver, which supports the idea that its body is more adapted to purify toxins than it is to conserve water.
When looking at the male stellar river otter it possesses the morphology of a powerful predator. The two long pairs of canines and huge forelimbs make this mammal an intimidating predator. The mane of the stellar river otter can be erected and lowered to accommodate for the situation. When swimming the mane is lowered to make their body more streamline. However, there is evidence suggesting that the mane may be used when P. hydrobyothynus is turning and uses the mane like a sail. When walking around on land P. hydrobothynus keeps its mane erect at all times. P. hydrobothynus is able to erect and lower its mane by contracting and relaxing its arrectorus pilorum muscles. The arrectorus pilorum is the muscle responsible for causing goose bumps in humans. One of the other most distinguishing factors that the male’s skeleton has is its large olecranon process, while this does aid in swimming it is also very common in mammals that specialize in fossorial locomotion.
P. hydrobothynus is a sexually dimorphic species of otter. The male otters have very large and colorful mane made of orange, yellow, and red and a dark brown body with a white underside. They have a short stocky body, a short fat tail, and a much more robust pectoral girdle. Males are usually only 1 meter long, and 0.35 meters tall. The female otters are dark brown in color with a white underside and are camouflaged in the murky water and muddy banks. The female stellar river otters are built like a traditional river otter and are very streamline with a long wing-like tail, and a longer skinnier body. Females tend to be roughly 1.2 meters long, and are 0.2 m tall. The male and female both have very thick fur to stay dry and for insulation. The two sexes are so morphologically different they were first thought to be different species; however, a distinct red diamond pattern on the chest of this species was the first clue that the discoverers had in determining they were the same species.
The Tasmanian Devil is an iconic, and charismatic species that lives on the Island of Tasmania off the coast of Australia. Reports started 1996 of Tasmanian Devils with large facial and neck tumors. The cancer is transmitted through an infected individual by biting a healthy individual. Due to the Tasmanian Devil’s tendency to fight, and bite each other over territory, food and sex the tumors are passed fairly quickly through populations. The tumors begin to proliferate and can prevent the Tasmanian Devil from breathing, and eating; however, it may take time for the tumors to get large enough to do kill the infected individual giving the cancer plenty of time to get passed on. The tumors are killing many Tasmanian Devils and certain populations throughout Tasmania have been reduced more than 90% in the last 20 years and is now considered endangered.
Devil face tumor disease or DFTD is exterminating populations of Tasmanian devils throughout Tasmania due to its ability to be transmitted between individuals. The cancer is able to do this not through the use of a virus but instead, the cancer cell itself is able to bypass the devil’s immune system and colonize the host's tissue. This study looked into the mechanics of how this happens and how it can be treated. The cancer cells go undetected by the host's immune system due to the low genetic diversity of the MHC gene and overall poor genetic diversity, and inbreeding of the populations of Tasmanian devils throughout the island. MHC gene helps the body create T-cells and immune responses to tumors. The cancer cells express this gene allowing it to evade the host's immune system because it recognizes it as its own cell due to the poor genetic diversity of this gene. Methods to help stop this have been attempting to develop a vaccine, keeping healthy populations of Tasmanian devils in captivity, and introducing new Tasmanian devils into areas with very low genetic diversity in hope of creating resistant individuals.
The fact that a type of cancer can be transmissible is very scary and somewhat intimidating. Many populations of Tasmanian Devils don’t stand a chance against this cancer and their future is looking very bleak. The one bright side to this disease is that we can study transmissible cancer. These cancers are extremely rare with only a few other cases in the entire world. Understanding how these cancers work will help us develop new methods of treatment in case more diseases like this develop in the future. Transmissible cancers are extremely dangerous and have shown that they can obliterate a species in no time at all. I believe that studying this cancer and finding a cure for it is going to be incredibly beneficial for humans and the Tasmanian devils.