Question

Which of these living things does NOT have a backbone?

1) Dog
2) Human
3) Cat
4) Earthworm

Answer 1

The earthworm is an invertebrate and does not have a backbone, unlike dogs, humans, and cats which are vertebrates and do have backbones.

Step-by-step explanation:

The living thing that does NOT have a backbone is the earthworm. Animals that have backbones are known as vertebrates, and this category includes dogs, humans, and cats, which all have vertebral columns. In contrast, earthworms are invertebrates, which means they lack a vertebral column or backbone. In the animal kingdom, invertebrates make up the majority of species, exhibiting a wide range of movement types and nervous system complexities. Although they vary significantly, one commonality invertebrates share is the absence of a backbone in their structure.