The posts this week are brief overviews of EACH of the
otter species, focusing on recent information about each species and a
vid or 2...
This otter is second only to the sea otter in it's use of marine environments, only occasionally traveling up freshwater rivers in search of food.
Marine
Otters seem to be the only otter other than the sea otter that do not
require access to fresh water to wash themselves. Though Marine Otters
tend to be solitary, they are generally friendly (but not highly
sociable) with other otters. They do sometimes hunt cooperatively,
groups of two or three otters working together to catch larger fish.
Also, Marine Otters have hairy noses! (Also known as the Sea Cat)
Status: Endangered and Decreasing
Marine Otters (distribution shown in yellow on the map to the left) live along the west coast of South America, from Peru to Chile, with a few noted "around the corner" in Argentina.
They tend to live in diversity rich areas along rocky shores with caves.
The habitat range of the Marine Otter overlaps in Chile with the other "most southerly" Lontra-otter, the South American River otter.
Videos of these agile little otters in the water are amazing to watch!
and on a rocky shore...
If you want more in-depth reading a few research articles you could explore on these otters includes:
> Non-invasive genetic analysis reveals high levels of mtDNA variability in the endangered South-American marine otter (Lontra felina), Juan Valqui (Email), Günther B. Hartl, Frank E. Zachos, 2010
This week we'll be looking at... wait for it... OTTERS!
Which otters?!?
ALL OTTERS!
We'll take a
brief peek each day at what is currently going on with each of the otter species
around the world, right now...
First, some basic info about each species. There are 13 known modern species of otters, spread out across 5 of
the 7 continents of the world. Otters are not found in Australia, the
surrounding islands, or Antarctica. See map above for distribution of
specific species.
Currently all, but one, of the species are experiencing a decline in
populations. Five otter species are considered endangered, 2 are considered vulnerable
(or near threatened), 5 are listed as near threatened, and only one of the species listed is in the
category of "least concern" by the IUCN Otter Specialist Group.
Otter species status:
Status
Population Trend
Sea Otter ~ Enhydra lutris
Endangered
Decreasing
North American River Otter ~ Lontra
canadensis
Least Concern
Stable
Neotropical Otter ~ Lontra
longicaudis
Near Threatened
Decreasing
Marine Otter ~ Lontra felina
Endangered
Decreasing
South American River Otter ~ Lontra
provocax
Endangered
Decreasing
Giant Otter ~ Pteronura
brasiliensis
Endangered
Decreasing
Spotted-Necked Otter ~ Hydrictis
maculicollis
Near Threatened
Decreasing
African/Cape Clawless Otter ~ Aonyx
capensis
Near Threatened
Decreasing
Congo Clawless Otter ~ Aonyx
congicus
Near Threatened
Decreasing
Eurasian Otter ~ Lutra lutra
Near Threatened
Decreasing
Hairy Nosed Otter ~ Lutra
sumatrana
Endangered
Decreasing
Smooth Coated Otter ~ Lutrogale
perspicillata
Vulnerable
Decreasing
Asian Small-Clawed Otter ~ Aonyx
cinereus
Vulnerable
Decreasing
An introduction to each otter species...
Sea Otter ~ Enhydra lutris
Sea
Otters spend their entire lives in the ocean, only leaving the water in
the case of extremely bad storms. They are also one of the known
tool-using mammals, using rocks to break shells open so they can consume
the shellfish inside. It is important that they are able to do this
well because they have to eat about 30% of their body weight every day!
North American River Otter ~ Lontra
canadensis
North American River
Otters are highly adaptable to different types of habitats, but are very
sensitive to pollution and changes in water quality. They are extremely
playful, and turn almost all regular activities into a game. They do
not tend to pair-bond (though sometimes they do), but males will help to
raise the pups if given the opportunity. Males tend to be more solitary
than females, but they don't do well alone for long periods of time and
will seek out the company of other otters.
Neotropical Otter ~ Lontra
longicaudis
Unlike most otter
species, Neotropical Otters are relatively solitary. Male and female
Neotropical Otters meet one day a year for breeding, and then go their
separate ways. Neotropical Otters prefer clear, fast-flowing water.
Habitat destruction and water pollution are major threats to this
species.
Marine Otter ~ Lontra felina
Marine
Otters seem to be the only otter other than the sea otter that do not
require access to fresh water to wash themselves. Though Marine Otters
tend to be solitary, they are generally friendly (but not highly
sociable) with other otters. They do sometimes hunt cooperatively,
groups of two or three otters working together to catch larger fish.
