Amphibians Flashcards
Definition amphibians
Ectothermic vertebrates
Live in water and breath through gills in larval period
Live on land, breath through lungs and skin in adult stage
Orders of Amphibia
FROGS/ ANURA
Most habitats around the world
Only Amphibia occurs in southern Africa
include all frogs
Can vocalise
Tails in tadpole stage that are lost upon becoming adult
SALAMANDERS AND NEWTS (Molche)/ URODELA
Only northern Hemisphere
Larval and adult stages have tails
15(–150) cm
CECILIANS/ APODA (Blindwühlen, Lurche)
tropical forest worldwide
Lack tails and legs
Burrow underground
Look like snakes, but anus at the end of the body
Characteristics of Anura
no tail
respiration through lungs and skins
legs designed for jumping
external fertilisation
webbed/partially webbed feet
no toe nails
three chambers heart
smooth soft skin with glands below the epidermis—> keeps skin moist
poison glands in the dermal layer of many
Reproduction of Anura
Eggs emerge from female‘s cloak, sperm released from the male behind her fertilised eggs ( external fertilisation)
Fertilised eggs are encased in jelly-like substance:
- reduced predation
- allows debris in the water to adhere to and camouflage the eggs
- attaches the eggs to vegetation, preventing floating away
- enlarged form casing (e.g. foam nest frogs)
- glues vegetation together (e.g. leaf-folding frogs)
-protection from bacterial infections
Counter-shading of the eggs: top half dark, bottom half white
Difference between frog and toads
Characteristics Frogs Toads
Skin Smooth and moist Lumpy and dry
Teeth Some have teeth No teeth
Habitat Alongside water Often found away from water
Egg-laying In clumps In strings
Body shape Streamlined with long back legs Squat (gedrungen)
Activity Period Diurnal/nocturnal Nocturnal
Parotid gland Absent Present
Ecology /diet of frogs
Tadpoles: primary consumers
Adult frogs: secondary consumers
Intervertebrates, reptile, fledgling birds, rodents
Cannibalism is common
Large prey: bitten an swallowed
Smaller prey: flicking out a short, sticky tongue, retrieving it into the mouth, swallowed whole
Calls of frogs
ADVERTISEMENT calls
Most common
Made by males to attract females
RELEASE calls
Short grunting noise by females to terminate amplexus when finished egg-laying
Metamorphosis in frogs
tadpole
Tail and fin- folds are re-absorbed into the body
Larval mouth ( for eating algae) replaced by a mouth adapted for carnivorous lifestyle
A tongue develops
Gills are replaced by lungs
Four legs emerge
Amplexus
Grip used during mating
AXILLARY AMPLEXUS
most species
Male claps the female under the forelegs whilst fertilizing the eggs
INGUINAL AMPLEXUS
platannas and shovel-nosed frogs
Male approaches from behind, wraps his forelegs around the female‘s waist
ADHESION AMPLEXUS
only used by the fat rain frogs family
Male is considerably smaller than the female, forelegs are too small for any kind of grip.
Approaching from behind, both exude a substance through their skin that glues them together while fertilisation
Defence mechanisms
POISONS
lethal cardio-toxic poison from banded rubber frogs
aposematic colouration
Typical toads produce epinephrine from the parotid glands on the neck
FLASH COLOURATION
Angolan Reed Frog—> red skin on hidden parts of the legs, well carmouflaged
if disturbed leaping to another perch, flashing their bright red legs,….
POSTURING
toads > frogs inflate their bodies to appear larger, discouraging predators and too large to swallow
LEAPING
jumping long distances
Broad- banded grass frog
CARMOUFLAGE
Angolan Reed Frog
-30-38mm
-Very diverse in appearance: midday sun- white or white with delicate brown patches, helps reflecting sun‘s rays
Night- they turn brown with black or reddish blotches or they turn completely red
-red skin on their inner forearm and hind legs —> flash colouration
-discs on the front feed are fell developed
Habitat: Okavango Delta ; aquatic areas with reeds , bull-rushes and sedges extends up to central Africa
Call: males climb up aquatic sedges before advertising for females. The call is a single, high- peached note (like a bell)
Reproduction: deep water. Female approaches male by leaping from stem to stem, when she has selected a male the pair shuffles down the Stegmann mate at the base of the sedge, eggs are attached to submerge portion of the plant
Banded Rubber Frog
Up to 65mm
Black, rubbery skin and two bright orange/ red-to-pink stripes down the back
Skin smooth and shiny
RUBBER FROGS WALK
habitat: bushveld, savanna, grassland and costa regions from Kwa-Zulu Natal and northwards, except most parts of Namibia and Botswana, but they occur in the Delta
Reproduction: breed in permanent water and temporary pans.
Calls: Particularly after extended rains males utter a long, high pitched purrrrrrrrrr (2-3 sec)
Defence : aposemantic colouration, posture ( inflating and bending their bodies),
Exude a highly-potent cardio toxin
Guttural toad
Medium sized
Variable colours
Red Infusion on the hind leg
Dark patches on the snout
Grassland, savanna (not most of Namibia and Karoo)
During day hiding under rocks or locks
Deep guttural call
Breed in shallow water, large temporary pans and permanent still water
Eggs are laid in shallow water in paired stripes
Defence: carmouflage, posture, toxins (frothing at the mouth and skin irritation)
Giant Bullfrog Family
Tremolo Sand Frog
4,5-5 cm
Toad like frog with warty skin
Southern Foam Nest Frog
9cm, f>m
Well-defined hump midway down the back
Upper region grey, brown or white
digits have pronounced terminal discs
Skin rough but soft
Arboreal frog lives near aquatic regions of savanna and bushvelt
Nest made on branches overhanging water ( rainy season November to Fenruary)
Females secretes a liquid that is whipped into form by man and female with their hind legs.
Other males join the mating
Over 1000 eggs in one night
Foam hardens into crust
Hatching after 1 week, tadpoles fall in water
Speckled-Bellied Grass Frog
Up to 7 cm
Banding and blotching patterns on the hind leg
Spotted underparts
