What Animals Are Included In The Class Reptilia

Effigy 1: Comparing Reptiles and Amphibians

Review padlets (pass: bio)

Biology 2-1 review question padlet

Biology 1-1 review question padlet

Reptiles were the outset animals adjusted to life entirely on land .
Reptiles evolved from amphibians ~ 320 million years ago and displaced amphibians in many environments.
Reptiles are ectotherms ("cold-blooded")

Major Evolutionary Advancement – Amniotic Egg

Developed from internal fertilization and provides the embryo with atmospheric oxygen, nutrient, and water.
Egg covered in a mineralized shell – reptiles take leathery eggs
Removes nitrogenous wastes and protects the embryo from drying out.
This marks the kickoff of the amniotes ( animals with amniotic eggs)
Amniotes include : Class Reptilia, Form Aves, and Class Mammalia.

The amniotic egg is dissimilar because they have four extra membranes:

a. Amnion – thin membrane enclosing the fluid in which the embryo floats/prevents drying out.

b. Allantois – stores wastes produced by the embryo.

c. Yolk Sac – Surrounds the yolk (nutrients for embryo)

d. Chorion – Outermost membrane of the egg – protects embryo and allows gas substitution

Figure ii: Diagram of a reptilian Amniotic Egg

General Anatomy

Have claws to protect and help them obtain food
ninety degree leg position Provides greater body back up compared to amphibians.

Integument: Tough, dry scaly skin that offers protection against desiccation (drying out) and physical injury.

Pare can also have chromatophores for colouration.
All reptiles shed their skin, still snakes shed the entirety of their skin in one session. This replaces old worn out skin and removes parasites.

Effigy iii: Komodo Dragon (taken by me!)

Physiology

Ectothermy – "Cold blooded"
Reptiles are ectotherms, meaning they rely on environmental (or outside) heat sources
Since they do non produce much internal sources of oestrus/regulation, ectotherms are able to use much less energy and have lower metabolic.
The term "cold-blooded" is technically non correct since claret temperature changes with environmental temp.

Figure 4: Graph of ambient temperature vs. body temperature. Observe how the ectotherms temperature is rises with the ambient temperature, where equally endotherms (who produce their own heat) maintain a relatively steady temperature.

Merely, What most fish and amphibians?
Fish and amphibians are all ectothermic likewise!
Question: Reptiles and all previous vertebrate classes are ectothermic – tin can you make a prediction equally what major evolutionary advancement will occur in terms of thermoregulation?

Physiology – Senses

Jacobson'due south Organ

The olfactory areas in the nose are not well developed in reptiles.
Using their tongues, many reptiles, amphibians, and mammals can can notice chemicals (odour/gustation) in the air via the Jacobson's organ.

Heat -sensitive organs (or pits)

In some snakes
Detect the heat from casualty, and nerves transmit this info to the same area in the brain that receives optic nerve impulses (sees a "heat image" of prey – just like an infrared camera!)

Physiology – Digestive System

Digestive tract is similar to amphibians, however is longer, with a larger J shaped s

Effigy six: Comparing vertebrate digestive systems (commencement five classes)

tomach (similar to higher vertebrates such every bit mammals)
It includes the rima oris and its salivary glands, the esophagus, the stomach, and the intestine and ends in a cloaca .
One pair of salivary glands evolved to go venom glands in many reptiles. (yes, snake venom is modified saliva!)

Fun fact : Evolution of Snake Venom

In snakes, venom has evolved to kill or subdue prey and due to its effectiveness, snakes diversified relatively apace.
Interestingly, the venom organization has also subsequently atrophied, or has been completely lost in many species after its evolution.
For example, many American Rat Snakes lost their venom following the evolution of constriction as a means of prey capture. (notwithstanding they still possess remnants of the organisation)
BC has its own venomous rattlesnake – The Northern Pacific Rattlesnake (Crotalus oreganus oreganus)

Figure 7: Northern Pacific Rattlesnake range

Physiology – Reproduction

Oviparous with internal fertilization (lays amniotic eggs)
Most male reptiles have two sexual activity organs called hemipenes . They are housed internally in males only at the base of the tail, and are everted when needed.

