Reptiles Flashcards
Q: List the orders of living reptiles
Turtles (Testudines)
Crocodilians (Crocodilia)
Lizards and snakes (Squamata)- largest order
Tuatara (Rhynchocephalia)
Q: Where are reptiles classified taxonomically?
Reptiles are one of the five (actually >5 because multiple fish classes) classes in the Vertebrata subphylum.
Kingdom: Animalia; Phylum: Chordata; Subphylum: Vertebrata; Class: Reptilia.
Q: What differentiates reptiles from amphibians? (Hint: think about characteristics that adapted them to life on land)
Evolution of stronger, more effective jaw mechanisms.
Evolution of more effective locomotion on land.
Development of the amniotic egg, lay soft-shelled eggs on land.
Development of scales for water tight skin. Dry scaly skin.
Q: Semipermeable
(of a membrane) Allowing certain molecules, but not others, to pass through.
Q: Reptile characteristics
Ectothermic
Vertebrates
Tough, water-tight skin covered in scales (made of keratin)
Scales may be small and overlapping or large and adjoining, cannot be replaced individually (Unlike in fish), must shed skin with growth
Mainly egg laying, leathery shell, eggs must be laid on land
Q: Are there any internal processes reptiles can use in temperature regulation
Reptiles use the ability to shift blood between the body and the lungs to accelerate heating and slow cooling.
Q: First group of animals to have embryo encased in shell
Reptiles
Q: Reptile eggs
Amniotic egg
Semipermeable, leathery shell; protects from predators, pathogens, damage, drying
Semi-permeable shell allowing gas exchange while retaining essential fluids
Must be laid on land
Contains an amnion- fluid-filled sac (membrane) that cushions and protects the embryo inside.
A yolk provides the animal with food
Some reptiles give live birth
Q: Significance of evolution of amniotic egg
Reproduction no longer had to take place in water. Animals emerged from the oceans to life on the land.
Eggs could “breathe” and cope with wastes, eliminating the need for a larval stage thereby allowing the embryos to evolve into larger forms and mature further prior to hatching.
Cost: external fertilization of shelled eggs not possible, internal fertilization developed in reptiles.
Q: Which groups of animals have amniotic eggs
Reptiles, birds, and mammals all have amniotic eggs
Q: Molting
Periodic shedding of ones outer covering to make way for new growth.
Also disposes of parasites
Q: Reptile locomotion
Better adapted to locomotion on land than amphibians.
Sprawling posture with legs splayed out to the sides of the body trunk.
Twist first to one side and then to the other.
The tail provides balance and acts as a counter-weight.
Q: Reptile heart
All reptiles except crocodilians have 3-chambered heart with single ventricle.
Heart can adjust proportion of blood that goes to body versus lungs– used to accelerate heating and slow cooling.
Three-chambered heart limits ability to breath while chasing down prey. Hence ambush predators.
The fourth chamber of heart improved the crocodiles ability to actively hunt down prey.
Q: Reptile teeth, ingestion, waste
Generally simple and conical (peg-like).
Uniform in shape and size throughout jaw (homodont). Vary slightly in size.
Upper and lower tooth rows do not contact one another.
Continuously shed and replaced throughout life.
Used for killing and holding.
Swallow food whole.
Waste is uric acid, which is low in water content, reducing water loss.
Q: By what characteristic are modern reptiles split into subclasses? What is notable about the evolution of these characteristics?
-Four subclasses based on number and position of temporal fenestrae, openings in the sides of the skull behind the eyes.
-Early in reptile history, changes occurred in muscle attachment to the lower jaws and the skull in amniotes having to do w/ development of stronger and more efficient jaw muscles and a diversification in what they ate. Allowed more powerful and faster bites.
-Three patterns of holes (fenestrae) in the temporal region of the skull, just behind the eye. (details on separate card)
-Provided space for the large muscles needed for feeding when shifting from an aquatic environment to a terrestrial one where the vegetation was more coarse.
Q: Fenestrae
a small opening in the bone
Q: Three patterns of holes that developed in skulls of early amniotes.
-Different patterns of fenestrae in temporal region of skull behind eye
-0 temporal fenestrae: anapsids- turtles, tortoises and terrapins
-1 temporal fenestrae: synapsids- evolved into mammals
-2 temporal fenestrae: diapsids- birds and major reptiles (lizards and snakes, tuatara, alligators and crocodiles, dinosaurs)
Q: How are modern reptiles classified?
Temporal fenestrae, or lack thereof.
Most have two fenestrae with the exception of the turtles, tortoises, and terrapins, who lack fenestrae.
Q: Notable skull characteristics of reptiles besides teeth
Lower jaw is composed of several different bones which hinge on quadrate bone of the skull and the angular bone of the jaw.
Only one bone of the middle ear, the stapes.
The reptilian skull is attached to the spine by a single point of contact, the occipital condyle.
Q: Reptile senses
Light:
-Eyes usually large and well developed, though may be reduced in burrowing species.
-All but the snakes have eyelids.
-Lizards and snakes have light sensitive organ called the “parietal eye” on top of the head which looks like a clear scale.
Smell:
-Usually very sensitive
-Snakes and most lizards have “Jacobson’s organ” on roof of mouth. Use tongue to collect molecules in air and brush them over the organ. Tongue fork helps decipher location.
Hearing:
-Most have poor hearing and usually pick up vibrations through skull against the ground
Taste:
-not well developed
Heat:
-Some snakes such as vipers, boas, and pythons have heat sensing pits around jaws for locating endothermic prey
Q: Jacobson’s Organ
an organ of chemoreception that is part of the olfactory system of amphibians, reptiles, and mammals
Q: Parietal eye
(pineal eye)
Light sensitive (photoreceptive) organ on top of the head which looks like a clear scale
Associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation
Also acts as defensive measure, since approaching predator will cause the light to change.
Note: the parietal eye is especially visible on the common green iguana skull but not on the alligator skull on the komodo dragon biofact cart. Crocodilians lost this adaptation as have birds and mammals.
Q: Reptile reproduction; fertilization and embryo/egg development
All reptiles reproduce by internal fertilization; Males and females usually have one opening through which semen, urine, and feces can be released.
Parthenogenesis- form of asexual reproduction, growth and development of embryos occur without fertilization. Seen in several lizards and one snake species. Female Komodo dragons can produce offspring by parthenogenesis when no male is available; offspring produced are all males.
Three categories of embryo/egg strategies:
-Ovipary- external egg laying. Embryos develop outside body.
-Vivipary- live birth with a primitive placenta like structure.
-Ovovivipary- eggs maintained internally and young hatch in female and are then “born” [or hatch immediately after birth]. Embryos develop inside body, but no placental connection; embryo not nourished by food from mother.
Q: Parthenogenesis
form of asexual reproduction in which growth and development of embryos occur without fertilization
