Amphibians Flashcards
tetrapods
amphibians, reptiles(including birds), and mammals
amphibians are considred monophyletic
all descended from a common ancertral species, as yet not found as a fossil
anura
(salientia) tailless, hopping ambibians as adults- frogs and toads
caudata
(urodela) tailed amphibians- salamanders
gymnophiona
legless amphibians- the caecilians
amphibia
began in the devonian period, and flourished as the only terrestreial vertebrate type for millions of years
amphibian liniage
the entire clade arose form a single groupd od sarcopterygian lobe finned fish (“rhipidistian crossopterygians”)
lungs
a modification of the physostomous swim bladder acting as lungs
Chaoanae
the internal side of the nostrals that allow air to be drawn in
buccal pumping
the floor of the mouth is contracted repeatedly and quickly to force air into the lungs
layers of skin
terrestrial adult amphibians have an intigument with 5-7 layers of skin. the”old” 3 interir layers, an acellular mucus layer and the external karatinized layer
hearing
becomes associated with the middle ear bones. eye structure changes so that a “sharp” focus becomes possible in the retina
lisamphibia
(are considered monophyletic, descended from a common ancerstor)
the synapomophies:
1- lack scales, instead they have a moist integument used for gas exchnage. skin contains mucus glands that keep them moist, paratoid glnds that secrete toxins, and granular glands that secrete lost of subsinces when needed
2-papilla amphibiorum- papillae in the inner ear sensative to frequiencies below 1khz unique to amphibians
3- operculum-plectrum complex- the operculum is a bone that develops in the fenestria ovalis )oval window) in the inner ear.
the plectrum aka columella or stapes is derived from the hyiod bone of fishes
4-green rods- a special retinal cell (absent in caecilians since they have reduced eyes) that help with nocternal vision
5-levator builbi muscle- a muslce at the base of the eye that causes them to perpetually bulge outwards
gymnophiona distributions
pantropica, concentrated in south america (reflects gondwanaland(post pangea))
typhloonectidae
the only lungless family of caecelians. in everyone else only the left lung is reduced of completely absent
tentacle
chemoreceptor sensory organ. can be extended or retracted form the opening on the side of their head
fertilization
is always internal in caelilians
males have an intromittent organ called the phallodeum, formed by the eversible lining of the cloaca
there can be direct fertilization siwht ovipararity (with out without larvae stage) or viviparity. half of the speceies are oviparious
paedomorphism
Parts of the body start to develop dfferently in time tfrom other body parts (neoteny)
Neoteny
When the reporductive system is developed but the biginning of the somatic developemnt is delayed
Reproductive strategies of slamanders
- annual peters- most most slamander live where there are distinct featues, so they have a spring breeding season for example when temps rise
-biannual- some families have breddeing cucle every 2 years
Reproductive modes
External fertilization(ancestral condition with eggs laid in water and with an aquiat stage)(only sirens have external)
Interna fertilization (derived)( use spermatophores)
Spermatophore
Macroscopic structure with a gelatinos cone tiped with a sper containg cap, the male places it down and the female picks it up
Ways that salamanders are born
-aquatic egg +aquatic larva
-terrestrial eggs but aquatic larva
-terrestrial eggs +terrestrial larva that dont feed until they become terrestrial juveniles
-terrestrail eggs but theres direct developmenet form the larva inside the egg(most common)
-eggs are retained in the oviduct
Oophay
Very rare. Developing larva feed on arrrested developmednt oviducal eggs
Adelphophagy
Even rarer. Larger larva in the oviducsts eat the smaller larve
5 stages of courtship
1- male becaomes aware due to chemosensory or visial cues from the female, approches her and rubs with glands
2- imobilizes her for a bit to contrinue rubbing
3- he moves and she follows
4- male depostis spermatophore
5- females follows to find it
Types of larva
Pond type larva- large, bushy external gills(limited oxygen) and large tail(for swimming in still water)
Stream type- reduced external gills and modorate tail fin
Predator avoidance
1- skin toxicity- (from granunal glands)
2- unken reflex- arching its back to show its colorful underside
3- aposematic display- the actual bright coloring of amphibians that signal they are poisonous
4- adhesive secreation of the skin- becomes sticky i guess
Frogs v toads
“Frogs” have long limbs and leap. Have smooth skin(family ranidae
“Toads” have short limbs and hop. Have warts (large aggregations of granular glands) (family bufonidae)
types of calls
advertisement call- performed mostly by males, territorial call for other males and mating call for females
courtship call- made by males when females approach
encounter call- made by male when male aproches
release(warning)call- made by males when accidently seized by another male
reciprocation call- made by females who are able to vocalize inresponds to advertisement call
distress call- made by either sex when seized by a predator(only open mouth call)
integumantry adaptation
1- skin- skin overlying the skull may be fused to the underlying bone, helps reduce waterloss through thehead
2-mucus glands- secrete moist mucus to prevent waterloss
nuptial pads
sexually diomrphic mucus glands that develop during matuing season, are used to hold down the female(amplexus)
