A Missive on Sea Otters

[Hanrahan 2983]

C H A R L E S   N A P I E R , 

 

D O C T O R    O F M E D I C I N E 

 

O N   T H E   S U B J E C T   O F

 

M U S T E L A   L U T R I S 

O R

T H E   S E A O T T E R

A N D   I T S

L I V I N G

H A B I T S

 

 

P R I N T E D    I N L L R Y I A 

 

B Y

 

T H E   F R O N D   S O C I E T Y

   A C A D E M I C   P R E S S 

 

I N 

 

A N N O   D O M I N I   MDCCXXIX

    I N T R O D U C T I O N,

 

    Mustela Lutris, or the ‘Sea Otter’, is a species of marine Mammal that inhabits coastlines of northern, and temperate continents and islands. Typically weighing between thirty, and one-hundred pounds. They are a subset of the ‘Mustela’, a group which many weasel type animals share. Differing from the majority of Marine Mammals, the Otter does not use blubber as insulation against the cold of the waters, but thick layers of fur, and grease which protects it. As well, the Otter is far better suited to life on land than any other aquatic mammal, having both hands and feet, instead of flippers. Inhabiting Coastal regions, Otters swim to the shore floor to prey upon a variety of bottom-feeding animals, such as clams, urchins, and crabs. The Animal remains a remarkable species in twofold ways; it has been documented that the Otter uses tools - stones, by which to break open the shells of prey it has found, and secondarily, the extraordinary necessity for their place in the ecosystem. As they feast upon Urchins, they control the local population of kelp-grazers. Without the Otters, the urchins would swarm over the kelp forests, and turn it into a barren wasteland.

 

Charles Napier, Dr, A.D MDCCXV.

 

A perched Sea Otter.

 

 

The Sea Otter, (Mustela Lutris), is a Marine Mammal. It is related to species of the ‘Mustela’ Family, which includes Ferrets, Badgers, Martins, and Minks. Unlike those just listed however, the Otter widely differs from the rest of its kin, being both aquatic, and by far the largest of all the Mustela related animals. So far, there are ten species of Otter identified, with habitats ranging from coastal basins, to inland rivers. The subject of today's paper will be the ‘Sea Otter’, the most common of the Otter family. 

 

To begin, the Otter is small by the standards of Marine Mammals - the smallest of them all, when compared to Whales, Dolphins, and seals. However, they are the largest of their species, weighing an average of seventy pounds, and standing at three and a half feet long. Sizes and weights differ with both age and sex, as Otters exhibit Sexual Dimorphism. Females on average are a third smaller than the males, in both size and weight. Similar to seals, they have a rear pair of flipper-like feet, elongated with webbing. Upon the front, they have more terrestrially shaped paws that are more suited for ground based movement, as well as grabbing their primary food sources. 

 

Unlike all other large marine Mammals, the Otter has no blubber to keep itself insulated in cold waters. Instead, it boasts the thickest fur in the animal kingdom with two layers. Long guard-hairs protect the soft underfur from taking on water, and the underfur keeps the animal incredibly warm. The fur is not shed in an annual molting, but instead it is preened year-round, constantly being tended to and regrown to ensure buoyancy and warmth. Instrumental to it’s grooming is the Otter’s remarkably flexible skeleton, allowing it to bend and reach virtually anywhere on its body. This flexibility also serves as a defensive mechanism, the Otter able to twist and turn out of the way of predators in its environment. Fur colours have little range among adults but in youth, speckles appearing on the belly-fur, then gradually fading as adulthood approaches. All Otters have a light furred face, in stark contrast to their dark bodies. 

 

The Otter’s main method of aquatic motion is an undulating swim in which the rear of the body, including the feet and tail move up and down. It tucks it’s front paws tightly to its chest, and folds its ears back while swimming, capable of reaching significant speeds underwater. When idle at the surface, it floats upon its back and gently paddles its feet side to side for any movement necessities. At complete rest, all four limbs can be folded over the chest to provide insulation in cold weather. In the opposite situation, the feet may be held underwater in hot weather to provide vital cooling. The whole animal is highly buoyant, with both a remarkably large lung capacity providing internal carrying of air, as well as the large amount of air stored within its fur. To this end, young Sea-Otters cannot in fact swim, and will float to the surface of the water if they attempt to dive. Lastly, on land the Otter ambles clumsily, but can do a ferret-like bounding movement if required.

