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42 Cards in this Set
- Front
- Back
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What are the three families and what are their shared characteristics?
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Anurans, Urodeles and Gymnophionans. Moist permeable skin, smooth and carnivorous as adults.
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What is anuans adaptations?
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Specialised for jumping, 29 families with over 4800 species.
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How are the eggs specialised?
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They have a yolk with slow clevage at the vegetal pole, with larger cells.
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How does the gut form in a frog?
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Cells at the surface of the blastla migrate and form the endomesoderm. The mesoderm grows and splits to form a coelom.
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How does neurulation (nerve growth) occur in frogs?
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Begins before endomesoderm has separated, and the neural plate thickens and rolls into a hollow tube.
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How are tadpoles specialised?
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Mostly aquatic, mostly herbivorous, and are associated with nutrients in the water increasing, which they can take advantage of.
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How do tadpoles breathe?
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young - Cutaneous respirations, and also gills.
older tadpoles - gills account for 20-40% of respiration and are internal and ventilated by a buccal pump. |
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What are the tadpole mouthparts like?
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Lacking true teeth, and are supported by 3 cartilaginous elements, 1 dorsal 2 ventral to chop and rasp food. They use the buccal pump to suspension feed and suction feed.
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Where do tadpoles live and how does this lead to adaptations?
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Still water - ovid body, tail and muscles equal.
fast flowing water - streamlined body and smaller tail fins. Semi terrestrial habitat - flat bodies, little/no tail. Direct development - large yolks and reduced mouthparts and tail fins. |
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How are midwater tadpoles adapted?
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Transparent, and may school to be difficult to attack one individual.
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How are bottom feeding tadpoles adapted?
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They scrap bacteria and algae from rocks, and may force dense agregations to create currents for suspension feeding.
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What are the stages of larval development?
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Premetamorphosis, prometamorphosis (hind legs appear) and metamorphic climax (forlimbs emerge and tail regresses)
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What happens in the final stage of metamorphosis in frogs?
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Demal glands form, mouth and head form, intestines shorten, skeleton calcifys, tail disappears, limbs grow, eyes and brain form, gills degenerate and lungs develop.
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How are frog limbs transitioned to terrestrial locomotion?
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Reduced vertebrae, long robust girdles and limbs, detached pectoral girdle and attached pelvic girdle.
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What features are in the axial skeleton of the frog?
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Inflecibility, reduced musculature due to reliace on jumping.
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What features define the appendicular skeleton of a frog?
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Pelvic girdle, strong. Hind limbs very powerful. Flexible pectoral girdle and strong forelimbs to absorb impact of landing. 4 digits to cope with this.
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How is a frog adapted for jumping?
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It has semimebranosus muscle that originates on the ischium and is insterted below the knee. It shortens fast, generates more power and has very fast intracellular processes.
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What does a walking/hopping frog say about it's lifestyle?
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Active predator, often due to their inbility to flee they have chemical defenses.
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What does a jumping from say about it's lifestyle?
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Sit and wait predators, often cryptically coloured as they can escape easily.
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What does a burrowing frog have as adaptations?
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Pointed heads, stout bodies, short legs. Spadefoot toads have a keratinised structure on hind foot for digging.
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What adaptations do climbing frogs have?
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Large heads and eyes, slim waists and long legs. Tree frogs have large toe discs, mucus glads, fluid layers on feet and frog cannot rest with it's head down or toe discs peel off surface.
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What adaptations do swimming frogs have?
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Powerful hind legs, no toungue or teeth as they use suction feeding, and retain the lateral line as adults.
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How do frogs compromise between their adaptations for breathing and for eating?
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Due to their buccal pump, a wide mouth is needed. This sucks to catch prey so they use lingual feeding, which uses a long sticky tongue to rapidly project and capture prey.
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What is cutameous respiration used for in adult frogs?
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Breathing when frog is hibernating or underwater.
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How do frogs use their buccal pump for breathing?
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4 stroke buccal force pump. 1. buccal cavity expands, 2 buccal cavity contracts (air in lungs), 3. buccal cavity expands (mouth and nare closed, lungs contract) buccal cavity contracts (air out through nares).
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How do frogs vocalise?
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using their buccal pump, to pass air over their vocal cords, resonating in a vocal sac which is a part of the buccal cavity. Males only.
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What is the problem with vocalisation in frogs?
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large energy cost. Males die due to predation. Longer and more complect calls more attractive to females and predators and more energy using.
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How is a frogs heart system?
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Double circulation. Atrium, devided, left recieves blood from lungs, right recieves blood from body. Undivided ventricle. A spiral valve in the conus arteriousus prevents oxygenated and deoxygenated blood from mixing.
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How do tadpole arteries and arches differ from adult frogs?
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3-6 arches remain in tadpoles, with 6 being pulmonary artery. 3,4 and 6 arches remain in adults, 3 supplies head, 4 supplies body and 6 supplies lungs and skin.
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What do the carotid system do in frogs?
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Supplies the head, tongue, mouth, jaw and cranium.
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How does the hepatic portal system work?
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Blood passes from the ventral abdominal vein, through the liver, drains the gall bladder, hepatic portal vein, stomach and intestines and empties into a postcaval vein.
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What is a cardiac shunt?
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Heart has a single ventricle, which allows sytemic venous blood to be shunted into systemic arteries and bypasses lungs. Used when frog is underwater, 70% of blood is shunted.
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What are the nasal organs?
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Primary olfactory organs, with 3 saclike chambres. Nares at one end, buccal cavity at other.
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What is the Jacobson's organ?
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It is an olfactory organ on the roof of mouth. Connected to brain by seperate neural pathway.
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What are the two auditory pathways in the ear of a frog?
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Tympanic membrane, airbourne sounds above 1000Hz. Opercular complex, airbourne sounds below 1000hz
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What is in the inner ear of a frog?
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2 auditory organs, papilla amphibiorum and papilla basilaris. Three semi-circular canals to maintain equilibrium.
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How do advertisement calls work in frogs?
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Produced by males, characteristic of species, bodysize and habitat. Females are responsive to male calls just before egg laying.
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How does a frogs eye work?
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Lense moves rather than changes shape, and iris dialats and contracts to control size of pupil. The eyeball has a cornea at the front and is strengthened by a ring of cartilage.
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What is unique about the photoreceptors in frogs eyes?
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Limited colour perception. They have red rods, and green rods (which are unique to amphibians).
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How does a frogs vision help it?
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With depth perception, 360 degree vision, overlapping and binocular vision for prey capture and to avoid ovstacles.
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Howw is a frogs skin adapted?
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Mucus glands - slippery skin helps escape from predators, maintains oxygen uptake. Lacks skales. And permeable so important in osmoregulation.
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How do frogs take up and maintain water?
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Live in moist areas and spend time in the ground. Frogs take up water through skin, and have a pelvic patch that absorbs water rapidly.
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