Background

Amphibians are unique in their ability to live both on the land and in water and metamorphose during their life cycle. Frogs lay eggs, usually in a string or a mass that sticks to vegetation and are fertilised by the male as they are laid. The eggs hatch into the first larval stage which lasts for 2-25 days depending on the temperature or species of frog. Life as a tadpole is spent in the water and during this life stage they have gills rather than lungs and don’t possess legs. As a tadpole, frogs grow longer and form fins, develop hind then front legs, their tail becomes shorter and their gills are replaced by lungs.

Frogs have moist skin through which they can conduct gas exchanges, as well as with their lungs and they also secrete poison through their skin, though only some species are toxic to humans. Usually the brighter colours indicate greater toxicity to humans.

Aim

The aim of this session is to:

• Investigate and understand frog anatomy and physiology

Materials

• Frog model worksheet
• Scissors, glue, coloured pencils/textas
• Access to computers and the internet
• Froguts website: www.froguts.com (follow links to the demonstration)
• Virtual frog dissection worksheets

Includes:

• Teachers notes and students activities
• Power point presentation