Gharials and Caimans: The other crocodiles

There are 2 other members of the order Crocodilia that are somewhat less well known than crocodiles and alligators:


Gharials- These critically endangered members of the family Gavialidae are characterized by their long, slender jaws. They have many razor-sharp teeth, well adapted to eating fish. They live only on the Indian subcontinent and along with the Saltwater crocodile and the Nile crocodile, it is amongst the largest of all crocodiles, growing to lengths of 20 feet or more.Caiman- South and Central american reptiles that are closely related to alligators. They are amongst the most common of crocodilian species due to their tolerance to both fresh and saltwater.

"Jesus Lizards"

The basilisk lizard, or so called "jesus lizard", has adapted a unique adaptation for escaping predators; running on water!

Because of their relatively light weight and unique locomotion, they are able to run across water for about 15 feet before sinking and having to swim.

Jesus Lizard Video

Venomous snakes

There are 3 varieties of venomous snakes:

Opisthoglyphous snakes: Fixed fangs in the back of the snakes mouth that are angled backward with grooves for delivering venom. Most of these snakes are not harmful to humans, with the exception of the Boomslang.



Proteroglyphous snakes: Fixed fangs in the front of a snake's mouth for delivering highly potent venom. This dentition is unique to elapids, which includes cobras. Some spitting cobras have modified these fangs to allow them to spray venom in attacker's eyes. As shown in this video: Spitting Cobra

Solenoglyphous snakes: Most advanced venom delivery system. Fangs typically folded against the roof of the mouth. When striking, fangs swing into position in order to inject venom. The venom is typically less potent than proteroglyphs, but solenoglyphs are capable of injecting much more venom. This type of dentition is unique to vipers.

The most venomous snake in the world is the Inland Taipan. One bite from this snake is enough to kill approximately 100 people or 250,000 mice! This is 50x more potent than a King Cobra.

Largest and Smallest

Largest:
Crocodile: Saltwater Crocodile, 13-18 feet long and 1300- 2000 lbs. (Largest ever was 20 feet long and 2900 lbs!)
Lizard: Komodo Dragon, 6.5-10 feet long, 150 lbs
Snake: Most Massive:Green Anaconda, 23 feet long, 550 lbs
Longest: Reticulated python, 28 feet long
Largest Venomous (overall): South American Bushmaster, 12 feet long, 19 lbs.
Longest Venomous: King Cobra, 18.5 feet long
Heaviest Venomous: Eastern Diamondback rattlesnake: 26 lbs
Turtle: Leatherback Sea Turtle: 9 feet long, 2000 lbs
Tuatara: Brother's Island Tuatara: 30 inches long, 3lbs

Largest Reptile ever: (based on one vertebra) Amphicoelias: 60 meters long, 122 metric tons! (Link shows in comparison to 6 foot human)

Smallest:
Crocodile: Cuvier's Dwarf Caiman: 5 feet long
Lizard: Jaragua Sphaero, 16- 18 millimeters (Can curl up and fit on a dime!)
Snake: Barbados Threadsnake, 10 centimeters long
Turtle: Speckled Padloper Tortoise, 2-3 inches long, less than 100 grams (the weight of a medium sized tomato)

Testudines

Testudines, or turtles and tortoises, have been called a variety of names over the years. Other family names include Chelonia, Chelonii, and Testudinata. Testudines are roughly 215 million years old, making them one of the earliest reptile groups, older than both snakes and lizards.

There are several distinct autapomorphies, or characteristics that distinguish a species from another, that all testudines share:

• The most easily recognized is a hard, bony shell that encloses both limb girdles. The shell is composed of both specialized vertebrae and ribs. The top of the shell is called the carapace and the bottom of the shell is called the plastron.
  
• A lack of teeth
• Hip and shoulder bones are located inside the rib cage, since it makes up the shell

Interestingly, fossils from Olduvai Gorge, one of the locations with the earliest human fossils, indicate that turtles have been a food source for humans for roughly 2 million years. Humans have dramatically affected the populations of testudines, especially land tortoises, with many different species driven to extinction.