Effigy viii: Everted hemipenes (Order Squamata)

In many snakes, the hemipenes possesses spines or hooks, in order to ballast the male within the female.
Unlike many other reptiles, alligators/crocodiles use a penis that is ever erect and "pops" out of their bodies to mate

Effigy 9: A graph plotting proportion of female turtles built-in vs. incubation temperature
In some reptiles, nest temperature determines sex of the hatchlings. This is called temperature-dependent sexual activity determination.For instance, In turtles, low temperatures during incubation produce males and high temperatures produce females.

Parthenogenesis – reproduction

Parthenogenesis = reproduction from an ovum without fertilization
The only vertebrates that show true parthenogenesis are the squamates, with most l cadger species and one ophidian beingness obligate parthenotes.
These are unisexual species, all individuals being females that reproduce asexually without the intervention of whatsoever male person.
Ex. Tropical Nighttime Lizards

Physiology – Circulatory system

Figure 10: Comparing vertebrate hearts

Nigh reptiles accept a iii -chambered heart and double loop claret circulation (similar to amphibians)
Withal, reptiles have an incomplete septum, or wall dividing the ventricle into two.
More efficient than amphibians, but still not the most complex!

Effigy eleven: Typical reptilian circulation (Guild Crocodilia not included)

Figure 11-b: Comparing Vertebrate respiratory systems

Crocodiles – a big difference!

Society Crocodilia (Alligators and crocodiles) have developed four chambered hearts and are closely related to birds – What heart structure would you await in Class Aves?

Physiology – Respiration

Reptiles are more than active than amphibians, and so they need more oxygen.
Reptiles cannot skin breathe; their dry scaly skin is "watertight" to avoid h2o loss.
The lungs of reptiles contain a larger surface expanse

Figure 12: Comparing amphibian and reptile lungs

Groups of Reptiles

Order Testudines ("Turtles, tortoises, terrapins")

In North America:

Turtles…

Are usually water -dwelling and have streamlined, disk -shaped shells and webbed feet or flippers to apace motion in h2o.
They swim, but they also climb out onto banks, logs, or rocks to bask in the sun.

Tortoises…

Are state -dwelling and tend to have dome -shaped shell to retract their head & limbs.
They have thick sturdy legs and anxiety for moving on land and eats low-growing shrubs, grasses, and fifty-fifty cactus.
Tortoises that live in hot, dry habitats use their potent forelimbs to dig burrows .

Terrapins…

Spend their time both on land and in water, and alive along rivers, ponds, and lakes. Terrapins are ofttimes found in brackish , swampy areas.

Lodge Squamata ("Lizards and Snakes")

Snakes and lizards have a kinetic skull , which means it is modified to take movable joints, specialized for eating large prey.
In snakes, the two halves of the lower jaw (mandibles) are joined merely by muscles and skin, assuasive them to spread widely apart.
Since a snake must go along animate during the deadening process of swallowing, its tracheal opening (glottis) is thrust forward between the two mandibles.
Swallowing may accept several hours but saliva begins digestion during swallowing.

Snakes take no external ears or tympanic membrane, simply are quite sensitive to vibrations carried in the ground – their jaw carries the vibrations into the ear to the cochlear os

Order Crocodilia ("Crocodiles and alligators"

Crocodilians are large, aquatic reptiles; of the living reptiles, they are the most closely related to dinosaurs .
Alive in tropical and subtropical regions around world and tin ordinarily exist distinguished based on head morphology:

Crocodiles – Long triangle -shaped heads; when oral fissure is airtight you tin meet the upper and lower teeth showing; teeth vary in size.

Alligators – Wide apartment heads with round noses; When oral fissure is closed only the upper teeth are showing; Teeth vary in size.

Figure 17: Crocodile and alligator morphology

All are aggressive carnivores

Guild Sphenodontia ("Tuataras")

Tuataras are nocturnal, lizard-similar reptiles that live in burrows oftentimes shared with petrels. They usually hide in burrows during the day and feed on insects, worms, and other pocket-size animals at nighttime
Only ii living species; both inhabit but a few pocket-size islands of New Zealand.
They were once widespread throughout the ii main islands of New Zealand. Humans introduced not-native animals, including rats, cats, dogs, and goats, which prey upon tuataras and their eggs.

Figure 18: Tuatara