Bio 123: PP18 Material Flashcards
What is the Reptile class known for?
Having an amniotic egg
What orders fall under reptiles?
-Testudines (turtles)
-Squamata (lepidosauria)
-Crocodilia
What are the sub orders of squamata?
-Serpentes (snakes)
-Lacertilia (Lizards)
What animals are Amniotes?
-Includes the reptiles, birds, mammals, and amniotes
What are the derived features of amniotes?
- They have an amniotic egg now that they are in terrestrial ecosystems which have been fully colonized by them
-They have waterproof skin
-Have costal ventilation using paired lungs (which is movement of the ribs)
What is the most ancient reptile order?
Testudines
Egg characteristics of amniotes
They retain their eggs inside without laying it out
Skin characteristics of amniotes
They now have scales, feathers, fur and waterproof skin
Costal Ventilation
It enhances their respiration by using their ribs to expand the space in the lungs to allow extra oxygen to come in. This is important b/c reptiles take on a much larger form and need more oxygen.
Parts of the Amniotic Egg
-Leathery Shell
-Chorion
-Allantois
-Yolk sac
-Embryo
What are the 4 major chambers of the amniotic egg?
- Amnion
- Allantois
- Chorion
- Yolk Sac
Purpose of the Amnion
Purple sac that directly cushions the embryo and provides protection and support
Purpose of the allantois
Where the developing embryo stores its waste
Purpose of the Chorion
Thin white layer that allows for gas exchange to occur with the external environment
Purpose of the Yolk Sac
Where the embryo receives its nutrition from
Characteristics that Reptiles have that distinguishes them from amphibians
- Better developed lungs
- Tough, dry scaly skin that offers protection against desiccation and physical injury
- Amniotic egg permits rapid development of large young in relatively dry environments
- Have an efficient and versatile circulatory system and higher blood pressure than amphibians
- Have efficient strategies for water conservation
- Nervous system is much more complex
Desiccation
Drying out
Why have turtles been so successful?
B/c of their hard shells and low metabolic needs. Turtles, crocodiles, and birds have been the only species that have survived mass environmental catastrophes.
What is the earliest known turtles?
The eunotosaurus africanus which lives 260 mya during the permian (before the age of the dinos)
What are the two extant lineages of turtles?
-Pleurodires
-Cryptodires
Pleurodires
-Known as side-necked turtles
-Live in the southern hemisphere
Neck Mechanism of Pleurodires
Can bend their neck to the side to afford their protections yet it is not as efficient b/c is still leaves their neck exposed
Cryptodires
-Hidden necked turtles
-Live in the Northern Hemisphere
-about 350 species total
Neck mechanism of cryptodires
Their cervical vertebrae allows them to bend it so that the turtles can fully pull their neck into their shell.
Evolutionary contraint of a turtles shell
There has been no selective pressure for turtles to get rid of their shell and therefore have not evolved any other traits that we commonly see such as being able to glide, slide, or live high up on trees.
Bone breakdown of a turtle
-Neck
-Ribs
-Fused Vertebrae
-Carapace
-Plastron
Carapace
The top of a turtles’s shell
Plastron
The bottom of a turtles shell
What are the classifications of amniotes based on temporal fenestration?
- Anapsid (turtles)
-Synapsid (mammals)
-Diapsid (other reptiles/birds)
Temporal Fenestration
Posterior to the orbit
Anapsid
Has no opening posterior to its orbit
Synapsid
Has 1 opening posterior to its orbit
Diapsid
Has 2 openings posterior to its orbit
Gender of turtles
-Turtles do no have sex chromosomes
-They have temperature sex determination where gender is determined by the temperature they were in during incubation
Temperature sex determination
Cooler temps. leads to males and hotter temps. lead to females
Conservation concerns in regards to a turtles eggs
Global warming can cause a giant skew towards one gender because as the ground warms up, then it will affect temperature sex determination (for turtles we would se more and more females being born over males)
What other animals have temperature sex determination?
Crocs
What falls under the Order Squamata?
(Lepidosauria) - Common name is Lizards and snakes
What is the first sub-order of Squamata?
The Serpentes (aka the snakes)
What are the two types of venomous snakes?
Elapids and Vipers
What group of snakes if nonvenomous?
The Colubrid
What falls under the Elapids group?
The cobras and coral snakes
What falls under the Colubrid group?
The garter snakes
When is a statistical characteristics of snakes?
Out of 3,900 species, only about 600 (15%) of them are actually venomous.
What type of toxins do elapids and vipers produce?
Elapids produce neurotoxins while vipers produce hemotoxins.
