Chapter 19: Amphibians

http://news.discovery.com/videos/earth-new-amphibians-emerge-in-colombia.html

Amphibians

• Include frogs, toads, salamanders, and caecilians

• Tetrapods: 4 muscular limb and feet with toes and fingers

Order Caudata

• Possess a tail throughout life• Both pairs of legs are

unspecialized• Live in moist forest-floor

litter • Have aquatic larvae• Many live in caves• Lay eggs on land• Spend most of their lives in

water and retain caudal fins• Internal fetilization

Salamanders

• Males produce a pyramidal gelatinous spermatophore that is capped with sperm and deposit it on a substrate

• Females pick up the sperm cap and store the sperm in a pouch called the spermatophore

• Eggs are fertilized as they pass through the cloaca and deposited singly, in clumps or in strings

Cave Salamander

• Found in the twilight zone of caves

• Endangered in KY• Can climb rocks

Giant Salamanders

• The largest amphibians• Can be up to 5.9 ft long• Lay eggs in strings of

200• Eat insects, frogs,

invertebrates• http://news.discovery.c

om/videos/animals-japanese-giant-salamander.html

Axolotl: endangered salamander

• Found in Mexico• Lives entire life in water

so it retains its gills into adult hood

California Tiger Salamander

• Live in Northern California

• Eats earthworms and other invertebrates

• Spends most of its life on land but returns to aquatic environments to breed

• Endangered due to loss of habitat and non-native predation

Order Gymnophiona (Apoda)

• Caecilians• Wormlike burrowers that

feed on worms and other invertebrates in soil

• Appear segmented• Retractile tentacles between

their eyes and nostrils may transport chemicals from their environment to olfactory cells in the roof of the mouth

• Skin covers their eyes

Caecilians

• Internal fertilization• Larval stages are in the

oviduct where they scrape the inner lining of the oviducts with fetal teeth to feed

• Young emerge as miniature adults

Order Anura

• 4,000 species of frogs and toads

• Live in moist environments

• Adults lack tails and caudal vertebrae fuse into a rodlike structure called the urostyle

• Hindlimbs are long and muscular and end in webbed feet

Anurans continued

• Fertilization is external• Eggs and larvae are

usually aquatic• Larval stages-tadpoles• Larvae are herbivores

Frogs vs. Toads

Frogs• Smooth slimy skin• 2 bulging eyes• Strong, long webbed feet

used for leaping and swimming

• Lay eggs in clusters• Found on every continent

except Antartica

Toads• Stubby bodies with short

hind legs used for walking• Warty and dry skin• Lay eggs in long chains• Found worldwide except in

Australia, polar regions, Madagascar and Polynesia

Frogs vs. Toads

Frogs Toads

Poison Dart Frogs

• Live in warm humid habitats

• Eat small insects• Poison cannot

permeate through a humans skin but if it gets into the body then it is deadly

Strawberry Poison Dart Frog

• Eats arthropods• Use external

fertilization• Care for one clutch at a

time (4-6 tadpoles)• Female lays eggs on a

leaf and the male makes sure they stay hydrated

Poisonous Dart Frogs

Cane Toad

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/toad_cane.html

• Possess poisonous glands and its tadpoles are poisonous if ingested

Northern Leopard Frog

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_northern_leopard.html

Misc. videos

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_strawberrypoisondart_tadpole.html

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_waterholding.html

• http://video.nationalgeographic.com/video/player/animals/bugs-animals/spiders-and-scorpions/spider_fishing_eats_frog.html

Red-eyed tree frog

• http://video.nationalgeographic.com/video/player/news/animals-news/red-eyed-tree-frogs-shaking-vin.html

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_greentree_lifecycle.html

Support and movement• Water buoys and supports

aquatic animals• Skeletons protect internal organs

and provide attachments for muscles and keep the body from collapsing during movement

• Have powerful muscles to propel themselves across land

• Skull is flattened and light so it can support itself out of water

• Vertebral column provides support and flexibility

• Zygapophyses prevent twisting

Support and movement cont

• Salamanders uses undulating movements

• Ceacilians uses accordion like movements

• Long hindlimbs of frogs and toads are modified for jumping

Locomotion

• http://video.nationalgeographic.com/video/player/news/animals-news/frog-muscle-study.html

External structure

• Skin lacks a covering of scales, feathers or hair

• Highly glandular• Secretions aid in protection• Glands keep skin moist• Produce sticky secretions

that help a male cling to a female during mating and produce toxic chemicals that discourage potential predators

External structure

• Possess glandular secretions that are toxic to varying degrees

• Chemicals are secreted when the amphibian experiences stress

• Chromatophores are specializes cells that are responsible for skin color and color changes

Nutrition and digestion

• Carnivores• Bullfrog: preys on small

mammals, birds and other anurans

• Main factors that determine diets are availability and prey size

• Salamanders: use jaws to capture prey

Nutrition and Digestion

• Use tongues to capture prey

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_bull.html

Circulation

• Separation of pulmonary and systemic circuits

• When submerged blood is highly oxygenated. BV to the lungs constrict, reduce blood flow to the lungs and conserve energy

Gas Exchange

• When submerged it takes place across the skin

• Skin is moist and has a lot of capillary beds

• Cutaneous respiration: exchange across the skin

• Buccopharyngeal respiration: exchange across moist surfaces

Gas Exchange

• Most amphibians possess lungs

• Lungs of anurans are subdivided increasing surface area

• Buccal pump: muscles of the mouth and pharynx create a positive pressure to force air into the lungs

• Increase in temp, increase in activity, increase in lung activity

• Larvae use gills

Temperature Regulation

• Ectothermic• When submerged, they

are the same temp as the water but on land they can be different temps than their environment

• Many are nocturnal

• Critical temperatures– Salamanders: -2 to 27

degrees Celsius– Anurans: 3-41 degrees

Celsius

Nervous and Sensory Functions

• Forebrain: regions that regulate color change

• Midbrain: visual sensory information and motor responses

• Hindbrain: motor coordination, regulates heart rate and respiration

Nervous and Sensory Functions

• Sensory receptors on skin

• Lateral line: responds to low frequency vibrations in the water

• Most important sense is vision

• Nicitating membranes: movable eyelids

• Tympanic membranes• Middle ear• Inner ear• Semicircular canals

Excretion and Osmoregulation

• Kidneys– Water: produce large

amounts of urea

• Freshwater: ammonia• Land: urea• Must conserve water on

land• Skin absorbs water

Reproduction, Development and Metamorphosis

• External fertilization• Amplexus: male

releases sperm as female release eggs– Can last 1-24 hours

Reproduction

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_mudpuddlemate.html

• http://video.nationalgeographic.com/video/player/animals/amphibians-animals/frogs-and-toads/frog_tadpole_development.html

Vocalization

• Used to attract mates• https://

www.youtube.com/watch?v=PY61G2hXhXI

Parental Care

• http://video.nationalgeographic.com/video/frog_strawberrypoisondart_tadpole

• https://www.youtube.com/watch?v=LFTMgaZyVSA

Metamorphosis

• https://www.youtube.com/watch?v=jR0EPHyo128