Feeds:
Posts
Comments

Archive for the ‘Reptiles’ Category

I’ve been watching a heap of dissection documentaries recently for free on YouTube via a user named EvolutionDocumentary. They’re from the series with Richard Dawkins named Inside Nature’s Giants. It’s a paid account so all the documentaries are full length (no irritating 10 minute splits) and they have no ads either. WIN!

It’s incredibly interesting stuff so I definitely recommend having a look, and to make things easier I’ll relink them all here in sequential order.

Read Full Post »

These guys are seriously unique in appearance… I’ve never seen anything like them! The Red-eyed Crocodile Skink, Tribolonotus gracilisis from the forests of New Guinea and is one of the few known lizard species that vocalises when in distress.

Interestingly, females of the species only have a single working ovary (the right ovary), and can only lay a single egg at a time. They also apparently exhibit mother-child family group tendencies. They have some frickin’ awesome armour on their backs as well!

Read Full Post »

Read Full Post »

A leucistic green sea turtle (spotted on r/pics).

On first appearances I’m sure the majority of us would proclaim with interest and enthusiasm, “WOW! An albino green sea turtle.” However, that isn’t the case interestingly enough! It’s actually a turtle with what’s known as leucism. According to wikipedia:

Unlike albinism, it is caused by a reduction in all types of skin pigment, not just melanin.

From my understanding, the best way to tell the difference is by looking at other parts of the body like the eyes (leucism can also be patchy in appearance where only some parts of the animals skin is affected). Melanin is the only pigment that contributes to eye colour (in the iris specifically), and hence why it’s possible to detect the difference between these two genetic disorders. (However, this method isn’t necessarily fool proof as I’m sure pigmentation attributed to melanin may vary a great deal across many different species, so genetic tests would probably be the only thing that is truly fool proof when it comes down to it).

A leucistic pigeon (not the normal coloured eyes and legs, and patches of normally coloured feathers).

In the below example using the alligator, when the eyes appear as they normally do, with grey/blue pigmentation, the animal is most likely leucistic, and if it has pink eyes lacking melanin pigmentation then it’s an albino.

A leucistic alligator

An albino alligator

People may ask why traits like albinism or leucism still exist in the wild when surely it has little if any benefits for animals? Evolution via natural selection unfortunately finds it relatively impossible to weed out traits like albinism and leucism which are recessive. That is that they aren’t exhibited by the animal (in what’s called its phenotype) unless the animal has two copies of the recessive alleles (one from its mother and one from its father). If it only has one, it will exhibit the same phenotype (it will appear the same) as would an individual without any copy of that allele.

Because of this fact, individuals who carry two alleles and appear white are likely to have a lower fitness level than other normally appearing individuals, and is thus more likely to be killed/predated prior to passing on its genes. However, because individuals can carry a single recessive allele for albinism or leucism without any changes to its appearance, if it ever mates with another individual who is carrying a single (or two) recessive alleles then offspring may be produced carrying this phenotype. Similar to genetic disorders in humans such as cystic fibrosis or sickle-cell anemia.

On a side note, during my volunteer work in Queensland at Mon Repos with sea turtles, I would often find white hatchlings. Unfortunately, the majority of them normally didn’t make it out of their shells and died in the burrows as a result of other genetic defects they also carried (they often had contorted bodies, and one I found had no eyes at all). In once case I even found twin albinos sharing a single egg shell. Sometimes you’d find abnormally large eggs an these would have two yolks or embryos in them. It was rare enough that they would actually develop at all, let alone develop and both be albino or leucistic.

Looking back I wish I’d had a closer look and could’ve worked out whether they were carrying albinism or leucism! I might have to rummage through my turtle photos and see if I can find some images of them.

Green sea turtle hatchlings, clearly some can survive, but also note the distortion of the vertebral scales along the spine of the white hatchling (though this is often seen on average hatchlings too).

Read Full Post »

This is the tail of a Eulamprus tympanum tympanum from an individual my friend caught during her MSc in East Gippsland. It was caught in a pitfall trap, and when she pulled it out to have a closer look she noticed something a little peculiar about its tail.

Skinks are a family of lizards, Scincidae, and are renowned for their ability to drop their tails when threatened or caught by predators in an attempt to distract them and escape. The tails once lost grow back much the same as the old tail but with the new vertebrae grown out of cartilage.

Anyway, as usual this individual grew back its tail after having dropped it for whatever reason, and through some physiological mistake it grew a second tail end out of one side of its main tail.

Read Full Post »

A new species of sea snake has been found in Queensland reports this article from Science News.

A paper, published yesterday in the journal Zootaxa, announces the discovery and notes that the new species called Hydrophis donaldii is unique in having raised scales.

H. donaldii had evaded earlier discovery as it prefers estuarine habitats that are poorly surveyed and not targeted by commercial fisheries”, explained Dr. Bryan Fry, a co-author on the discovery paper and an Associate Professor at the University of Queensland’s School of Biological Sciences.

The scientists collected nine specimens of this ‘viviparous or true’ sea snake from the coastal estuarine habitats of Weipa on the Queensland coast of the Gulf of Carpentaria.

“Weipa really is one of the last sea snake ‘Serengetis’. We can see over 200 sea snakes in a single night’s hunting, whereas sea snake populations have really crashed elsewhere through over-fishing removing their prey and also the snakes drowning in trawling nets.”

“All venomous animals are bio-resources and have provided sources of many life-saving medications, such as treatments for high-blood pressure and diabetes. This reinforces why we need to conserve all of nature as the next billion dollar wonder-drug may come from as unlikely a source as sea snake venom.”

H. donaldii is named in honor of David Donald, Dr. Fry’s long-time boat captain.

“Quite simply we would not have found this snake without Dave’s unique knowledge of the area. I told him we wanted to survey as many distinct types of habitat as possible and he guided us to the perfect spots,” Dr. Fry said.

It is also given the common-name ‘rough-scaled sea snake’ to reflect the unique scalation.

“We don’t know why it has been evolutionarily selected to have such unique scalation, but we will next study its ecology to learn more about it,” the scientist concluded.

Read Full Post »

This is a species of viper, a venomous snake, found in Central Africa. Scientific name is Atheris hispida, common names include rough-scaled bush viper, hairy bush viper or spiny bush viper (for obvious reasons). It has some impressive keeled scales that almost give it a bristly appearance. They probably help a great deal with camouflage in vegetation, by breaking up the outline of the animal as well as giving it a leafy appearance.

Read Full Post »

Older Posts »