Sex and the single snake - who needs males?

From Wikipedia

Female reptiles don't always need to mate with males to have offspring. Snakes, Komodo dragons, and lizards have all given birth without sex. These have been females that were kept in zoos, labs or homes, and for some time people thought that parthenogenesis, the scientific name for virgin births, was the just effect of captivity.
But did this happen in the wild? It was difficult to know because some females reptiles can store male sperm for months or years, presumably waiting for a good time to be pregnant, ie a time when there is plenty of food and the right environment. So just because a wild reptile seemed to give birth without mating, it wasn't necessarily so. It was just delayed ordinary conception.
Then scientists, led by Warren Booth, examined 22 litters from broad banded copperhead snakes, A. contortrix,  and 37 litters from pit vipers, A. piscivorus, all from pregnant females collected in the wild. They did a DNA analysis and concluded this was automictic parthenogenesis. This probably means that when the original reproductive cell splits into two, the two new cells merge with each other and then start reproducing themselves (if I understood the process correctly).  The parthenogenesis found in reptiles like a blind snake and some lizards who automatically practice virgin birth is different and I will blog about this later.
This means that if a female snake or lizard cannot find a mate, she can give birth anyway. Aren't reptiles fascinating?  We mammals can't do this!

For more details read: Booth, W., Smith, C., Eskridge, P. H., Hoss, S. K., Mendelson, J. R. & Schuett, G.W., (2012), 'Facultative Parthenogenesis Discovered in Wild Vertebrates', Biology Letters, doi:10.1098/rsbl.2012.0666

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Why is your snake fainting?

A Youtube video of the death feint https://www.youtube.com/watch?v=9pm6hsIDXVc

The snake you are handling or are about to handle, suddenly goes limp and faints. It looks completely dead but it isn't. This is what Darwin called "the death feint." Or playing dead - though this is far from being a game for the snake.
The modern scientific term for it is "tonic immobility." Many animals including other reptiles and rabbits faint like this.
If an animal faces intense danger then an automatic reaction kicks in. There is a huge surge of adrenaline (epinephrine) and a reaction with what is commonly known as the five "Fs" - flee, fight, freeze, faint or fool about (ie do something odd which distracts the predator). Faced with being handled, a captive snake hasn't got the option to flee or to fight a large human. So fainting is one of the options left to it.
This death feigning reaction sometimes looks like a relaxed animal and ignorant rabbit owners think the rabbit is enjoying it.  Far from it. Rabbit owners are beginning to recognise this, as should snake owners. If your snake goes limp it is in utter terror.
Fainting is a last resort for an animal faced with a dangerous predator. With luck the predator will think the snake is dead and for a moment shift it's attention elsewhere. Then the snake has a chance to escape. This may work, for instance, with predators like the domestic cat.  If you watch a cat "playing" with a living mouse, when the mouse goes immobile the cat stops play for a little while. A cat's predatory drive is turned on by movement so sometimes the cat will poke the mouse to make it move so the play can continue. Cats that catch snakes often do a similar kind of playing around.
Patrick Gregory of Kent University tested the response of grass snakes to being captured. Snakes that were held by the tail rarely fainted when first grasped. Those held by the head were more likely to feign death. The larger the snake the more likely it was to remain immobile after being released. Perhaps because bigger snakes have less to fear about remaining still. The snakes that didn't faint would usually slither away as soon at they were released.
* More info at  Gregory, P. T., (2008),  'Bluffing and waiting: Handling Effects and Post-Release Immobility in a Death-Feigning Snake (Natrix natrix)', Ethology, 114, 768-774.

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The tortoise shell - an amazing story of evolution.

An early fossil of a tortoise that lived in South AFrican 260 years ago has been discovered. It has no shell though it shares other anatomical features with modern tortoises.  About 50 million years later fossils of tortoises with shells start to appear.
Dr Tyler Lyson of Wits University's Evolutionary Studies Institute, the Smithsonian Institution and the Denver Museum of Nature and Science explained: "Tortoises have a bizarre body plan and one of the more puzzling aspects to this body plan is the fact that tortoises have locked their ribs up into the iconic tortoise shell. No other animal does this and the likely reason is that ribs play such an important role in breathing in most animals including mammals, birds, crocodilians, and lizards."
Dr Lyson and his colleagues have shown that the modern tortoise breathing apparatus was already in place in the earliest fossil tortoise, an animal known as Eunotosaurus africanus.
This new species bridges the gap between the earliest proto tortises and the hard shelled tortoise of modern times.

