Animal Reproduction: Methods Comparison

Animal Reproduction: Egg-laying vs. Live Birth

• Animals are categorized into classes, like fish, mammals, and reptiles.
• Animals within the same class often share similar reproductive methods (eggs or live birth).
• Most mammals reproduce via live birth, while some other classes lay eggs.

Reptile Reproduction

• Reptiles, like snakes, lizards, and skinks, typically lay eggs.
• Some scientists include birds in the reptile class due to evolutionary relationship to dinosaurs.
• Crocodiles and turtles also lay eggs.
• Some snakes and lizards give birth live, a method potentially advantageous in cold climates.

Fish Reproduction

• Most fish lay eggs.
• Exceptions include some shark species (sand and ragged tooth sharks) that give birth live.
• Guppies are another example of fish that give birth live.

Amphibian Reproduction

• Amphibians, including frogs and salamanders, nearly always lay eggs, usually in water.
• Frog eggs are often encased in protective jelly.
• Some frogs (Suriname toad) give birth to live offspring.

Mammal Reproduction

• Mammals typically have live births.
• Exceptions include the platypus and echidna, native to Australia, which lay eggs.

Fun Facts about Animal Eggs

• Bird eggshells are composed of a material similar to seashells and pearls.
• Ostrich eggs are the largest terrestrial animal eggs.
• Shark eggs are pouch-shaped (mermaid's purse).