Also, Marine Otters have hairy noses! (Also known as the Sea Cat)
Southern River Otter ~ Lontra
provocax
Southern River Otters tend
to have a very short life span. Few live to maturity, and only 1% live
to 10 years of age. They are generally solitary, coming together mainly
to mate. The female raises the pups alone, and there are no social
groups beyond this. They have territories like other otters, but the
size of these territories is unknown and it appears that they are not
particularly defensive of them.
Giant Otter ~ Pteronura
brasiliensis
From nose to tail,
Giant Otters can be up to 6ft long! Their tails are flattened and
flanged, and very strong. Their ears are comparably small, and their
eyes very large. Giant Otters are at the top of the Brazilian food
chain. They eat fish, small caiman, crustaceans, snakes, and birds.
Giant Otters are incredibly sociable, and often hunt in groups. They
live in family groups of ten or more, sometimes up to twenty otters!
Spotted-Necked Otter ~ Hydrictis
maculicollis
Due to genetics work done on otters, this otter has been put in to a new genus, Hydrictis! (more about that in an other post!)
Spotted-necked Otters
are fairly small, weighing form 10 to 20 lbs.They live alone or in small
family groups, but often form social and hunting groups of five to
twenty members. They spend more time in the water than other freshwater
species, almost never leaving the water's edge. Resting sites, holts,
latrines, and breeding areas are all right next to the water; they are
not very agile on land. Like other otters, the Spotted-necked Otter
tends to turn everything it does into a game.
Cape/African Clawless Otter ~ Aonyx
capensis
The Cape Clawless Otter's
feet have almost no webbing, and claws only on the three middle toes of
the hind feet. The front feet are very sensitive and hand-like. In fact,
they are so dexterous with their front paws that they are left- or
right-handed, just like people are. They use their hands to dig for prey
in the mud or under rocks. They tend to form loose social and foraging
groups with other otters. Like other otters, they are incredibly
playful and are excellent swimmers.They don't spend as much time in the
water as other otters, and are willing to travel farther from it in
search of a new home. (Also known as African Clawless Otter)
Congo Clawless Otter ~ Aonyx
congicus
Congo Clawless Otters'
back feet have small claws on the three middle toes, and very little
webbing. The front feet have very small claws and no webbing. The front
paws are very sensitive, like those of its close relative the Cape
Clawless Otter, to increase success in finding food under rocks and in
the mud. Their short fur (providing less insulation) and the
abbreviated webbing of its feet make the Congo Clawless Otter the least
adapted otter for life in the water. Congo Clawless Otters are mostly
solitary, only interacting with other otters when monogamous pairs come
together to mate.
Eurasian Otter ~ Lutra lutra
Eurasian
Otters are found almost everywhere in Europe and Asia that is near
water, fresh or salt, as long as there are freshwater pools nearby for
drinking and bathing. They tend to live alone except when mating, when
the male and female may stay close together for about a week, or for
females, when raising a litter. Though they are excellent swimmers,
Eurasian Otters can only hold their breath for about 30 seconds!
Hairy Nosed Otter ~ Lutra
sumatrana
Very little is known
about the Hairy Nosed Otter. It is endangered and incredibly rare. The
nose is completely covered in hair, and the feet are webbed, with strong
claws.The major threat to Hairy Nosed Otters is from humans: hunting,
habitat competition, destruction, and pollution. Despite efforts to
establish a captive breeding program, there have only been three of
these otters held in captivity (and unfortunately, all male).
Smooth Coated Otter ~ Lutrogale
perspicillata
The Smooth Coated
Otter prefers to live in undisturbed areas. They hunt during the day and
at night, sometimes alone and sometimes in large groups. Smooth Coated
Otters mate for life, and live in family groups consisting of the mated
pair and their pups (often including full-grown pups). The alpha female
is dominant and determines hierarchy within the group, while the alpha
male moves the group through their territory. Smooth Coated Otters are
proficient both on land and in water. They are powerful swimmers, and on
land they climb and jump quite well.
Asian Small-Clawed Otter ~ Aonyx
cinereus
The Asian
Small-Clawed Otter is the smallest of all otter species, and also the
most social. They mate for life, and live in family groups of between
four and twelve, and sometimes up to twenty, otters. The group hunts,
plays, and sleeps together. These otters will travel a long distance out
of water in search of new habitats. They don't generally dive deeper
than their body length in search of food, and spend more time out of the
water than most otter species.