Neurotoxin
Venom that are destructive to nerve tissue
Hemotoxin
Venom that specifically targets red blood cells which affects tissues and internal organs.
Where do venomous snakes store their venom?
Them have a swollen posterior where venom glands are stored. A typical sign of a snake being venomous is if they have a swollen head (bicycle seat looking head)
Characteristics of BOAS?
They are non venomous but kill their prey by constricting them to death.
What is the Pit organ?
It is also called the loreal pit; it allows for the detection of infrared radiation (heat) that is given off by other organisms.
Characteristics of snake bites
Snakes have an immensely fast strike and they have fangs as sharp as hypodermic needles. Adult snakes can also have a dry bite where no venom is released from their fangs when they bite.
Olfaction advances in snakes
-They have a vomeronasal organ (also called Jacobson’s organ)
-They extend and flap out their tongues which captures odor particles from its environment and are mixed with fluids in the mouth which are then delivered to the ducts that lead to the vomeronasal organ.
-The mouth is connected to Jacobson’s organ.
-This process increased their ability to smell.
Characteristics of a snake feeding
-Snakes have highly kinetic skulls which allows them to eat organisms that are much bigger than they are.
Quadrate Bone
Not rigidly attached and connects the maxilla and dentary which allows the jaw to be more flexible. The quadrate bone pivots vertically and horizontally which allows the jaw to rotate.
Lower jaws of snakes
The lower jaws of snakes are not fully connected. It is actually two pieces that are connected by an elastic ligament which allows each side of the jaw to move independently from one another.
What is the second sub order of Squamata?
Lacertilia (aka the lizards)
Characteristics of Lizards
-Includes approximately 7,000 species
-Drastically range in sizes from 16mm geckos to 3m komodo dragons
What is the scientific name for geckos?
Sphaerodactylus
What was the Megalania prisca?
A fossil from the Pleistocene era that was found in australia and was 5.5 m long which would be the largest lizard alive.
Varanidae
The largest family of lizards that includes the komodo dragons and the monifers
What is the ice age era called?
The Pleistocene era
Tail Autonomy of Lizzards
Some lizards can drop their tail as a defense mechanism but can only do it once in their life span. Their tail is replaced by a cartilaginous rod.
What is the trade off to lizards dropping their tail?
They have to be very selective of when and if they drop their tail because females will favor males that have not dropped their tail. This is because having dropped your tail signifies to the females that the male came really close to death and might not be a good mate for protection.
What is another defense mechanism of lizards?
They are able to camouflage into their surroundings to hide from predators.
Diversity of Lizards
There are all sorts of different forms that lizards can take such as iguanas, chameleons, and those that have horns in their exterior for protection.
Reversals in Lizards
There is a worm like lizard called the Amphisbaenia. Which is a legless lizard that is fossorial, and the shape of its head allows them to be efficient diggers.
What is the third order of the class reptiles?
Crocodilia
Survivorship of crocodilia
They survived the dino extinction and are the most closely related relative to birds.
Characteristics of Crocodilia
- Includes 28 species of crocs that is divided into 3 families
- Most are semiaquatic
- Although they are big and bulky, they can move relatively fast in land (some can gallop)
- They have a laterally compressed tail, and have a dorsal-ventrally flattened body/head
-They also have a jaw strength that can easily snap human bones
What are the 3 families of crocodilia?
- Alligatoridae
- Crocodylidae
- Gavialidae
Characteristics of Alligatoridae
Includes the alligators and caimans. Predominantly new world and live in freshwater. Are also less aggressive and are more likely to run away from danger or if spooked.
Characteristics of Crocodylidae
- True crocs
- Cosmopolitan (all over)
-Mainly live in saltwater
-Freshwater species are euryhaline
Estruaries
Where salt water and freshwater meet
Nilecrocodile
The most aggressive species of crocodiles
Gavialidae
-Have a very narrow snout
-Piscivorous
Piscivorous
Feed on fish
Body structure differences in crocodilia
- Alligators have a broad snout while crocs have a snout that comes to a point.
- A gharial has a very thin and pointy snout.
- In alligators, the first teeth we see stick out are from the upper jaw.
- In crocs, the first teeth we see stick out are from the bottom jaw.
Parental Care of Aligators
Alligators take on active parenting roles by doing things such as bringing food to their young.
Sex determination of crocs
Crocs are temperature sex dependent and do not have sex chromosomes.
Feeding habits of crocodilia
-Are sit and wait attackers and will surprise attack its prey by jumping out of the water
-Have huge powerful jaw muscles that can easily disable its prey
-Typically drag prey into water to quickly drown its prey
-Will tear (dismember) its prey apart
-Will utilize the death roll (which is axial rotation) to easily subdue its prey