Crocodiles vs. Alligators

There are a few key differences between alligators and crocodiles that make them easily distinguishable.

First of all, Crocodiles and Alligators are part of 2 separate families, Crocodylidae and Alligatoridae respectively.

Crocodiles have a long, narrow, V-Shaped snout. Alligators have a wider. U-Shaped snout:

The alligator's wider snout allows for more crushing power; strong enough to crack turtle shells. The crocodile's narrow snout is less equipped for cracking turtle shells, but still very powerful, capable of bite strengths of 5,000 lbs/square inch.

Another difference between alligators and crocodiles is the presence or absence of viewable teeth. Crocodile's top and bottom teeth are viewable from the side, whereas alligator's bottom teeth are not.



In general, alligators are smaller and more docile, if you consider 14 feet small compared to the 19 feet of a crocodile, which are comparatively more aggressive.

Alligators which appear black are generally darker than crocodiles, which have an olive brown hide.

Tua-what-a?

Tuatara (n.)- Maori word for "peaks on the back"

The Tuatara is a 200 million year old native of New Zealand that closely resembles a lizard. Though they resemble lizards superficially, that is about all they have in common. The tuatara is considered the most unspecialized living amniote, and can live 60-100 years in the wild. It's brain and mode of locomotion is like that of amphibians, it has a more primitive heart than any other reptile, very primitive hearing, and their lungs have only one chamber and no bronchi. The peak activity levels for tuatara is between 12 and 17 degrees Celsius, the lowest of any reptile.

The tuatara has unique dentition. The lower teeth fit into a groove between 2 rows of upper teeth. This isn't seen in any other animal in the world.

The tuatara has a parietal or third eye on the top of its head. It grows under the skin of adults and some scientists argue it serves no function, though it's retina and rudimentary lens suggests it affects the hibernation and sleep cycle of the tuatara.

For all these reasons, the tuatara is especially of interest to evolutionary biologists, since they serve as a "living fossil" that can help scientists understand the evolutionary relationships between living reptiles, as well as extinct orders of reptiles. The tuatara is the only living member of the order Rynchocephalia.

Warning Coloration

In nature, animals will use bright colors to warn other organisms that they are distasteful or potentially dangerous (Like the Gila Monster pictured above). Bright colors like red, yellow, or orange are typically seen. In something called Mullerian mimicry, venomous or poisonous animals that are unrelated share warning coloration. An example of this is wasps and hornets or butterflies.

Interestingly, another type of mimicry is Batesian mimicry, where a harmless animal mimics the coloration of a dangerous animal. A great example of this is the Coral Snake and the Milk Snake. Both have red, black, and yellow coloration though only 1 is venomous.

The adage used to determine the difference between the two is:

If red touches yellow, you're a dead fellow
If red touches black, you're okay, Jack

This means if the red coloration touches a black band of coloration the snake isn't venomous, but if the red coloration touches a band of yellow coloration the snake is.

Which of these 2 snakes would you expect to be venomous?

A)
B)

Dinosaurs with feathers?

Birds are the closest living relatives to dinosaurs, the reptiles that lived over a 100 million years ago. But did you know that some early dinosaurs also had feathers?

It is now believed that the Velociraptor*, made famous by Jurassic Park, may not have been only been feathered, but also may have been venomous. They had long rear facing fangs with grooves in them that closely resemble fangs seen today in venomous snakes and lizards. Link here.

*Interestingly, the Velociraptor on screen was modeled on the species Deinonychus

ReptileBlog

Over the course of the next 2 weeks, I'll be updating this page with interesting facts and information about reptiles, such as snakes, lizards, crocodiles, etc. Though "reptiles" is no longer a valid taxonomic term (since it is paraphyletic), it is highly unlikely that the term will ever go away.

There are 4 living orders of reptiles:

Crocodilia: Includes crocodiles, alligators, gavials and caimans

Sphenodontia: Tuataras

Squamata: Snakes and Lizards

Testudines: Turtles and Tortoises