_____ are the simplest of all invertebrates.
sponges
anemones
segmented worms
round worms
flat worms
sponges
Vertebrate
A)a section or part of an animal's body
B)a long appendage around the head of an animal used for holding or moving
C)an animal having a backbone
D)the individual bones in the backbone
E)not moving from place to place; attached in a permanent location