L6 Bevan - Reptiles Flashcards
What 3 orders make up Lissamphibia?
- Urodela
- Anura
- Gymnophnia
What structure do Lissamphiban eyes contain?
Choroidal hyaline cartilage - supports the eye
How many photoreceptor types do adult amphibians typically have?
4
1 - red rods - contain rhodopsin and absorb green wavelengths
2 - green rods - unique to amphibians - absorb blue wavelengths
3 - single comes - contain pigment that has peak absorbance at yellow wavelength
4 - double cones - consists of 2 cones fused together - one contains rhodopsin, the other the yellow pigment of the single cone
What are the 2 types of pigmented cells for amphibian colouration?>
Melanophores - black, brown, red
Xanthophores - yellow, orange, red
Give an examples of a Urodela who has paedomorphosis
Axolotl
- larvae fail to metamorphose so therefore adults stay aquatic and gilled
Give 6 characteristics of Urodela
- unspecialised body form
- undulate swimming
- paedomorphosis
- 400 species
- lots live in caves
- precise courtship ritual for spermatophores transfer
What 2 characteristics turned the vertebrates into amniotes?
- Eggshell impermeable to water (but allows GE)
- Water loss reduction - combination of traits
- skin is impermeable to water
- kidneys that could excrete concentrated urine
What is the out part of an amniote egg like?
Either:
- leathery
- calcium impregnated eggshell
both of these prevent evaporation of fluids, but allow for GE
Describe the inside of an amniote egg
Stores large amounts of yolk, allows the embryo to develop to quite an advanced stage before it hatches
What are the 4 extra embryonic membranes in an amniote egg?
- Amnion - surrounds the egg itself
- Chorion - surrounds the embryo and the yolk sac
- Yolk sac - surrounds the yolk that nourishes the embryo
- Allantois - evolved o store nitrogenous waste, and aid GE between embryo and egg surface
What are the 2 main groups of Reptilia?
Synapsids - mammal like reptiles, including the ancestors of mammals
Sauropsids - lizard like reptiles
What are the 2 types of Sauropsids?
Anapsids - para reptiles, including Testudines (turtles etc.)
Diapsids:
- Archosaurs (dinosaurs, crocodiles, birds)
- Lepidosaurs (lizards and snakes)
What number of temporal fenestra (windows) do each have?
a) Turtles
b) Mammals
c) Crocodiles
a) Turtle = Anapsids - no hole
B) Mammals = Synapsids = single hole
c) Crocodiles = Diapsids = double hole
When did reptiles diversify from amniotes?
Carboniferous period (360-290mya)
Describe the physiology of reptiles
Reptiles have:
- skin covered in keratinised scales to reduce water loss
- exchange gas by the lungs
- have a heart divided into chambers that separate oxygenated and deoxygenated blood
What are the 2 parts of a Testudines shell?
- carapace
- plastron
What are the 2 groups of Testudines?
- cryptodines
- 200 species
- retract head vertically
- snapping turtles, marine turtles, tortoises, terrapins - Pleurodires
- 50 species
- retract head horizontally
- matamata
Describe the skeleton of Testudines
Vertebral column and ribs are fused to the carapace
Limb girdles inside the shell
How do Testudines breath>
Diaphragmatic ventilation - as they cannot expand their shell they pull down their diaphragm to increase the size of their thoracic cavity
How is the sex of testudine eggs determined?
Temperature:
- cool for males
- warm for females
What form of Diapsids are extinct and which still persist today?
Extinct - marine lineages of Diapsids are extinct
Terrestrial lineages that are living:
- Lepidosaurs
- lizards and snakes (Squamata)
- tuatara (sphenodontida)
What are tuataras?
The tuataras (subclass Sphenodontida) are a sister group to the lizards. This group was diverse in the Mesozoic, but only two species exist today on 30 small islands off New Zealand
What 3 groups does Squamata include?
Lizards
Snakes
Amphisbaenas
What 3 ways are snakes specialised?
Locomotion
Prey capture
Swallowing
What 3 ecological types of snake are there?
Fossorial (burrowing)
Epigean (living at soil surface)
Aquatic
What consequences physiologically did snakes face when they evolved a smaller diameter?
- left lung reduced or absent
- gall gladder posterior to liver
- right kidney anterior to left
- gonads offset (variable)
How does a snake move?
Lateral undulations
rectilinear
concertina
side winding
In what 4 ways is a snakes feeding style specialised?
- Skull has 8 flexible links - hugely flexible
- Asymmetrical kinesis
- constriction for asphyxiation
- venom
What are the 3 morphologies of venomous snakes?
- Opisthoglypous - back fanged, one or more enlarged teeth near the rear of maxilla, may have a groove to insert saliva
- Proteroglyphous - hollow fangs on from maxilla, permanently erect with shorter teeth behind
- Solenoglyphous - only teeth on maxilla are long hollow fangs, maxilla rotates to allow jaw closure
Give 5 venoms snakes have and their basic actions
proteinases (tissue destruction) hylauronidases (tissue permeability) amino acid oxidases (tissue destruction) phospholipases (cytolytic) polypeptides (neurotoxic)
How do snakes reproduce?
Internal fertilisation ubiquitous
Males have hemipenes
Oviparity - viviparity
Chorioallantoic placenta evolved in cold climates
Parthenogenesis in 6 lizard groups, and one snake group
Parental care common (brooding)
Courtship displays pheromones
Describe the subclass crocodylia
The crocodilians (subclass Crocodylia) are confined to tropical and warm temperate environments. They spend much of their time in water but build nests on land or on floating piles of vegetation.
What are the 2 groups in Dinosauria?
- Saurischia
- Sauropodomorphs (Apatosaurus, Diplodocus)
- Theropods (Tyrannosaurus, Velociraptor, Birds) - Ornithischia
- Ornithopods e.g. Hadrosaurs (duckbills)
- Pachycephalosaurs (thick heads)
- Stegosaurs (plated) and Ankylosaurs (armoured)
- Ceratopsians (horned)
