Endangered Species Series - The Leatherback Sea Turtle

The Species of Origin

Presents:

Leatherback Turtle (Dermochelys coriacea)
Critically Endangered

Leatherback Hatchling

• Average weight: Up to 900 kg (2,000 lbs)
• Average length: Up to 2 m (7 ft)
• Average lifespan: 30 - 45 years
• Range: Worldwide distribution (tropical to sub-polar oceans)
• Nests: Tropical (rarely sub-tropical)
• Diet: Carnivore – soft-bodied animals such as jellyfish and salps

About:

Leatherbacks, with the widest global distribution of all reptile species (and possibly all vertebrates), are the largest turtles on earth, and the last surviving representatives to a family able to trace their evolutionary lineage further than 100 million years in the past.

Of all sea turtles, Leatherbacks travel the longest migration routes to breed and feed, averaging 6,000 km (3,700 miles) each way. At one time these peaceful giants dominated the Arctic and Antarctic in large numbers, but over the past few decades their population has plummeted to the point of grave concern.

Found in temperate and tropical waters of the Mediterranean Sea, to the Atlantic, Pacific, and Indian Oceans, Leatherbacks are able to travel from Canada and Norway to New Zealand and South America due to their ability to generate and maintain body heat in cold waters. Large body size, a thick layer of fat (high oil content), and adjustments in both swimming activity and blood flow (thermoregulatory – counter-current heat exchange system) are adaptations that have allowed these graceful creatures to travel the various global waters.

The Leatherback shell isn’t hard and bony like other sea turtles. These reptilian relics have an inky-blue carapace [approx 4 cm (1.5 inches) thick] which is fairly flexible, making it almost rubbery to the touch. This leathery shell is filled with oil-saturated connective tissue covering loosely interlocking dermal bones, designed with seven thick, hydrodynamic, longitudinal ridges which taper to a rounded point. 

They have no claws or scales on their flippers; the back ones look and act like paddles or large rudders, while the powerful front ones are quite a bit longer than found in other sea turtles. These amazing creatures can dive deeper than all other turtles, to depths of 1,280 meters (4,200 ft), and can remain submerged for up to 85 minutes.

The adults mate at sea, and then the females journey ashore for the night-time nesting rituals involving excavating a hole in the sand, depositing 80 to 100 eggs, then covering the nest before heading back out to sea. This is repeated several times during the nesting season with 8 to 12 day intervals. Sadly, the beach nesting leaves large disturbed areas of sand which allows for easy detection by predators and poachers.

Interestingly, the temperatures found within the nest will determine the sex of the hatchlings. A mix of both male and female can only occur when the temps stay within the approximate range of 29.5 degrees Celsius (85.1 degree Fahrenheit), while hotter will produce females and cooler will generate males. Surviving males will spend the rest of their lives at sea, while the females will return to the same nesting areas after reaching sexual maturity to repeat the cycle with their own offspring.

Trivia: The largest leatherback ever found was an 8.5-ft-long (2.6-m-long) male weighing 2,020 lbs (916 kg) that washed up on the west coast of Wales in 1988.

What is their Status? 

 

Critically Endangered (IUCN RedList)

From: http://www.iucnredlist.org/apps/redlist/details/6494/0

“The main procedure for evaluating the status of sea turtles is through surveys of reproduction activity at nesting beaches. Decline in nesting has been documented to be much greater than 80% in most of the populations of the Pacific, which has been considered the species' major stronghold. In other areas of its range, the observed declines are not as severe, with some populations showing trends towards increasing or stable nesting activity. Analysis of published estimates of global population sizes (Pritchard 1982, Spotila et al. 1996), suggest a reduction of over 70% for the global population of adult females in less than one generation. The populations in the Pacific Ocean, the species’ stronghold until recently, have declined drastically in the last decade, with current annual nesting female mortalities estimated at around 30% (Sarti et. al. 1996, Spotila et al. 2000). In some areas, formerly abundant rookeries have almost disappeared. For the Atlantic Ocean, the available information demonstrates that the largest population is in the French Guyana but the trends there are unclear. Some of the Caribbean nesting populations appear to be increasing but their sizes are very small when compared to those that nested in the Pacific coasts less than 10 years ago.” (Published in 2000)

Main Threats:

Egg harvesting and illegal poaching have removed more than 95% of the clutches in some parts of the world, particularly Malaysia, taken from nests to be consumed for food or as an aphrodisiac. It’s estimated that only one in a thousand hatchlings survives to adulthood. Long-line and driftnet fishing are also serious threats, causing both adults and juvenile to be captured while on migratory routes. The killing of nesting females on beaches for oil extraction along with traditional hunts and customs are also of serious concern. Finally, oceanic pollutants, especially plastics which resemble jellyfish, their favourite food, are a significant cause of mortality, finding as much as 5 kilograms (11 lbs) of plastic in some individual turtles.

