Fact 1: Arthropods are the largest phylum of invertebrates.

Fact 2: Invertebrates have no backbone.

Given the two facts above, answer the question "What have no backbone?" with the following options: 
- insects
 - mammals
 - arthropods
 - humans
 - barnacles
 - fur seals
 - graptolites
 - bears


 

   arthropods      