World Turtle Day

Turtles!  Yes, it’s World Turtle Day!  During my herpetofaunal survey I had been lucky enough to find a spotted turtle (Clemmys guttata) right under foot.  In New York, these are a species of special concern.  I’ve spotted painted turtles (Chrysemys picta) in my yard and quite frequently while they were sunning themselves along rivers.  I even came across a common musk turtle (Sternotherus odoratus) during my last kayaking trip. These quiet animals are more common than you might think, if you take a moment to look around.

What the word “turtle” represents actually depends on who you’re talking to and where.  In North America “turtle” typically any reptile with a bony or cartilaginous shell that is developed from their ribs.  It doesn’t matter if these animals are on land or in fresh or salt water.  In Great Britain, though, a “turtle” is one of the water-dwelling species.  A tortoise is a land-dwelling turtle and terrapin is sometimes used to describe small species found in brackish water.  This is just English, mind you, so it can get pretty confusing!  Many scientists refer to the group as chelonian, given that the scientific superorder is Chelonia, just to avoid confusion.  For this post I’ll just stick to “turtle”.

There are over 300 living species of turtles in 14 extant families.  The oldest turtle fossil is dated to 220 million years ago and is one of the oldest reptiles.

Turtles, I think, are most well known for their shells, and these shells go back in time a long ways.  They evolved from the ribs out into plates, and if you ever look inside the shell of a turtle, you can clearly see this.  These shells aren’t always the hard scale covering you’re probably most familiar with though; there are at least 26 soft-shelled turtle species all over the world, in the Trionychidae family.  Their hard shells are covered by leathery skin and the outer edges lack the boney shell underneath.

Turtles lay soft, leathery eggs which are laid in sand or mud, and then covered.  When the eggs hatch the newborns are on their own; neither parent hangs around after the eggs are deposited.  The eggs are susceptible to predation, as are the newly hatched turtles, and some people/organizations collect them for incubation and release, patrol the grounds, and/or protect the newborns as they make their way into the habitat, which is often the oceans, in this case.

While all juvenile turtles are carnivorous, adult turtle diets range depending on the species and habitat.  Some eat vegetation, some, algae, while others eat jellyfish, shellfish, fish, invertebrates, and the occasional carcass.

Turtles have a wide ranging life span depending on species but even the ones with shorter life spans still live many years, which is an important consideration for anyone considering a turtle for a pet.  Larger species can live more than 100 years.  There is some debate as to the oldest recorded animal but Addyaita, male Aldabra giant tortoise, is considered one of the oldest, and he died around the age of 250.

The Speckled Cape tortoise (Homopus signatus) is the smallest turtle, averaging 6-8 cm.  An African species, the females lay only a single egg each year.  The largest species on record is the leatherback turtle (Dermochelys coriacea), a marine species with an individual that measured almost 3m (9ft) in length and weighed 914 kilos (2,016 pounds).  Unfortunately, the animal had drowned in a fisherman’s net..

Not only can marine animals drown in nets but human trash can cause serious problems, such as plastic bags looking like jellyfish and getting caught in a turtle’s throat, or other waste can get caught around their bodies.  Wetland habitats such as swamps are commonly filled in for home and commercial “development,” river and lake-side properties are prime spots for homes, water is often contaminated with chemical pollutants, slow moving turtles get hit by cars, and eggs get preyed on by many animals, including invasive and non-native pets.

As today is World Turtle Day, it’s time to keep in mind that you can make a difference!  Even something small and, I would hope, common sense, such as not running them over, saves a life!

Turtle Crossing!

A Clemson University student conducted research that showed that some drivers purposely hit turtles they see trying to cross the road.  Lend a hand (but watch your fingers) and help turtles safely cross the road!

Defensive Adaptations: Armor

Detachable body parts aren’t the only defensive mechanisms out there.  Actually, the first thing I think of is armor.  Humans have made various kinds of armor to protect themselves for thousands of year, but many animals have evolved to have their own built-in versions.  Millions of years ago there were some serious heavy-hitters in the armor department.  Animals with thick body plates and spikes roamed both the land and the sea.  We no longer have giants like triceratops running around, but we still have armored neighbors.

Crustaceans are an obvious fit in this category, as are most arthropods.  Crabs, lobsters, barnacles, as well as spiders, ticks, insects, etc. have their own armor.  They are all covered in plates of strong exoskeleton.  That’s right, outside skeleton instead of inside.  The strong upper exoskeleton is called the carapace.  In order to grow these animals must shed their skin, or the hard layer of exoskeleton, that they have outgrown.  During this molt the animal is actually quite vulnerable until its new exterior hardens, but when it does it creates some serious protection.

Barnacles are a bit more like turtles and snails in that their bodies, such as head and limbs, are soft flesh but they have a shell that they can pull into.  These shields protect the organs all the time, and the head and limbs when necessary.  The shell is part of the animal in this case, unlike a hermit crab’s shell, which can be replaced with other found shells and at the animal’s discretion. 

A big difference between all of this body armor is the material it is made with.  A turtle shell is actually made of boney plates.  The carapace fuses to the vertebrae of the spine and ribcage.  The exoskeleton of arthropods and crustaceans is made of chitin.  Molluses shells are composed of calcium carbonates.  In all cases it evolved to encase and protect the animal within.

