Your Complete Guide to Understanding Animals and Nature

Animal Groups and Number of Species

Here are 10 major animal groups with an approximate number of known species in each:

• Mammals – ~6,500 species
• Birds – ~11,000 species
• Reptiles – ~11,500 species
• Amphibians – ~8,000 species
• Fish – ~34,000 species
• Insects – ~1,000,000+ species
• Arachnids (spiders, scorpions, etc.) – ~100,000 species
• Mollusks (snails, clams, squids) – ~85,000 species