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How many total stages are in anuran development and metamorphosis?
46 stages
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Embryonic development?
Fertilization through opercular development (Stages 1-25)
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What stages are responsible for fertilization through opercular development?
Stages 1-25
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Larval?
Independent feeding through tail resorption (Stages 26-46)
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What stages are reponsible for indepentdent feeding through tail resorption?
Stages 26-46
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Stages 10-12
Gastrulation
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During anuran development and metamorphosis, they cannot eat until what stage?
Stage 26
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Before stage 26, what do they anurans use as a food source?
Yolk
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By what stage is there muscle reponse?
Stage 18
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Stage 20
Gill circulation
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Stage 21
Cornea is transparent
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Stage 23 -25
- Operculum develops
- External gills degenerate
- Internal gills develop
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Free-swimming independently feeding larva are at what stage?
Stage 26
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Stage 23
Mouth parts begin developing, as the adhesive organ degenerates
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What happens to the labial ridges?
They become cornified
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Anurans larvae are what type of eaters?
Algae eaters
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What do anuran larvae eat?
Algae
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Stage 41
Larval mouth parts begin to degenerate as adult mouth forms
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Stage 31-38
Toe development
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Stage 39-40
Subarticular tubercles
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Stage 41
- Skin over forelimbs are transparent
- Larval mouthparts begins to degerate
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Stage 42-46
- Metamorphosis
- Forelimbs break through
- Mouthparts for insect eating
- Tail is resorbed
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How many stages do salamanders have before they hatch?
46 stages
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Some salamanders hatch with ectodermal balancers, which salamander families do they belong to?
Salamandridae and Ambystomatidae
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Some Salamandridae and Ambystomatidae hatch with _________ ___________ until forelimbs are developed.
ectodermal balancers
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Why is the metamorphsis process not as extreme for caudates?
Because they do not lose their tails and they do not have a lot of changes for their mouth parts
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Later stages of metamorphosis are promoted by high concentrations of?
Thyroxine (T3 & T4)
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What parts of the anatomy have to be working in order to get Thyroxine?
- Hypothalamus
- Anterior pituitary
- Thyroid gland
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The thyroid gland is acted upon by the TSH (thyroid stimulating horomone) from the?
anterior pituitary
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Anterior pituitary is acted upon by TSHRF (thyroid stimulating hormone releasing factor) from the?
hypothalamus
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Early development is controlled by?
Prolaction from the anterior pituitary
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Thyroxine inhibits?
Prolactin
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Neotony
Retaining larval characteristics into adulthood
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Name six salamander families that are obligate neotenes:
- Sirenidae
- Proteidae
- Amphiumidae
- Cryptobranchidae
- Ambystomatidae
- Plethodontidae
- Salamandridae
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What amphibian orders do not experience neotony?
Caecilians and anurans
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Which families of obligate neotenes do not respond or metamorphose when treated with thyroxine?
Sirenidae, Proteidae, Amphiumidae, and Cryptobranchidae
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Which families of obligate neotenes respond and metamorphose when treated with thyroxine?
Ambystomatidae, Plethodontidae, and Salamandridae
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Give an example of an obligate neotene that will metamorphose when treated with thyroxine. (Genus species)
Ambystoma mexicanum
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Facultative neotenes are influenced by?
Temperature
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Which facultative neotenes will metamorphose?
Sea level populations (Temperate regions)
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Which facultative neotenes will not metamorphose?
Montane populations
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Explain why the adult forms of facultative neotenes do not metamorphose when treated with thyroxine
Facultative neotene's tissues take longer to metamorphose because it is depends on the temperature. The age of the tissue is beyond when it can respond to thyroxine. By the time the hypothalamus is mature enough to release TSHRF, the tissues are non-responsive.
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Give an example of an facultative neotene that will not metamorphose when treated with thyroxine. (Genus species)
Ambystoma gracile
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The earliest amphibian fossils are from what geological time period?
Devonian (350 mya)
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Name the 2-fish subclasses
- Actinopterygii (ray-finned fishes)
- Sarcopterygii (lobe-finned fishes)
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Characteristics of Actinopterygii
- Ray-finned fishes
- Most of the fish we know today
- Lack internal nares
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Characteristics of Sarcopterygii
- Lobe-finned
- Gave rise to amphibians and all tetrapods
- Have internal nares
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2-orders of Sarcopterygii
- Dipnoi (lungfish)
- Crossopterygii
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2-suborders of Crossopterygii
- Coelacanthiformes
- Rhipidistia
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Characteristics of Coelacanthiformes
- Marine environment
- Most members are extinct
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Characteristics of Rhipidistia
- Fresh water environment
- All are extinct
- Gave rise to amphibians and all tetrapods
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Name the 3-subclasses of Amphibia
- Labyrinthodontia
- Lepospondyli
- Lissamphibia
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Name 3-orders of Labyrinthodontia (all are extinct)
- Ichthyostegalia
- Anthracosauria
- Temnospondyli
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Lepospondyli (all are extinct)
No orders to learn
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Name the 4-orders of Lissamphibia (1-extinct order and 3-modern orders)
- Proanuran (extinct)
- Apoda
- Anura
- Caudata
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All amphibians have what type of teeth?
Labyrinthodont teeth
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The only fish to have labyrinthodont teeth are?
Crossopterygii
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Characteristics of Ichthyostegalia (order)
- Devonian period (oldest)
- Have a fishlike skull, but pectoral girdle no longer articulates
- Nueral spines for muscle attachment
- Has a pelvic and sacrum
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Characteristics of Anthracosauria (order)
- Existed from Mississippian through Permian (about 100 million years)
- Gave rise to reptiles in mid-Permian (250mya)
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Characteristics of Temnospondyli (order)
- Existed from Mississippian through the Triassic
- Began with mostly aquatic fresh water forms
- Some became terrestrial
- Some became marine
- Possibily gave rise to modern amphibians
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Characteristics of Lepospondyli
- Extinct by early Permian
- Probably entirely aquatic
- Bizarre body shapes, but most are small and bring to mind the salamander body shape
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Characteristics of Lissamphibia
- Modern orders have adaptations:
- Pedicellate teeth
- Green rods in eyes
- Fat bodies from gonadal ridge
- Unique skin glands
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Conflicting theories
- Some believe that anurans and caecilians evolved from Temnospondyli and salamanders evolved from Lepospondyli
- Since all three modern orders have the unique characteristics, it is unlikely these all evolved independently in all three groups
- Most herpetologists believe that Lissamphibia arose from Temnospondyli
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