After 200 million years, all-male future spells doom for reptiles

by amyjudd | July 3, 2008 at 02:16 pm | 1109 views | 34 comments

Tuatara - prehistoric reptile unique to NZ - takes 35 years to reach the full size of 24 inches and takes one breath an hour

A group of reptiles called tuataras, the only surviving order that were around when dinosaurs roamed the earth could be wiped out because climate change could turn all the eggs into males - causing them to not be able to reproduce.

The gender of tuataras, an ancient type of reptile with three eyes, is determined by the temperatures that the embryos are kept at when in the egg. Global warming means that the reptiles, regarded as living fossils, face the threat of dying out in the wild because of a terminal shortage of females.

Only males will be born in nests where the eggs have been kept at temperatures of 22.25C (72.05F) whereas females are guaranteed only at temperatures lower than 22.1C.

Modelling showing the likely impact of climate change on the last remaining homes of tuataras showed that the last female could hatch by 2085 for at least one of the two surviving species.

Tuataras evolved 225 million years ago. The two remaining species cling on to survival in New Zealand and are regarded as among the oddest reptiles. They have a mysterious third eye at the top of their heads, are able to hold their breath for an hour and, despite their cold-blooded nature, are nocturnal.

Until rats and other mammals - introduced by humans - arrived, the reptiles were widespread in New Zealand but they are now found only on a handful of small islands safe from the mainland.

With climate change, average temperatures are expected to rise by up to 4C (7.2F) by 2085, which would be enough to ensure that all the North Brother Island tuataras, Sphenodon guntheri, are hatched male. The other species, the Cook Strait tuatara, S. punctatus, could follow soon afterwards.

Stories like this just make me so sad.

The tuatara is an amniote of the family Sphenodontidae, endemic to New Zealand. The two species of tuatara are the only surviving members of the Sphenodontians which flourished around 200 million years ago,[1] and are in the genus Sphenodon. Tuatara resemble lizards, but are equally related to lizards and snakes, both of which are classified as Squamata, the closest living relatives of tuatara. For this reason, tuatara are of great interest in the study of the evolution of lizards and snakes, and for the reconstruction of the appearance and habits of the earliest diapsids (the group that additionally includes birds and crocodiles).

Tuatara are greenish brown, and measure up to 80 cm (32 in) from head to tail-tip[2] with a spiny crest along the back, especially pronounced in males. Their dentition, in which two rows of teeth in the upper jaw overlap one row on the lower jaw, is unique among living species. They are further unusual in having a pronounced parietal eye, dubbed the "third eye", whose current function is a subject of ongoing research. They are able to hear although no external ear is present, and have a number of unique features in their skeleton, some of them apparently evolutionarily retained from fish. Although tuatara are sometimes called "living fossils", recent taxonomic and molecular work has shown that they have changed significantly since the Mesozoic era.

They have a really rare 'third eye', which makes them even more unique and special.

The ‘third eye’ is visible under young tuatara’s skin and becomes covered with scales after four to six months. The ‘third eye’ soaks up UV (ultra violet) rays in the first few months of the tuatara’s life. The young tuatara get Vitamin D from the UV rays, which helps them grow into healthy adult tuatara.

Some weird facts about them:

They are capable of holding their breath for nearly an hour

Tuatara have one of the slowest growth rates of any reptile

Tuatara keep growing until they are about 35 years old

They will share burrows with birds, but a male might bite off a baby bird’s head if it is hungry – which doesn’t make it a very good house guest!

Male tuatara can weigh up to 1500grams

A tuatara’s average life span is about 60 years but they can live to be over 100 years old

At an average of 50cm long, the tuatara’s size today is maybe only half of what it once was

Like other reptiles, tuatara are cold-blooded, which means their temperatures change with the air temperature.

Tuatara are nocturnal and prefer cool weather. However they will often bask in the sun to warm their bodies – but they are careful not to over-heat.

Young tuatara usually hunt for food during the day – to avoid being eaten by adult tuatara at night!

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hikes

at 15:01 on July 3rd, 2008

good stuff:

Thanks for posting this!

By the way, that's so sad.

Disdainful Soul

at 21:02 on July 3rd, 2008

good stuff:

amyjudd, more people should know about the tuatara and how it's a shame that global warming is contributing to their eventual end.

BrendonPG

at 21:34 on July 3rd, 2008

They've been around for 200 million years, so I find it hard to believe a little climate change will affect them. They must be tough and survivors like all New Zealanders.

BrendonPG has contributed a photo to this story.

niel.changco

at 21:57 on July 3rd, 2008

This tuatara was photographed from the Karori Wildlife Sanctuary, Wellington. They are really unique creatures!

niel.changco has contributed a photo to this story.

PicArt by Mike

at 22:27 on July 3rd, 2008

This Tuatara was photographed at the Mt Bruce Conservation Centre in the Wairarapa.

PicArt by Mike has contributed a photo to this story.

nzPaul

at 23:36 on July 3rd, 2008

nzPaul has contributed a photo to this story.

simonech

at 23:46 on July 3rd, 2008

That was taken at the Karori Wildlife Sanctuary in Wellington, where they live kind of free

simonech has contributed a photo to this story.

