Backbone Detectives Activity Packet
Indiana 3.LS.1 & 3-LS4-1 Grade 3 Life Science
Backbone Detectives: Vertebrates vs. Invertebrates
Name:
Date:
Detective Mission: Earth is home to millions of animal species! Biologists sort all animals into two main groups based on one key structural clue: whether they have a backbone inside their body.
1. Vertebrates Has Backbone
Vertebrates are animals that have a spinal column (backbone) and an endoskeleton (an internal skeleton made of bone or cartilage).
- Skeleton grows along with the animal's body
- Protects internal organs (brain, heart, lungs)
- Includes: Mammals, Birds, Reptiles, Amphibians, Fish
Key Feature: Internal bony spine & skull
2. Invertebrates No Backbone
Invertebrates are animals that do not have a backbone. Over 95% of all animal species on Earth belong to this huge category!
- Some have a hard outer shell called an exoskeleton
- Others have soft, fluid-filled bodies (hydrostatic support)
- Includes: Insects, Spiders, Snails, Worms, Jellies
Key Feature: No internal bone column
Dossier Debrief: Read & Respond
1. What primary body part determines whether an animal is classified as a vertebrate?
2. Explain the difference between an endoskeleton and an exoskeleton in your own words:
3. True or False: Earthworms are vertebrates because they can bend easily. Explain your answer:
Field Guide Dossier • 3rd Grade Science Page 1 of 4
Animal Kingdom Branching Map
Structural Organizer
Complete the classification branch map below. Fill in the missing classification labels and write one Indiana animal example for each group on the lines provided.
ANIMAL KINGDOM
GROUP A: VERTEBRATES (Has Backbone)
5 Major Classes of Vertebrates:
1. Mammals (Fur/Hair, Milk) Ex: ________________
2. Birds (Feathers, Beaks) Ex: ________________
3. Reptiles (Scales, Dry Skin) Ex: ________________
4. Amphibians (Moist Skin) Ex: ________________
5. Fish (Gills, Fins, Scales) Ex: ________________
GROUP B: INVERTEBRATES (No Backbone)
Major Invertebrate Types:
1. Insects (6 legs, 3 parts) Ex: ________________
2. Arachnids (8 legs, 2 parts) Ex: ________________
3. Mollusks (Soft body / Shell) Ex: ________________
4. Crustaceans (Hard armor) Ex: ________________
5. Annelids (Segmented worms) Ex: ________________
Skeletal Structure Comparison Matrix
| Animal Specimen | Classification (V or I) | Support Structure Type | How It Protects Body |
|---|
| White-Tailed Deer | _________________ | _________________ | ________________________ |
| Monarch Butterfly | _________________ | _________________ | ________________________ |
| Eastern Box Turtle | _________________ | _________________ | ________________________ |
| Nightcrawler Worm | _________________ | _________________ | ________________________ |
Animal Kingdom Branching Map • 3rd Grade Science Page 2 of 4
Differentiated Specimen Sorting Lab
Level 1 & Level 2 Tasks
Field Specimen Bank (10 Organisms)
Bald Eagle Honeybee Bullfrog Garden Snail Largemouth Bass Wolf Spider Red Fox Earthworm Crayfish Garter Snake
TIER 1
Primary Sort: Backbone vs. No Backbone
VERTEBRATES (Has Backbone)
INVERTEBRATES (No Backbone)
TIER 2
Advanced Structural Analysis: 3 Body Support Types
A. Endoskeleton
Bones/cartilage inside body
B. Exoskeleton
Hard armor shell outside
C. Soft/Hydrostatic
Fluid pressure / no hard bones
Detective Mystery Case: The Box Turtle Riddle
"A box turtle has a hard outer shell just like a beetle. Does this mean a turtle is an invertebrate?" State your scientific explanation below:
Differentiated Specimen Sorting Lab • 3rd Grade Science Page 3 of 4
Scientific Analysis & Creature Architect
Indiana CER Lab
INVESTIGATION SCENARIO Creek Discovery Debrief
During a field trip to an Indiana state park, Leo finds a crayfish in a stream. Leo claims: "This animal has hard armor, walking legs, and snaps its claws, so it must be a vertebrate animal!"
Claim (Is Leo correct? What is a crayfish's true classification?):
Evidence (What structural traits from the text support your claim?):
Scientific Reasoning (Explain WHY this evidence connects to backbones/skeletons):
Creature Architect: Design a Specimen
Engineering & Science Integration
Draw your specimen & label its skeletal support:
1. Creature Name:
2. Classification:
Vertebrate Invertebrate
3. Support System:
Endoskeleton Exoskeleton
4. Survival Feature (How skeleton helps it move/protect):
CER & Creature Architect Lab • 3rd Grade Science Page 4 of 4