 

Upon its snout are long, sensitive whiskers that assist in the location of food and prey in the typically murky water of its habitat. Their noses seem to be sensitive, and it can be safely assumed that both touch and scent are the primary senses by which the Otter locates prey. A Particular quirk of the dentition of the Otter is that virtually all mature Otters have purple teeth and bones. This is presumably from the colouring of the Urchin upon which they feed - purple. Finally, the Otter is a remarkable freshwater species in that although certainly a mammal, it can drink salt-water with no side-effects. Dissections have revealed disproportionately large kidneys. 

 

An Otter floating in a tidal pool.

 

    The Behavior of the Otter is complex, as they are an intelligent species capable of adaptation to varying environments. Some absolutes however, do remain. The species is a dinural one, meaning that they operate not largely in the day or night, but in the moments of sunrise and sundown. They feed and forage in the morning, then begin a rest period until mid-day. During this period, they either sleep, or groom themselves. At mid-day, they will spend an hour or so foraging, and then engage another rest period until sundown, when their longest and most active foraging period begins. Females with young pups (Sea Otter Juveniles) spend far more time sunset foraging than morning foraging. 

 

    Much of their rest time is spent grooming, untangling knots, cleaning the fur, removing loose fur, rubbing their bodies to squeeze water out of it, and blowing new air into it. Observation has led earlier people to think of Otters as ‘Itching,’ and a dirty species plagued by mites, yet the vast majority of samples have turned up entirely negative for any nit, mite, or parasite. When eating, in fact, Otters roll to ensure the jetsam from their meals does not stick to their fur. 

 

    Otters hunt in a diving fashion, foraging along the bottom of coastal areas, piers, and kelp-forests for a variety of foods. Otters typically dive for two minutes, though a dive of four has been recorded. It is the only Aquatic Mammal capable of lifting rocks, and using tools in its hunt. They will pick up rocks, and drop them to dislodge mussels, clams, and snails from their various surfaces. When hunting fish, it will grab them with their claws - not their teeth. 

 

    All Otters carry with them a rock particular to the individual, which they use to smash open the closed shell of their prey. Upon a dive, an Otter will collect a number of clams, then surface and float upon its back. It will then either simply rip open the clam, or, if the clam is providing a challenge, place it upon its belly and lift the rock, bringing it down upon the invertebrate and breaking the shell. 

An Otter and Crab.

 

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    The social structure of Otters is complex and varied, depending on age, location, and ecological pressures. However, there are many base observations that apply to all. Otters forage and hunt alone, but they conglomerate in large groups called rafts. Rafts are sequestered by gender, as males have one group, and the female and pups have another. Most rafts are around twenty, to a hundred animals, but verbal stories have reported rafts as large as one-thousand animals. When at rest, Mother Otters may wrap and tether their young in kelp to hold them in place whilst they go on dives. Mature otters occasionally do this as well, depending on the current and weather. 

 

    In mating, a male otter is most likely to mate if he maintains a territory that is satisfactory to females. Autumn is the breeding season for Otters, and thusly defend their territory ranging from late spring to mid-autumn. Defense mostly consists of patrolling, and physical confrontation is extremely rare. Females however will move from one territory to another freely, and in fact outnumber the males around five to one.  

 

Otters exhibit dimorphic vocal sounds, the females cooing, whereas the males grunt. When in distress, both may hiss, whistle, and yip. They are a playful animal, spending some idle time wrestling, swimming, and playing. 

 

Two Otters rafting.

 

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[Vermy 1484]

Horren ‘Rosebush’ Bogbelly abundantly smiled ”Aneat’or book on Arcan sea life... T’is man is a genius!”