Basic Reptiles Info
Reptiles
-includes snakes, lizards, crocodiles, turtles, and tuatara
-Cold blooded, egg laying vertebrates with scales or scutes rather than fur or feathers.
-they are an ancient group of vertebrate animals with fossils dating back over 300 million years ago.
-The overall global status of reptiles is unhealthy with many species in decline
Lizards
-Scaly reptiles, very diverse group
-usually have 4 legs, long bodies, tails, eyelids, external ears
-example: geckos, iguanas, skinks, chameleons
Turtles
-Are an ancient group
-unique shells that protect their bodies
-they lay eggs on land and breathe air
-example: sea turtles, fresh water turtles, land-based tortoises
Crocodiles
-they live a semi-aquatic life style
-they hunt in the water
-very solid animals with short limbs and large flattened mouths
Snakes
-limbless, evolved from lizards
-carnivorous
-600 of the 3500 species are venomous
Tuatara
-Sphendon punctatus
-Sole surviving species from ancient lineage of animals
-only found in new Zealand
Basics on lizards
Where are they found?
-everywhere on earth except Antarctica
-They are cold blooded so they are prevalent in warmer climates; tropics and deserts
-The amazon is the diversity hot spot with more species than anywhere else.
-Australia is home to more than 620 species and more than 600 species in southern Africa
Size
-sizes of different species vary drastically
-smallest is the Brookesia Micro of Madagascar, full grown at 29mm
-largest is the Komodo dragon of Indonesia, full grown at 10 ft and 155 pounds.
What do lizards eat?
-many are herbivores
-some are carnivorous
-and some are omnivores
-it all depends on the species
How do lizards reproduce?
-It all depends on the species, they either lay eggs of give live birth
Taxonomy of lizards
-Lizards belong to an order of reptiles known as the Squamata which includes snakes
-within the lizard group there are 4 infaorders
-Iguania: separated into many families including iguanas, chameleons, and more
-Gekkota: 6 families including 2 families of geckos
-Scinomorpha: includes skinks, wall lizards and more
-Anguimorpha: 6 families including anguidae family which has many legless lizards
-Amphisbaenia: the worm lizards, 5 families with species that look like earth worms.
Diversity and evolution of lizards
-More than 5000 species
-largest diversity of any reptilian group
-make up over half of all reptiles species
-largest genus of lizards is a genus of iguana known as anola with more than 400 species
-known to have evolved more that 200 million years ago (100 million years before mammals)
-lizard like fossils date back to the Triassic period 252.2-201.3 million years ago
Interesting Facts
-They shed their skin
-some can drop their tail and regrow it
Because they are cold blooded they are unable to move quickly when it is cold due to their slowed down metabolism
Basics on Turtles
-evolved 200 million years ago
-220 living species (tropical and subtropical climates)
-they provide no parental care
-only 1 in 1000 turtles survive to adulthood
-they are the longest living animals on earth, living well over 100 years
Turtle Shells
-protection from predators
-shell is fused with ribs and spine
-top half of the shell is called the carapace
-bottom half is called the plastron
-The carapace and the plastron are connected by bony structures called bridges
-The carapace is usually covered by scales called scutes
-These scutes are helpful with identifying different species
-The shape of the shell usually is a reflection on their environment
-land based tortoises have domed shaped shells
-sea turtles have lower shells to reduce drag as they swim
Soft shelled turtles are very fast, due to lighter shells and webbed feet.
Turtle Physiology
-They spend their time basking in the sun in order to warm their body and increase their metabolism
-A turtles shell constricts the expansion of the ribs for breathing, turtles overcome this problem with muscles that increase the space surrounding their lungs as they breathe in.
-This provides room for the lungs to expand the muscles then squeeze the same space and cause air to be forced back out of the lungs as they breathe out.
-A turtle’s heart have the ability to control whether blood is sent to the lungs or the rest of the body.
-Depending on the importance of oxygen uptake or temp regulation at any given time the heart will send more blood to the lungs or to other parts of the body.
Sea Turtles
-Out of the 220 species only 8 live in the sea
-Black sea turtle, flat-back sea turtle, green sea turtle, hawksbill sea turtle, kemp’s ridley sea turtle, leatherback sea turtle, logger head sea turtle, and olive ridley sea turtle.
Tortoises
-A group of land based turtles
-they are from the Testudinidae family
-generally only enter the water to drink or bathe
-they are extremely long lived
-some are known to live over 150 years
Interesting Facts
-gender of a turtle is determined by the temp the eggs are incubated at.
-global warming is causing a sex ratio problem, more females are being born relative to males.
-A musk turtle is able to climb trees
-The leatherback turtle is the largest and can weigh more than 1300 pounds.
Basics on Crocodiles
-They are an ancient group of animals
-their greatest diversity was back in the cretaceous era (145-66 million years ago)
-there are currently 23 different species
-They are in the order crocodilian
-which includes 3 families
-Alligatoridae (alligators and caiman)
-crocodylidae (true crocodiles)
-gavialidae (gharial)
Hunting and Diet
-They stalk their prey from the water
-Some ambush their prey as they drink or bathe
-Some species are able to kill and eat large mammals like zebra, wildebeest, and humans.
