Lab 7. Amphibia and Reptilia Flashcards
Amniotes
Produce amniotic eggs. Reptiles, aves, mammalia
All tetrapods belong to what class
Class sarcopterygii
3 orders of Amphibia (Lissamphibia)
- Order gymnophiona
- Order Caudata
- Order Anura
Order gymnophiona includes what
Caecilians (limbless, burrowing, almost blind)
Order caudata includes what
Salamanders and newts
Order anura/salienta includes what
frogs and toads
4 orders of reptilia
- Order testudines
- Order crocodylia
- Order Sphenodontida
- Order Squamata
Order testudines includes what
Turtles
Order crocodylia includes what
Crocodiles, alligators, caimans, gavials
Order sphenodontida includes what
tuataras (primitive, lizard-like reptiles)
Order squamata includes what
Snakes and lizards
Amphibia integument
- Thin, moist skin
- No scales except some caecilians
- Glands secrete moisture-maintaining substances
- Susceptible to desiccation
- Role in respiration
- Some = noxious/toxic compounds
- Cryptic, aposematic and mimicry colouration.
Cryptic colouration
Camouflage
Aposematic colouration
Colours indicating unpalatable prey
Mimicry colouration
Harmless prey imitates appearance of dangerous one
Reptile integument
- Thick, dry, covered in scales
- Scales formed by keratin in epidermis
- Undergo ecdysis
- Cryptic, aposematic and mimicry colouration
Turtle integument
- Shell
- Upper section = Carapace, lower = plastron
- Scutes cover both
- Skin is shed but shell stays in place. Concentric rings show growth
Frog locomotion and support
- As larvae: fusiform and laterally compressed tails for swimming
- Adults, many advances for life on land
- Skeletons substantial for support against gravity, flexible for locomotion
- Elongation of appendages, modification of vertebral column and pelvic girdles
- Fusion of many bones
- Skull is thin, light, and attached to neck
Reptile locomotion and support
- Very variable
- More ossification of skeleton for greater support
- Extra cervical vertebrae for freedom of movement of head
- Some appendages tucked in
- Bipedalism (can use front limbs for things other than movement)
- All (including birds, excluding turtles) are diapsid skulls (2 openings) turtles lack the openings.
Amphibian food acquisition and digestion (specifically anurans)
- larvae = herbivores
- all adults=carnivores mainly for invertebrates
- jaw allows them to crush prey held in mouths
- locate prey by sight and sit and wait strategy
- Specialized tongue hat folds back over floor of mouth. Flicks it out and entraps prey, flicks it back inside of mouth. Eyes sink down to force food down esophagus
Reptile food acquisition and digestion
- Eat arthropods
- All, except some turtles, are carnivores
- Turtles have heavily keratinized beak and strong neck mscles instead of teeth
- Snakes jaws and skull bones are only loosely joined so can expand lots. Also venomous fangs
Amphibian respiration
- Aquatic+larval=external gills that are reabsorbed in metamorphosis
- Adults= cutaneous. Can occur in water or on land if skin is moist
- Pulmonary resp = supplements cutaneous respiration
- Buccal pump generates positive pressure to ventilate lungs
- When weather is warm = pulmonary is most of respiration
- When temp is low, most is cutaneous.
- When hibernating in mud, gas exchange is exclusively cutaneous and blood flow to lungs is restricted
Reptile respirationi
- pull air into lungs with negative pressure
- Turtles rely on muscular contractions, the rest use movement of ribs and body wall expansion
- Can restrict blood flow to lungs when pulmonary resp not possible (like turtles in shells or diving underwater)
- Some turtles can do bimodal breathing
Circulation in tetrapods and lungfishes
- double circulation
1. pulmonary system=blood through capillary bed of lungs to collect O2
2. Systemic system=delivers blood to body
Anurans circulation
- 2 atria and 1 ventricle, but very little mixing between O2 and no O2 blood
- Cutaneous respiration and can restrict blood flowing through pulmonary circuit
Reptile circulation
- 2 divided atria, 1 partially divided ventricle (fully divided in crocodilians)
- partial opening means they can partially circumvent pulmonary circuit
Amphibian excretion
- larvae + aquatic = ammonia
- land = urea
- mesonephric kidneys = large quantities of dilute urine when in water adn conserve ions
- behaviour prevents water loss (foraging at night, returning to water during day)
ammonia
energetically inexpensive but requires lots of water to excrete
Urea
requires less water to excrete and can be stored in urinary bladder for a while
Reptile excretion
- metanephric kidney = filter large quantities of blood and produce waste with little water loss
- Uric acid (except turtles which do everything)
- Integument is impermeable so no evaporative water loss
Sensory abilities of amphibians
- Skin is sensitive
- Larvae have lateral line system
- Chemoreception (nasal epithelium, mouth, tongue and skin)
- Olfaction = important for mate recognition, detection of noxious substances and prey capture
- Sight important for prey location
- Large optic lobes
- Auditory system adapted for land (tympanic membrane, middle ear and inner ear), important for mate location
Reptile sensory abilities
- Sight and smell are important so brain regions are big
- Cerebellum is bigger due to better refined motor movement
- Ears are varied, some rely on substrate vibrations
- Sea turtles can sense earth’s magnetic field
Amphibian reproduction
- External fertilization (except salamanders and caecilians)
- oviparous and ovoviviparity (some derived viviparity)
- metamorphosis,
- differing larval and adult forms reduces competition
- some have parental care
Reptile reproduction
- amniotic egg (completed transition to land)
- oviparous
- some extensive parental care like alligators
Amniotic egg 4 parts
- Amnion
- Chorion
- Allantois
- Yolk
Amnion
Filled with fluids, surrounds embryo. Protection from desiccation and shock
Chorion
highly vascularized membrane for efficient gas exchange
Allantois
Stores waste products from embryo
Yolk
nourishes embryo throughout development
Frog skeletal adaptations for jumping
Compressed vertebral column
Urostyle (fused vertebrae at base of vertebral column)
Radioulna
Tibiofibula
Elongated proximal tarsal bones (calcanium and talus)