(Also known as Oriental Small-Clawed Otter)
Earth Day is dedicated to deepening understanding of the
earth, and the creatures that live on it. By understanding the various ways
life has adapted to different conditions, we gain an appreciation for life in
all its forms and increase our resolve to preserve habitats for all forms of
life. One unique adaption has allowed mammals, most commonly land residents, to
live in the sea.
Orcas (killer whales) are in the dolphin family, Delphinidae.
Dolphins are marine mammals and as such are perfectly
adapted, both anatomically and physiologically, to life in the sea. Before we
go any further, let’s make sure we understand each other by defining a few
terms. A marine organism is one that lives in the sea. According to New Webster’s Medical Dictionary,
anatomy is “the structure or study of the body”, and physiology is “the science
of dealing with the normal functions of living organisms or their organs”. To
put it more simply, anatomy and physiology collectively mean how a creature is
“put together” and how it “works”.
Since dolphins and whales are mammals, they must breathe
air. Since they live in the sea, they must swim and dive. Most of the dolphin’s
adaptations to the marine environment are related to allowing them to swim and
dive for extended periods, yet
^ typical dolphin anatomy, click for larger image
breathe using lungs like those of humans instead
of using gills like those of fish.
The marine environment is much different than that of the
land, so to understand how dolphins have adapted to sea life we must first
understand some of the unique problems that they face. One of the major
problems involves the relationship between gas exchange and pressure. As one
descends into the ocean depths, the pressure exerted on the body by the
surrounding water increases. This increased pressure on the lungs causes the
gases in the lungs, namely oxygen and nitrogen, to leave the lungs and enter
the bloodstream. If much time is spent at depth, a large amount of nitrogen may
be dissolved into the blood. Upon resurfacing, the pressure decreases and the
dissolved nitrogen may expand enough to form bubbles in the blood and other
tissues. This is similar to the formation of carbon dioxide bubbles inside of a
bottle of soda pop when the cap is removed, and the pressure inside the bottle
is suddenly decreased. The accumulation of such nitrogen bubbles in the joints
causes a painful disease known as “the bends” in humans. Since dolphins dive
frequently and for extended periods, why don’t they get the bends? Let’s
consider another problem that diving mammals have and since the adaptions for
bother are inter-related, we will find how nature has provided for the dolphin.
When humans take a breath-hold dive, they can stay
underwater for 3 to 5 minutes, depending mainly on how much oxygen they have in
their lungs. The lungs of a dolphin, relative to its body size, are no larger
than our own. How then can a dolphin remain submerged for such long periods?
Among the numerous adaptations of the dolphin for life in
the sea, the most important ones for oxygen conservation are: 1) lung collapse,
2) circulatory redistribution, 3) modified oxygen – storage mechanism, and 4)
resistance of the tissues to lactic acid build-up.
The lungs of the dolphin are made to collapse under
pressure. Some of the ribs are even jointed to assist in this collapse. When
the pressure is great enough, the lungs collapse to the point where exchange
ceases. With no gas exchange, excess nitrogen cannot enter the bloodstream and
the bends cannot occur.
To reduce the use of oxygen during a dive, the circulatory
system has become adapted to supply oxygen only to tissues that need it most,
namely the heart and the brain. When a dolphin dives, the heart slows way down
and blood flow is restricted to the heart and the brain. The muscles and other
organs receive only a little blood.
The method by which oxygen is stored is quite different with
the dolphins, too. “Hemoglobin”, a pigment in our blood,
carries oxygen from our lungs to the tissues, with a small amount being
stored
in "myoglobin”, another pigment in our muscles. Dolphins, however, have more
hemoglobin than we do and much more myoglobin, so the muscles can get plenty of oxygen during periods of reduced
blood flow.
When muscles operate with oxygen for a while, they build up
a waste product called “lactic acid”. Everyone knows that burning sensation you
get in your muscles from working out too hard. This is caused by working the
muscle so hard that the stored oxygen is depleted and lactic acid accumulates.
Due to the circulatory redistribution described above, the muscles must operate
for prolonged periods with little blood circulation. Their muscles have evolved
with a biochemical resistance to such side effects as burning and cramping due
to over-accumulation of lactic acid.
Respiratory specializations such as those listed
above have enabled the dolphin, and air-breather, to spend very little time at
the surface breathing, and spend the greater majority of its time swimming in
the ocean’s dept