Adrian Rumney

at 00:20 on July 4th, 2008

Tuatara at Karori Wildlife Sanctuary in Wellington. The coloured beads on the neck are used to identify individuals.

Adrian Rumney has contributed a photo to this story.

b34r.girl

at 00:51 on July 4th, 2008

This tuatara photo was taken at the Karori Wildlife Sanctuary in Wellington, New Zealand.

They have a decent size enclosure that enables them to roam relatively free and visible to the general public.

b34r.girl has contributed a photo to this story.

Mr Gray

at 01:53 on July 4th, 2008

This photo was taken at the Karori Sanctuary in Wellington.

Mr Gray has contributed a photo to this story.

ejbluefolds

at 03:59 on July 4th, 2008

On my first trip to New Zealand, I came across the tuatara and was fascinated with this ancient reptile. On speaking to the people looking after them I was told that they lived a very long time and that this one was more than 80 years old. I took 2 photos at the Museum at Invercargill.

ejbluefolds has contributed a photo to this story.

Wilfredo Falcón

at 04:37 on July 4th, 2008

This picture was taken in the Tiritiri Matangi Island Open Sanctuary, off the coast of Auckland, NZ. It's a fascinating place to experience the wildlife, especially the tuataras. I had a great experience volunteering with the NZ Conservation Department.

www.tiritirimatangi.org.nz/

Wilfredo Falcón has contributed a photo to this story.

digitaltrails

at 05:03 on July 4th, 2008

New Zealand has a variety of climates and terrain. Perhaps we may be able to move these creatures to somewhere more comfortable for them. At the moment they only exist in a few protected islands and reserves, so relocation might be quite feasible. I sure hope so.

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azzayindia

at 08:37 on July 4th, 2008

good stuff:

amyjudd, I like this story. It's good stuff.

alumroot

at 09:03 on July 4th, 2008

In two hundred million years, climate has changed and set point for temperature dependent sex determination has changed with it. The key to their survival will be how quickly that set point changes, and if there is sufficient variation in this small population so the change is possible.

dunkelberg

at 10:07 on July 4th, 2008

Perhaps, but the study in question says it is unlikely, as one population already faces a extreme maie bias.

dunkelberg

at 13:17 on July 4th, 2008

good stuff:

amyjudd, I like this story. It's good stuff.

zusjes weblog

at 15:31 on July 4th, 2008

These were taken at the museum in Invercargill. I seem to remember that there was a news item not too long ago that their male Tuatara had found a mate so there might me little Tuatara's in the near future (for Tuatara near might be a bit longer for us).
I have also seen a Tuatara couple on Tiri Tiri Matangi where they are monitored. So it is not all gloomy and there is some hope.....

zusjes weblog has contributed a photo to this story.

zusjes weblog

at 15:32 on July 4th, 2008

good stuff:

amyjudd, I like this story. It's good stuff.

NP_1_811954

at 03:44 on July 5th, 2008

The photo of the baby tutara in a woman's hand was taken at the Wellington zoo shortly before the Tuatara were released on Stevens Island.

Jeremy Rose

NP_1_811954 has contributed a photo to this story.

Miraz

at 13:35 on July 5th, 2008

This photo was taken at the Karori Wildlife Sanctuary in Wellington just after arriving from the island it grew up on and before being settled in to its new enclosure.

Miraz has contributed a photo to this story.

ryanja

at 18:58 on July 6th, 2008

This is Henry, the oldest Tuatara in captivity.

ryanja has contributed a photo to this story.

Liz Headland

at 22:43 on July 6th, 2008

Taken at the Invercargill Museum, December 2007.

Liz Headland has contributed a photo to this story.

Liz Headland

at 22:46 on July 6th, 2008

Photo's taken at the Southland museum, Invercargill, Dec 2007

LiveDave

at 23:15 on July 6th, 2008

One of the larger tuataras we have ever come across, but we were eventually able to tame and ride it.

LiveDave has contributed a photo to this story.

jennywo

at 08:29 on July 7th, 2008

I took this photo in Queensland, New Zealand at the bird park, there. I was there for an ECO Challenge adventure race with Seagate Technology, February 2007.

Please, provide proper credit if publishing this photo. It was taken by me, Jenny Wood.

Thank you,
Jenny

jennywo has contributed a photo to this story.

kitjaguar

at 14:37 on July 7th, 2008

kitjaguar has contributed a photo to this story.

DLSlater

at 17:42 on July 7th, 2008

We took this photo at the Rainbow Springs Nature Park in Rotorua, New Zealand in April 2007.

DLSlater has contributed a photo to this story.

ruthvansickle

at 07:29 on July 9th, 2008

This photo of Henry was taken at the Southland Museum in Invercargill, NZ. I lived in Invercargill for 7 months and had to revisit the museum a few times before I got a glimpse of Henry. He finally came out my third visit and I was able to get a few good photos of him.

ruthvansickle has contributed a photo to this story.