Modern Amphibian Diversity
• 4,600 species (about the same number of mammals)
• 4,100 of these are frogs; 415 salamanders; 165 caecilians
• All continents except Antarctica
• Mostly tropical
Modern Amphibian Diversity
Gymnophiona
• Limbs absent, elongate
• Eyes covered with skin or bone
• Left lung reduced
• Tentacle present
• Male copulatory organ (phallodeum) always present
• Size range: 70 mm to 1.5 m
• 5 families:
• Caeciliidae
• Ichthyophiidae
• Rhinatrematidae
• Scolecomorphidae
• Uraeotyphlidae
Modern Amphibian Diversity
Gymnophiona
Tentacle - protrusible
olfactory organ in
front of eyes.
Develops during
metamorphosis.
Phallodeum - protrusible
male copulatory organ
(from Duellman & Trueb)
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Modern Amphibian Diversity
Gymnophiona
Modern Amphibian Diversity
Gymnophiona - Reproduction
• All caecilians have internal fertilization via the male phallodeum
• Primitive caecilians are oviparous with aquatic eggs and larvae.
• Some advanced caecilians are oviparous, but with direct
development of terrestrial eggs.
• The most advanced caecilians are viviparous and larvae have
scraping teeth (shed at birth). They scrape epithelial lining of
oviduct to obtain nutrient secreted by oviducal cells
(=matrotrophy).
Modern Amphibian Diversity
Anura
• Frogs are highly specialized amphibians - specialized for what?
• Astragulus and calcaneum are fused forming a 4th main leg
segment
• Vocal sacs well developed in males of most species
• No tail
• Tongue is large and protrusible
• Size range: 90 mm to 30 cm
• Aquatic larvae, when present, lack true teeth and have fold of skin
covering gills
• 33 families:
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Modern Amphibian Diversity
Anura
Fusion of astragulus and calcaneum
Modern Amphibian Diversity
Anura
Protrusible tongue
Prey capture
Modern Amphibian Diversity
Anura
Protrusible tongue
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Modern Amphibian Diversity
Anura
Modern Amphibian Diversity
Anura
Modern Amphibian Diversity
Anura Reproduction
• Fertilization is external except in a few species in 4 genera
• Therefore most are oviparous with aquatic eggs and larvae
• Some are oviparous, but with direct development of terrestrial eggs
• Some are viviparous (mostly lecithotrophy)
• Many species exhibit bizarre forms of parental care
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Modern Amphibian Diversity
Anura Reproduction
Family
Species
Mechanism
Parity
Nutrition
Internal Fertilization
&Via
Viviparity
A. trueii
intromittent
Oviviparous
Ascaphidae
Lecitotrophy
organ (“tail”)
Bufonidae
Nectophrynoides
Leptodactylidae
N. tornieri
Cloacal apposition
Viviparous
Lecitotrophy
N. viviparous
Cloacal apposition
Viviparous
Lecitotrophy
N. occidentalis
Cloacal apposition
Viviparous
Lecitotrophy then
matrotrophy
Mertensophryne
Via intromittent
organ (modified
cloaca)
Viviparous
?
E. coqui
Cloacal apposition
Oviviparous
Lecitotrophy
E. jasperi
Cloacal apposition
Viviparous
Lecitotrophy
Eleutherodactylus
Modern Amphibian Diversity
Anura Reproduction
Family
Species
Mechanism
Development
Discoglossidae
Alytes obstetricians
Males carry eggs on back and carries
tadpoles to aquatic habitat
indirect
Extrauterine
Viviparity
and Other Parental
Care
several
Both sexes carry tadpoles to aquatic
both
Dendrobatidae
habitat
Pipidae
Pipa
Eggs embedded in male dorsum
both
Hylidae
Fritziana
Flectonotus
Females carry eggs on back, openly or
in pouches
indirect
Hemiphractus
Gastrotheca
Cryptobatrachus
Amphignathodon
Stefania
Females carry eggs on back, openly or
in pouches. Placenta- like capillary
network sometimes develop
direct
Leptodactylidae
Cyclorhamphus
stejnegeri
Females carry tadpoles to aquatic habitat
indirect
Myobatrachidae
Rheobatrachus
Silus
R. Vitellinus
Females "eat" eggs or tadpoles and
they develop in stomach and emerge as
froglets
Both
Assa
Males carry tadpoles in paired inguinal
pouches, emerge as froglets
indirect
Modern Amphibian Diversity
Anura Reproduction
Family
Species
Mechanism
Development
Rhinodermatidae
Rhinoderma rufum
Males "eat" tadpoles and they develop in
vocal pouches and emerge as tadpoles
indirect
Rhinodermatidae
Rhinoderma rufum
Males "eat" tadpoles and they develop in
vocal pouches and emerge as tadpoles
indirect
R. darwinii
Males "eat" tadpoles and they develop in
buccal cavities and emerge as froglets
indirect
Sooglossidae
Sooglossus
sechellensis
Non-feeding tadpoles wriggle onto back
of males
indirect
Hemisotidae
Hemisus
Females attend eggs and carry tadpoles
to aquatic habitat
indirect
Hyperolidae
Hyperolius
obstetricians
Leptopelis
brevirostris
Females may brood direct developing
eggs in mouth
direct
Ranidae
Rana microdisca
Males carry tadpoles to aquatic habitats
indirect
Extrauterine Viviparity and Other Parental Care
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Modern Amphibian Diversity
Anura Reproduction
Extrauterine Viviparity and Other Parental Care
Gastric brooding frog, Rheobatrachus silus
Modern Amphibian Diversity
Anura Reproduction
Amplexus
Inguinal
Inguinal is thought to be the ancestral character state
Axillary
Modern Amphibian Diversity
Anura Reproduction
Neoteny
Why is there no neoteny in anurans?
• Some species are completely aquatic and neoteny (in salamanders,
anyway) involves the lack of a switch from aquatic to terrestrial
• There are vast differences in the ecology of adult and larval anurans:
Tadpoles are almost exclusively plant eaters, adults are not. A plant
diet requires a large gut (why?) which leaves no room for ova,
oviducts, etc.
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