This is how the hard carapice of the tortoise developed over the years. Watch the video here.

Download and read the scientific paper here: Tyler R. Lyson, Emma R. Schachner, Jennifer Botha-Brink, Torsten M. Scheyer, Markus Lambertz, G. S. Bever, Bruce S. Rubidge, Kevin de Queiroz. Origin of the unique ventilatory apparatus of turtles. Nature Communications, 2014; 5: 5211 DOI: 10.1038/ncomms6211
Or there is an easier version here.
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Do you want a huge iguana living in your garden?

Green iguana - Wikipedia

Iguanas are moving into Florida thanks to its subtropical climate. They have also invaded Hawaii. These lizards are the descendants of pets that have been released into the wild. It is illegal to let them go but people still do it.

Mexican spiny iguana- Wikipedia

Now there are three species flourishing in south Florida - the common green iguana which can grow up to two metres long and weigh six or more kilos, the Mexican spiny-tailed iguana, which grows up to 1.3 metres long and the black spiny-tailed iguana about the same size but known as the fastest lizard in the world. The latter can look rather like alligators to people who are not familiar with the species.

Black spiny iguana - Wikipedia

Iguanas are herbivores mainly thought they will eat insects, birds eggs, and small animals. They will be happy to eat roses, bougainvillea, green vegetables, and courgettes from a garden.They burrow under pavements, leave droppings that may carry salmonella, and cause severe wounds by scratching and slapping their tails if people try to pick them up.

More details here
With thanks to Richard Adams, whose blog put me on to this. www.KeepingExoticPets.com
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This amazing croc comes from Crocodiles of the World, a really good "zoo" that specialises in crocodiles and reptiles. Nothing else.
It is a zoo run by madly enthusiatic people , which grew out of one person's love for and obsession with crocodiles.  If you live in Oxfordshire you should make sure you don't miss it. A great place for kids too. Details at www.crocodilesoftheworld.co.uk
What I find weird about the crocodiles is their stillness. They are fast enough to pull down animals that come to the water to drink, but when they are not doing this they seem almost immobile. It's a great way to save energy. We could learn from them!
Did you know...

• Crocodiles can swim at 25mph just with the help of their powerful tail.
• Farmed crocodiles can reach 1.5 metres (5ft) in length in just one year.
• They sweat through their mouths.
• They have 24 teeth that are meant to grasp and crush, not chew. Like birds swallow grit, they swallow stones that grind food inside their stomachs, and also act as ballast.
• Most crocodile babies are eaten in the first year after birth, by large fish, herons, monitor lizards and even adult crocodiles.
• Some tribes in New Guinea, venerate the crocodile and give themselves scarring to match that of a crocodile skin.
• Crocodiles, first appeared 240 million years ago,
• They  can live up to 80 years.

PS. Crocodiles of the World is warm and sweaty just as crocs like it. If it's raining outside or cold, this is a great place to visit!

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New crocodilte species found in South Pacific - alas extinct. We probably ate it.

wikopedia

We are still finding the remains of large extinct animals - and this is one of them, the Mekosuchidae crocodile family (or, to be technical, possibly just a sub-family). This group includes one species which may have been a tree climber!
Mekosuchus kalpokasi the latest fossil discovery was a small croc, possibly one that lived on land rather than in the water. It was probably hunted to death when humans arrived three thousand years ago.
The jawbone was found in one of the islands of Vanuatu, (formerly the New Hebrides), 82 islands just southeast of the Solomon Islands. There is disagreement where the Meksuchian crocs fit into the family tree of crocodiles partly because there are only rare finds, though we know at least three species inhabited the South Pacific. Many species of crocs can live in the sea because they have salt glands in the tongue which can excrete the salt. So these kinds of extinct cros may have island hopped their way from Australia at a time when the sea level was lower and many small islands and coral reefs were above land.
Why is is extinct? Probably because the Lapita people arrived on the island and hunted it to extinction. Its remains were found at an archeological site suggesting that it was a food animal for the human arrivals. More detail here:

• Mead et al., (2002), 'New extinct Mekosuchine crocodile from Vanuatu, South Pacific,' Copeia, vol 2002, 3, 632-641. With thanks to Matthew Spriggs, one of the authors.

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