Important Pages & Info:

Free the Leatherback: http://www.freetheleatherback.com/

Vancouver Aquarium – Aqua-facts: http://www.vanaqua.org/learn/aquafacts/reptiles/leatherback-turtles

WWF Global: http://wwf.panda.org/what_we_do/endangered_species/marine_turtles/leatherback_turtle/

Arkive Images: http://www.arkive.org/leatherback-turtle/dermochelys-coriacea/#src=portletV3api

Note 2: This little guy is featured in one of the artworks which I'm presently working on (from The Endangered Species Series). Stay tuned for more info (and the big unveilings), but in the meantime, please have a read and ...

~ Be The Change ~

Endangered Species Series - The Sea Otter

"The Species of Origin" matures and begins to come into its own

Sea Otter (Enhydra lutris)

Sea Otter photo by Tsuneo Nakamura

• Average weight: - Male: 32 to 41 kg - Female: 18 to 27 kg
• Average height: 1.4 m
• Average lifespan: 15 to 20 years  
• Fur: 1.6 to 2.6 million hairs per square cm (thickest of any animal in the world)
• Gestation: 6 to 8 months
• Litter Size: 1 pup, but sometimes giving birth to twins

• Threats: Oil spills, habitat loss and degradation, food limitation, disease, fishing gear entrapment and conflict with shellfish fisheries. 

About:

Although they may look clumsy on land due to mismatched leg sizes, it’s for good reason. The strong hind legs endowed with webbed feed allow amazing manoeuvrability while paddling at great speeds, while the small front legs boasting stiff toes assist with complex food handling. They are the second smallest marine mammals but the largest of the weasel family.

Rather than blubber it’s very thick fur that keeps these marine mammals warm in the icy Pacific Ocean waters. Two layers provide insulation by trapping air between a thick under-fur and a “guard hair” fur layer, which changes colour with age, often from black, pale brown, to silver. 

These hungry little guys are capable of eating ¼ of their body weight a day. They’re preferred snacks are abalones, clams, crabs, mussels, octopus, and sea urchins. After diving over 100 murky metres or slamming shellfish against small rocks in order to get to their food source, otters will then roll and float on their backs to have their meal, their chests becoming the diner table.

Since dirty, matted fur doesn’t work as efficiently to trap sufficient heat the sea otter spends a large of the day cleaning itself. Oil spills are a huge threat to the Sea Otter, making it impossible for the otter to clean away the sticky substance before it freezes to death.

Sea Otter Year-round Range according to Canadian Geographic

Although there used to be hundreds of thousands of Sea Otters living on the Pacific coast between Mexico and Alaska, in the 1700s the fur trade started picking away at their numbers dramatically, causing them to plummet down around 1000 to 2000 in the early 1900s, to the point where they had to be re-introduced to British Columbia (89 of them between 1969 and 1972). Vancouver Island & Goose Island now has an estimated 2500 Sea Otters living off their coasts. Off the coast of California, the numbers have been estimated to be around 2,700 as of 2010, while Canada, Alaska, and Washington combined have seen numbers between 64,600 to 77,300, Russia estimates around 15,000, and Japan only about a dozen according to Defenders of Wildlife.

What is their status? 

Endangered

From: http://www.env.gov.bc.ca/wld/documents/otter.pdf 

"Following reintroduction the Sea Otter population in Canada has increased to about 900 animals and has been growing at a rate of 17 to 20 percent per year. The Sea Otter has been assigned Endangered status by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and receives legal protection as a marine mammal under the Canada Fisheries Act. It has been placed on British Columbia’s Red List and has been legally designated as an Endangered Species under the Wildlife Act. Throughout their range in the U.S., Sea Otters receive protection under the Marine Mammals Protection Act. The California population, a separate subspecies (variety) named the “Southern Sea Otter,” is afforded additional Federal protection as a Threatened Species under the U.S. Endangered Species Act."

A few Important Sea Otter Pages - Info:

Defenders of Wildlife: www.saveseaotters.org

Sea Otter Alliance: http://www.seaotterresearch.org/

Sea Otter Research at WERC: http://www.werc.usgs.gov/otters/

Wildlife in B.C. at Risk: http://www.env.gov.bc.ca/wld/documents/otter.pdf 

Note: there are various species of Otter - this is a Fact Sheet about the Sea Otter (Enhydra lutris)

Note 2: This little guy is featured in the latest artwork I’m presently working on (to be a series). Stay tuned for more info (and the big unveiling), but in the meantime, please have a read and ...

~ Be The Change ~