-Once they catch their prey they drown it. Then they take large bites and swallow it whole.
-Other species such as Chinese alligators and gharial feed primarily on fish or invertebrates
Parental care
-They are caring parents, both males and females play a role
-Some help their hatchlings from the eggs
-American alligators carry their hatchlings to the water 1 or 2 at a time
True Crocodiles
-found in tropical regions of the Americas, asia, Australia, and Africa
-most live in freshwater, some are found in salt water
-many are currently endangered
-The saltwater crocodile (crocodylus porosus) is the largest in this family
-it can grow to 23 feet and 2300 pounds
-unfortunately there are none alive at this size, they grow very slowly and are usually hunted down long before they reach this size
Alligators and Caimans
-2 species of alligators and 5 species of caimans make up the family Alligatoridae
-They live in fresh water
-They can be distinguished from crocs by their ‘U’ shaped snouts
-Excluding Chinese alligators, the alligators and caimans are new world animals found in the Americas and the Caribbean
-American alligator is found in the united states along the gulf coast, caimans range from Mexico through the Caribbean and into south America
-They range from 4-16 feet
-Black caiman (melanosuchus niger) is the largest species in the family
Chinese alligator only grows to an average of 5 feet
Gharial
-Sole remaining species from the family gauialidae
-found in northern India through to Burma
-second largest species of crocodile behind the salt water crocodile
-feeds on fish
-narrow snout with sharp interlocking teeth, handy for catching its prey
Interesting Facts
-crocodiles are more closely related to birds than any other group of animals
-the gender is determined by the temp the eggs are incubated at
Basics on Snakes
Where are snakes found?
-They are found on 6 continents
-uncommon in the arctic
-not found in Antarctica, Iceland, or Greenland
-they have never colonized in Ireland or New Zealand
-cold blooded, found in warmer places, not typically found in alpine areas
-found in forests, tropical forests, grassland environments
-snakes (and other reptiles) are the most successful vertebrate animals in the harshest environments, deserts
-they can be found on land, in the sea and some species dwell in both
How old are snakes?
-the evolutionary age of snakes is not well known because of poor fossil records
-it is thought they have been around 100 million years (cretaceous period) but some believe they have been around for 300 million years
-oldest fossils have been found in the middle east and south America
-both marine and land dwelling
-individual snakes in the wild have relatively short lives at about 9 years
-in captivity some snakes can live up to 50 years
How do snakes move?
-they are very mobile and agile
-able to use two methods of movement at 1 time
-two common methods are simple and lateral undulation
-snakes create sideways bends in their bodies and use each bend to push off any surface that it comes in contact with
-other methods of movement include:
-Side-winding: similar to undulation but only a couple of sections are in contact with the surface and the raised parts of the body are pushed forward towards the advanced “in-contact” section
-concertina: pulls the body into bends and then straightens out again
-rectilinear: moves in a straight line by manipulating its underside scales to lift forward and then lower into the surface before moving backward using the friction of the scales pulls the body forward
Venom
-many snakes, such as vipers and cobras have evolved venom which they use to kill their prey and defend themselves in dangerous situations
-venom is modified saliva that contains a number of toxic compounds which have a range of effects including:
-paralysis
-digestion
-blood clotting
-cardiac arrest
-usually injected, some species are able to spit their venom
-there is no distinct evolutionary relationship that separates venomous and non-venomous snakes so it is believed that venom evolved more than once
Tuatara
-there are two species of tuatara (sphenodon punctatus and s. guntheri) are the only remaining species from a once diverse group of reptiles called rhynchcephalia.
-a long time ago different species from this group inhabited land, trees, and water
-now they are only found in a few forests of New Zealand
-they are most closely related to snakes and lizards
-they grow up to 60cm long
-they have a line of spikes that run down the length of their spine
-Tuatara means ‘spiny back’ in Te Reo Maori the language of the indigenous people of New Zealand
-they are cold blooded
-they are nocturnal
-they bask during the day to raise their body temp to 28 degrees C
Where are the Tuatara found?
-found only on a number of offshore islands of New Zealand
-around 800 years ago they were found on both the north and the south islands until humans introduced mammalian predators 800 years ago
Tuatara Diet
-feed primarily on invertebrates but occasionally eat lizards, frogs, and sea birds
-they have 2 sets of upper teeth and 1 set of lower teeth
-their food comes directly or indirectly from sea bird colonies
-sea birds provide food for their young which attracts insects for tuatara to feed on.
-birds that can be easily caught during the night provide an important energy source
-they are most likely nocturnal as a result of their relationship with sea birds because the invertebrates they provide can only be efficiently hunted at night
Tuatara Habitat
-live on foggy offshore islands in burrows often shared with sea birds
-they live in dense colonies with burrows separated by 2-3m
-both females and males are very territorial
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