Not to be outdone, there are mammals and reptiles with similar armor.  The New World armadillo has a back full of protective plates meant to defend against predators.  Similar to the turtle, these plates are made of bone and covered with overlapping epidermal scales called “scutes.”  Unlike the turtle, however, armadillos are not covered in an inflexible shell nor are their bellies exposed; their plates are more individualized to allow for more movement and the stomach is soft flesh and fur.  Though the armadillo is known for rolling up into a ball to leave no soft skin exposed, only a few species can actually do this feat, whereas others cannot.

Similar to the armadillo, the pangolin is covered with armor too, but instead of plates it has individual scales that cover its back as well as its limbs and head.  These are not made of bone but of keratin (the same stuff that makes a rhino’s horn or human fingernails).  Like the three-banded armadillo, the pangolin can roll up into a ball as a defense against predators, leaving only it’s hard, pointed scales exposed.

Some lizards, such as the alligator and crocodile, have armored backs.  Here we find both the boney scutes as well as horny scales.  Instead of overlapping like the pangolin scales, the crocodile’s scales are individual square-ish scales set in rows on the body.

A different type of armor altogether is neither scale nor plate but spike.  Several species of lizards have evolved to be covered in spikes, which are actually similar to the crocodile’s scale armor.  These spikes are long, smooth, and pointy, much like those thorns found on a cactus.  Some pufferfish and porcupinefish are similarly covered in spikes.  However, a main differences is that most pufferfish have spikes that lay down flat and only stick up when threatened, as the fish will inhale enough water to make themselves swell into a pointy ball.

This, of course, leads us back into the mammal category where we find the porcupine and hedgehod.  Just like it’s fishy friends, the porcupine has quills/spines that lie flat until the animal is threatened.  These spikes are modified hair made of keratin.  Imbedded in the skin musculature, the animal can raise these quills as needed.  They cannot, however, shoot them like arrows, which is a common myth.  This is armor, after all, which can be used as weapons but is first and foremost for defense.

Canines of Conservation

For thousands of years humans have known that the canine family has them beat in the sense of smell category.  Dogs’ sense of smell, on average, is 100 to 1,000 times better than ours, and depending on the breed, this number can be much higher.  Dogs have been faithful companions to humans for a very long time as they were one of the very first domesticated species.  Often helping with the hunt, these animals have used their powerful sense of smell to aid in locating and retrieving other species.  Now these animals have become many things, including employees.  Their keen sense of smell has been used to sniff out bombs and drugs and some dogs are being trained to sniff out diseases within the human body, such as cancer.

Last week I spoke about Wildlife and Telemetry and how this technology can be used to track wildlife that has been fitted with a transmitter, sometimes over very long distances.  Okay, so what does this have to do with dogs?  You may be surprised.

If dogs are being employed to sniff out drugs and bombs, and are still on occasion being used as hunting companions, we already know what their noses are capable of, and we know that they can find other animals.  This evolutionary skill has now been directed toward aiding biologists in their fight to conserve wildlife.

I’ve only heard, personally, of this being done twice, though that’s not to say there aren’t similar programs elsewhere.  While at a small wildlife conference I attended a gentleman was discussing how his project has trained a dog to locate various species of turtles and to then make his handler aware of their locations.  The dog was trained to find actual turtles, usually hiding under things that would prevent a human from locating them without a very thorough and time-intensive search.  Having done a herpetofaunal survey I can testify to how difficult these animals can sometimes be to find. 

So, why would anyone need to find turtles to begin with?  Well, first and foremost, surveys.  In order to know what’s in an area a survey must be done to identify the species found there.  Once that is done it can be determined how much protection, if any, that location will be granted.  This data can influence building statuses, land purchases, and much more.  Also, sometimes animals need to be removed from a certain area for their own safety, and a sniffer dog can make that search a lot easier.  Being able to locate turtles can also help with other studies, such as allowing them to be found so that a transmitter can be placed on their shell, so measurements and physical data can be collected, etc.

Over at the University of Washington, Professor Samuel Wasser and the University’s Center of Conservation has a team of “Conservation Canines” that aid in research.  They currently have eleven working dogs on their team and each dog has been trained to locate several species, such as wolverines, tigers, owls, bears, wolves, orca, and many more (yes, they can even locate species within water!).

Now, the dogs at the Center of Conservation (which are actually available for hire) have been trained to smell for scat (animal poop), not the actual animal itself.  To explain why this is the focus of the dogs’ training, the Center says:

“Scat (feces) is the most abundant and accessible wildlife product in nature and it contains an enormous amount of genetic, physiological, and dietary information about an animal that can be temporally tied to environmental change.”

The Center uses rescued dogs (huge points for them, in my book) and describes the ideal scat detection dog as a high-energy, obsessive type of dog that could play all day long.  Their reward for finding scat is to play with their favorite toy, usually a ball.

Animals leave scat in locations that they live in or are passing through, and scat won’t run away from you while you’re searching for it.  Once the scat of a certain species is located, researchers can determine the presence of that animal, and can even determine the number of members, and their sexes, of that animal in the area/territory by using DNA testing.  As mentioned in the above quote, scat provides much data for researchers and is far less bothersome to the actual species to locate.

The use of dogs and their powerful noses can and has been a benefit to the wildlife conservation field.  It allows researchers yet another tool to save lives.  It’s a win-win, for the canines and the wildlife, and that’s a recipe for success.