Invertebrates Vs.


Classifying Animals

What are Invertebrates like?

• Nearly 95 out of every 100 animals are invertebrates.

• 8 invertebrate phyla

– Mollusks

– Sponges

– Cnidarians

– Echinoderms

– Flatworms

– Roundworms

– Segmented worms

– Arthropods


largest invertebrate phylum

• Scientist think there are more than a million arthropod species!

• Characteristics: Arthropods have….

– Jointed legs

– Body parts divided into sections

– Breath with gills or an open-tube breathing system.

– hard exoskeleton for protection

4 Main Arthropod Classes

• Arachnids

• 4 pairs of legs

• 2-section body

• up to 8 eyes

• Crustaceans

• Centipedes and millipedes

• Insects

• 3 pairs of legs

• 3 body parts: (head, thorax , abdomen)

Classifying Vertebrates

• Vertebrates can be classified into two groups using this characteristic:

Cold-blooded Warm-blooded

These animals get heat from outside their bodies. The body temperature changes with the temperature of its surroundings.

The body temperature does not change much. They use energy from food to keep a constant temperature.

**If the outside temps change, so does its body temperature.

**Cold air temperature means cold body temperature.

**If body temp changes much, this could mean sickness (like a fever for humans).


cold-blooded vertebrate dry, scaly skin lays eggs many have four legs, but some have none strong, waterproof skin breathes with lungs can live in many environments, both dry and wet



breathe through lungs, vertebrate skin, and gills during different parts of life most have 4 legs toad life cycle includes larva stage (tadpoles) salamander cold-blooded moist skin

All amphibians live near water so their skin won’t dry out.

Frogs spend half their lives in water and half on land.

Fish cold-blooded covered by scales vertebrate some species only live in freshwater (rivers, lakes) and some only live in saltwater (ocean) lays eggs in water life cycle includes larva stage breathes through gills eyes usually on side of head have fins and streamlined bodies to help them glide through water

warm-blooded have waterproof feathers vertebrate


live on land; found in all environments lay hard-shelled eggs hollow bones allow birds to fly breathe with lungs and have air sacs all birds have wings and beaks not all birds can fly


vertebrate warm-blooded most have body hair or fur breathe through lungs large, well-developed brains most live on land reproduce by live birth nurse their young with milk different kinds of teeth for eating different foods

Some Tricky Classifications to Think About

A fish? A bird? Really? A mammal? How can whales, dolphins, bats, and the famous duckbill platypus be classified as mammals?