Amphibian Diversity I - Caudata

Indirect Development

Aquatic larval stage. Not as extreme as in frogs and toads.

Caudata with Indirect Development

all other caudata taxa

Direct Development

A specialized reproductive mode characterized by the omission of the free-living aquatic larval stage, with terrestrial eggs hatching directly into miniature, fully formed adults. Occurs in 300 species of plethodontids. No larval stage

Caudata with Direct Development

Plethodontidae (Lungless Salamander)

Viviparity

Female gives birth to live young, still producing eggs but they are developed internally rather than being laid

Caudata with Viviparity

salamandridae and newts

Oviparity

Female lays the eggs somewhere

Caudata with Oviparity

all other caudata taxa

External Fertilization

female lays the eggs and the male fertilizes them; cryptobranchids

Caudata with External Fertilization

Cryptobranchidae (hellbenders and giant salamanders), Hynobildae (asian salamanders), and Sirenidae

Internal Fertilization

is utilized by most species—specifically the suborder Salamandroidea—via a unique, copulatory organ-free method. Males deposit a gelatinous sperm packet called a spermatophore, which females pick up with their cloacal lips, often after complex courtship.

Caudata with Internal Fertilization

all other caudata taxa

Complete Metamorphosis

is the transformational process where aquatic, gill-breathing larvae transition into terrestrial or semi-aquatic, lung-breathing adults.

Caudata with Complete Metamorphosis

all other caudata taxa

Incomplete Metamorphosis

involves paedomorphosis, where adults retain larval traits such as external gills, gill slits, and a tail fin, remaining aquatic for life.

Caudata with Incomplete Metamorphosis

all cryptobranchids, proteids, sirenids, and some dicamptodontids, plethodontids, and ambystomid species

Two-Lined Salamander (eurycea bislineata)

As adults, they lack both lungs and gills, relying entirely on cutaneous respiration and buccopharyngeal respiration.

Northern Slimy Salamander (plethodon glutinosus)

completely lungless; relies exclusively on cutaneous respiration and buccopharyngeal respiration.

Olm (proteidae, proteus anguinus)

utilized cutaneous respiration, external gills, and with rudimentary lung systems they can perform pulmonary respiration.

Greater Siren (sirenidae, siren lacertina)

utilizes a highly specialized, trimodal respiratory system involving lungs, external gills, and cutaneous (skin) gas exchange.

Two-Toed Amphiuma (amphiumidae)

a dual respiratory system, relying heavily on long, well-vascularized lungs for breathing air at the surface, despite its fully aquatic lifestyle. While larval stages possess gills, adults lose them, retaining only one pair of gill slits (neoteny) and relying on pulmonary respiration supplemented by limited cutaneous gas exchange.

Cutaneous Respiration

Breathing through the skin.

Buccopharyngeal Respiration

Gas exchange through the moist lining of the mouth and throat.

Pulmonary Respiration

Breathing air in and out of the lungs facilitating gas exchange.

Branchial Respiration

Use of gills for oxygen exchange.

Plethodontidae Respiration

all members of this family lack lungs, relying on cutaneous respiration instead

Costal Grooves

grooves on the flanks and dorsum of some salamanders. Increase the surface area of the skin for water absorption. Provide cutaneous channels which allow water to move up the dorsum by capillary action

Sirenidae

Sirenidae, the sirens, are a family of neotenic aquatic salamanders. Family members have very small fore limbs, and lack hind limbs altogether. In one species, the skeleton in their fore limbs is made of only cartilage.

Cryptobranchidae / Hyboniidae (Hellbenders and Giant Salamanders)

Found in specific cool, clear streams in the Eastern United States (Hellbender: Cryptobranchus) and Central China and Japan (Asian Giant Salamanders: Andrias), inhabiting large rivers with rocky bottoms and hiding under boulders for shelter and breeding.

Plethodontidae (Lungless Salamanders)

Two-thirds of all salamander species. Only salamanders that have extensively radiated in the Neotropics. All plethodontids lack lungs and rely solely on cutaneous respiration. Greatest diversity of morphological specialization to particular habitats.

Salamandroidea

Ninety percent of described species are Salamandroidea. Share the synapomorphy of internal fertilization via spermatophores

Smallest Caudata

Minute Salamanders Thorius - Plethodontidae

Largest Caudata

South China Giant Salamander - Cryptobranchidae

How many species of Amphibians are there?

7,303

How many species of Caudata are there?

665

How many species of Anura are there?

6,400

How many species of Gymnophiona are there?

200

what are the two major clades of caudata?

Cryptobranchoidea and Salamandroidea

what are the two main suborders of cryptobranchoidea?

Cryptobranchidae and Hynobiidae

there are no salamanders in:

Sub-Saharan Africa, Austalasia, Tropical Asia, Most Islands

what are the seven clades of salamandroidea?

Plethodontidae, Amphiumidae, Rhyacotritonidae, Proteidae, Dicamptodontidae, Ambystomatidae, and Salamandridae

ninety percent of described species of caudata are ________

Salamandroidea

salamandroidea share the synamorphy of _________ via spermatophores

internal fertilization

largest extant salamanders have ______ metamorphosis, meaning that the adults ______

incomplete; retain larval features

____ ribs present on all vertebrae caudata between forelimb and hindlimb

short

caudata have a single vertebrae with a persistant notochord, ____ cervical vertebra, ___ - ___ trunk vertebrae, _____ sacral vertebrae, ___ - ___ caudal vertebrae

single; 11-60; single; 20-100

what are the three parts of the skull in caudata?

chondrocranium, dermatocranium, and splanchnocranium

eyes are ___ developed in most taxa

well

the opercularis consists of two components:

stapes and operculum

the opercularis has no middle ear cavity or ____ _____

tympanic membrane

____ lungs in most taxa

paired